Sustainable and environmentally friendly composites: Development of walnut shell powder-reinforced polypropylene composites for potential automotive applications
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Mohammed A. Al-Sarraf
Abstract
In order to lessen carbon emissions, preserve natural resources, and enhance the planet’s sustainability for future generations, environmentally friendly and sustainable composites offer a promising solution that combines technological innovation and environmental responsibility. Therefore, the current study focused on the development of walnut shell (WS) powder as a natural reinforcing additive for polypropylene (PP) composites as sustainable materials for potential automotive applications. Different particle sizes (150, 212, and 300) μm and particle content (10, 20, 30, and 40 wt%) of WS-reinforced PP composites were investigated. This investigation involved two strategies: The first strategy was to determine the best WS size and loading in the PP matrix. The second strategy involved the development of additives by applying dual treatment methods on the WS: alkaline and microwave as chemical and physical treatment at the same time. Under fixation microwave conditions, different NaOH concentrations of 3, 5, and 7% were applied. The extrusion and hot compression processes at fixed operating conditions were used to combine all dosages of WS/PP composites. The mechanical properties of tensile, flexural, and impact for all the composite dosages for the strategies were studied according to ASTM standards D638, D790, and D256, respectively. To confirm the mechanical properties, the influence of treatment techniques on the WS powder and WS/PP composites was also investigated using physicochemical characterization Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray diffraction. Furthermore, the best WS/PP composite was compared with the real automotive part (automobile steering airbag cover [ASAC]) to confirm the mechanical properties of the new WS/PP composites. The results showed that the first strategy obtained a 212 μm, 20 wt% composites that achieved the highest tensile strength, which increased about 1.2 times the tensile strength of the PP matrix. The second strategy showed composite that had treated WS with 7% NaOH (WS7Comp) attained the best mechanical properties throughout other WS/PP composites. In addition, the mechanical properties of the new WS/PP composites were adjusted to the ASAC mechanical properties. Therefore, the improved composites could be a promising alternative material for automotive applications.
1 Introduction
Finding environmentally friendly and recyclable materials is one of the key challenges for industry, especially the automotive industry [1,2,3,4,5]. The use of sustainable composite materials made from polymers reinforced with natural fibers represents a promising solution that helps reduce environmental impact and achieve sustainability [6,7,8,9,10]. Natural fibers have unique properties such as lightness, durability, and the ability to biodegrade, making them an ideal choice for reinforcing thermoplastic polymers with the aim of producing composites with improved mechanical properties and wide applications in the automotive and other industries [11,12,13,14]. The number of vehicles worldwide has grown significantly over the past five decades, increasing from about 29.4 million units per year in 1970 to about 94 million units in 2023 to meet significant population growth worldwide [15,16,17,18,19,20]. This growth shows the importance of researching and developing sustainable materials in the automotive industry to reduce environmental impact and improve economic sustainability [21,22,23].
Natural fibers such as flax [24], jute [25], bamboo, date palm fiber [26,27,28,29,30], sugar palm fiber [31], oil palm fiber [32,33,34,35], and walnut shells (WS) [36] are renewable and environmentally friendly resources, lightweight and durable. These properties make them an ideal choice for reinforcing polymers, producing composites with improved mechanical properties and wide applications in the automotive industry [37,38,39,40]. Natural fiber-reinforced composites offer a sustainable solution that helps reduce environmental impact by reducing reliance on non-renewable sources and reducing plastic waste [41,42,43,44,45].
Despite the many advantages of natural fibers, their use faces major challenges, the most important of which is their hydrophilicity. Natural fibers strongly absorb water, resulting in poor mechanical structural design of composite materials [46,47,48]. This property leads to a reduction in toughness and an increase in ductility, which reduces the efficiency of composites when exposed to moisture [49,50,51].
Many previous studies have adopted the processing of natural fibers to improve their physical and mechanical surface properties in combination with polymer materials. For example, Abdella et al. treated bamboo fibers with alkali and stearic acid, with results showing improvement in the mechanical properties of bamboo fiber-reinforced high-density polyethylene composites. In addition to the improvement in the surface of the natural fibers, which was reflected in the unique bond between the fibers and the matrix, scanning electron micrographs also showed this change [52]. El-Shekeill et al. showed that the effect of microwave treatment on the tensile properties of composites made from sugar palm fiber-reinforced thermoplastic polyurethane composites improved by 39% due to NaOH and specific thermal with the electromagnetic effect of the chemical and physical methods that good interaction between the fibers and created the matrix [53]. Espinach et al. investigated the influence of different chemical treatments on the thermal and mechanical properties of polypropylene (PP) composites reinforced with jute fibers. These composite materials were prepared for use as interior parts of automobiles. The result showed that the treatment improved the physical and chemical properties of jute fiber, which improved the mechanical properties of the prepared composites [54]. Abed, Chen, Mylsamy, Widodo, Cai, Gani et al. investigated the effect of processing the PLA matrix reinforced with kenaf fibers using different concentrations of sodium acetate. The verification results showed a noticeable improvement in the mechanical properties of green materials to replace industrial materials with sustainable, environmentally friendly materials [55,56,57,58,59,60].
WS are one of the agricultural cellulose wastes and are therefore considered a natural source of sustainability due to their low cost, availability, lightweight, high biocompatibility, and non-toxicity [61,62,63,64]. Walnuts are mainly grown in the northern regions of Iraq, such as the Kurdistan Region, particularly in the governorates of Dohuk and Sulaymaniyah. These areas are characterized by a temperate climate and fertile soil, making them ideal for cultivation [65,66,67,68,69,70].
Walnuts are rich in many beneficial nutrients, the most important of which are omega-3 fatty acids, protein, fiber, vitamin E, and vitamin B6, and they also contain minerals such as magnesium, phosphorus, copper, and manganese [71]. Iraq’s annual walnut production is estimated at 10,000 tons. The ratio of the weight of the walnut to the shell is approximately ±40–50% of the total weight of the fruit. Therefore, the peels make up about ±50–60% of the total weight of the fruit. In other words, Iraq has more than ±7,000 tons of peels of this fruit annually [24]. The accumulation of these crusts poses a burden on the environment. Therefore, the need arose to use this natural material as a sustainable natural material. WS powder has good mechanical properties and is therefore suitable for reinforcing polymer composites as a traditional synthetic alternative. It is a renewable and environmentally friendly material that increases the strength of polymers with the advantages of low cost and recyclability [72]. Adding WS powder to PP improves the cohesion within the matrix through chemical reactions between the hydroxyl groups in WS and the PP, improving tensile strength and reducing deformation under load. The improved cohesion helps to distribute stress and reduce cracks effectively. WS also contribute to lower density and improve the strength-to-weight ratio without significantly compromising durability [26]. However, there are several challenges encountered in the processing and manufacturing of WS powder-reinforced PP composites, such as inhomogeneous distribution, moisture absorption, and poor adhesion between fiber and matrix [73]. Therefore, the potential applications of this type of composite materials are in the interior and exterior parts of automobiles.
PP is a common plastic polymer characterized by its rigidity, flexibility, chemical and moisture resistance, and thermal stability. It is widely used in packaging, household goods, medical, and automotive industries [74]. Its low cost and abundant production make it an economical material and make it an attractive choice for many industrial and consumer applications. Because of these properties, PP remains an indispensable polymer in many applications [28,75].
Therefore, the current study focused on the development of WS powder as a natural reinforcing additive for PP composites as sustainable materials and then investigated the effect of different particle sizes, particle content, and treatment methods on the mechanical properties of the WS/PP composites. Different particle sizes (150, 212, and 300) μm and loadings (10, 20, 30, and 40 wt%) of WS-reinforced PP composites were examined to determine the best WS size and loading in the PP matrix. A dual treatment method at the WS, alkaline and microwave as chemical and physical treatment, was applied simultaneously to improve the new WS/PP composites. The effect of different NaOH concentrations of 3, 5, and 7% on the mechanical properties of WS/PP composites was investigated under specified operating conditions. Eventually, to confirm the final result of the WS/PP composites, the chemical characteristics of the untreated and treated WS and their composites were investigated by employing Fourier transform infrared spectroscopy. Lastly, the mechanical properties of the new WS/PP composites were compared with the mechanical properties of the ASAC.
2 Materials and Methods
2.1 Materials
Iraqi walnuts were purchased at local food markets, then the pulp was removed, before washing them with tap water to remove dust and suspended impurities to prepare them for the milling process. The density of WS is 1.33 g/cm3; in addition, it contains cellulose (23.55%), hemicellulose (29.28%), and lignin (37.14%) [29]. Homo-polypropylene (Homo-PP) was purchased from Polypropylene Malaysia SDN BHD with properties: density 0.905 g/cm³, melting point 160–165°C, tensile strength 30–40 MPa, flexural modulus 1.5–2.0 GPa, and impact strength 2–5 kJ/m² (notched Izod impact strength) [30]. Reagent-grade sodium hydroxide (NaOH) pellets were purchased from Thermo Fisher Scientific India Pvt. Ltd, Delhi, India, with the properties listed in Table 1.
NaOH properties
| Features | Description or values |
|---|---|
| Appearance | White |
| Melting point | Range 318°C/604.4°F |
| Boiling point/range | 1,390°C/2,534°F |
| pH | 14 |
| Viscosity | (5%) |
| Bulk density | 2.13 g/cm3 |
2.2 WS powder preparation
At the beginning of preparing WS powder, the WS were washed three times with tap water to remove dust and impurities. Furthermore, WS was left in a laboratory oven model: 202-80 AB table thermostat dryer, China (Figure 1), with operating conditions; temperature 80°C, and time 6 h before grinding. The grinding process was carried out for three runs using a laboratory grinder machine type SILVER CREST, China (Figure 2), for 5 min each run to collect an adequate weight before beginning the sieving process. The powder of WS was dried again in the oven at a temperature of 80°C for 8 h. The screen mesh symbols for different sizes correspond to the number of holes per linear inch. Typically, the American Society for Testing and Materials standard “E11ASTM” is used for this purpose [31]. Therefore, a mesh size of 100, 70, and 50 was used to obtain three different sizes: 150, 212, and 300 μm of WS powder. For this purpose, the Fritsch Analysette 3 Spartan vibratory screening machine was used to separate these different sizes of WS powder (Figure 3). The sieving processes were applied six times to collect sufficient WS powder for the production of WS/PP composites. The weights of the materials were balanced using a sensitive scale, model “ANDRU Digital Laboratory Analytical Weighing Scale, Electronic” (Figure 4). Finally, the WS powder was stored in plastic bags together with silica gel to prevent moisture influence on the powder.
Laboratory oven model; 202-80 AB Table Thermostat Dryer, China.
Laboratory grinder machine type Silver Crest.
Fritsch Analysette 3 Spartan vibratory screening machine.
Balance sensitive scale, model Andru Digital Laboratory Analytical Weighing Scale, Electronic.
2.3 Treatment of WS powder
WS powder underwent chemical and physical treatment by using alkali and microwave methods at the same time. The microwave model Samsung Solo Mikrowelle 23-l was used for the treatment. Different concentrations of 3, 5, and 7% NaOH were applied to the WS powder to study their effect on the mechanical properties of WS/PP composites. These reactions were carried out by adding the NaOH pellets and distilled water to the microwave flask. The microwave system was equipped with a stirrer model “KA Work Janke & Kunkel Blender/Mixer Type RW 18 Overhead Stirrer” for mixing the WS powder with the NaOH solution and a condenser to maintain the concentration of the NaOH solution during the reaction. Table 2 illustrates the fixing microwave conditions. The time and temperature were 20 min and 80°C, and the stirrer rotation speed and microwave frequency were also set at 80 rpm and 2.2 GHz. After each treatment, the WS powder was washed four times to remove reaction residues and prevent decomposition (Figure 5).
Illustrate the three experimental steps with most preparation conditions for WS/PP composites
| St. | WS/PP comp. | NaOH (%) | Microwave conditions | WS size (µm) | WS content (%) | Extrusion conditions | Compression molding conditions | |||
|---|---|---|---|---|---|---|---|---|---|---|
| Temp. (°C) | Time (min) | Temperatures (°C) | Rotation speed (rpm) | Temp. (°C) | Time (min) | |||||
| Different WS size with fixed 10 wt% | ||||||||||
| 1st | WS/PP | — | — | — | 150 | 10/90 | 165–160–155 | 35 | 165 | 12 |
| WS/PP | — | — | — | 212 | 10/90 | 165–160–155 | 35 | 165 | 12 | |
| WS/PP | — | — | — | 300 | 10/90 | 165–160–155 | 35 | 165 | 12 | |
| Different WS loading content in PP matrix with fixed best WS size 212 µm | ||||||||||
| 2nd | WS/PP | — | — | — | 212 | 20/80 | 165–160–155 | 35 | 165 | 12 |
| WS/PP | — | — | — | 212 | 30/70 | 165–160–155 | 35 | 165 | 12 | |
| WS/PP | — | — | — | 212 | 40/60 | 165–160–155 | 35 | 165 | 12 | |
| Different NaOH concentrations with best WS loading 20 wt% and best WS size 212 µm | ||||||||||
| 3rd | WS/PP | 3 | 80 | 20 | 212 | 20/80 | 165–160–155 | 35 | 165 | 12 |
| WS/PP | 5 | 80 | 20 | 212 | 20/80 | 165–160–155 | 35 | 165 | 12 | |
| WS/PP | 7 | 80 | 20 | 212 | 20/80 | 165–160–155 | 35 | 165 | 12 | |
Microwave model Samsung Solo Mikrowelle 23-l.
3 Preparation of WS/PP composites
Two extrusion and hot pressing processes were used to produce all dosages of WS/PP composites. First, a functionalized and designed homemade single screw extruder was created to fulfill the standard specifications for extruder machines. It is constructed from sturdy materials that will not damage the extruded material when exposed to heat or mechanical stress. In addition to precise control temperature and cooling system for saving required temperature. Lastly, every component can be taken apart for maintenance or to make cleaning easier after every use [32]. This extruder was set to specific temperature and rotation speed conditions as shown in Table 2, including the fixing temperature for the three areas (feed, melt preheat, and melt conveyance) from 165–160–155°C and speed 35 rpm. The low-temperature compounding (LTC) method was adopted, with the extruder temperature set at 165°C (feed range), which is close to the melting point of the PP matrix [33]. Cutting the producing filament by extruder into small pellets in order to prepare it for pressing in the hot press was done using a specialized cutter known as the “Thermo Electron Cutter Pelletizing Lab Line” (Figure 6).
Thermo Electron Cutter Pelletizing Lab Line.
Second, the traditional homemade hot press machine has been designed and functionalized to meet the standard requirements of hot press machines [34]. During the construction, suitable materials were selected that can withstand mechanical and thermal loads. In addition, it was equipped with precise control for temperature, pressure, and compression time as well as an effective cooling system to control temperature [35,36,76]. This hot press was set to specific temperature and time conditions, as shown in Table 2. The temperature and time were 165°C and 12 min, and the pressing load was also set to 6 tons [33,77,78,79,80,81,82]. The mold was designed using 304 stainless steel with dimensions 190 × 195 × 3 mm for width, length, and thickness. This mold was used to prepare a sheet of WS/PP composites for each step shown in Table 2 before cutting into tensile, bending, and impact specimens according to the ASTM standards D638-02a, D790, and D256, respectively.
4 Mechanical properties of WS/PP composites
4.1 Tensile test
Tensile testing is an evaluation of the performance of materials and their tolerance to external forces and deformations. After attaching the specimen to the fixture with upper and lower jaws, an axial tensile force is applied to determine the strain and maximum stress the material can withstand before failure. The results are then analyzed, a relationship between stress–strain is drawn, and mechanical properties such as maximum tensile strength, Young’s modulus, and elongation at break are extracted. Major variables affecting tensile properties include fiber and matrix type, fiber-to-matrix ratio, fiber orientation, manufacturing process, operating conditions, and fiber size [37]. Therefore, in the present work, the tensile properties were tested at a crosshead speed of 5 mm/min using an Instron machine, model LARYEE (China) (Figure 7). Based on the ASTM D638-02a standard [35], five samples were cut for each WS/PP composite type for each step shown in Table 2. An electric vibration scroll saw model “RYOBI® RSW1240G, China” (Figure 8) was used to cut all samples (tensile, flexural, and impact samples) of the WS/PP composites.
Instron machine, model LARYEE (China).
Electric vibration scroll saw model “RYOBI® RSW1240G, China”.
4.2 Flexural test
Designing lightweight, robust structures requires a precise grasp of composite materials’ behavior under load, which can only be achieved by studying their flexural properties. The test involves applying a concentrated load to a sample to determine the material’s flexural strength. This helps assess the hardness and durability of composite materials. There are two types of bending tests: the four-point bending test, where the load is distributed between two points on the specimen supported by two points, and the three-point bending test, which applies a load in the middle of the specimen supported by two points. The three-point test is easy and quick to perform, while the four-point test offers better load distribution and provides more accurate data on central bending areas. The main variables that affect bending properties include fiber and matrix type, layer sequence, particle distribution, and sample thickness. The expected results of this investigation include load–displacement curves and identification of failure locations, which will help improve the design of composite materials and their engineering use [37,38,39]. Therefore, the bending test in the current work was carried out as a three-point bending test and with a crosshead speed of two millimeters per minute. The Instron machine model “LARYEE, China” was used to determine the bending properties for all dosages of WS/PP composites. The measurements were carried out according to ASTM D790 [40,41] and therefore indicate that the dimensions of the sample were 130 × 13 × 3 mm.
4.3 Impact test
Impact testing determines the ability of materials to withstand sudden and high loads. This helps develop products that can withstand harsh conditions and impacts. The results of this inspection include measuring the energy absorbed during mechanical impact. These results represent the cracking and breaking resistance of the material under sudden loads, which helps improve the design of structures and increase their reliability in practical applications. There are two types of impact testing: The first is the Charpy impact test, which provides a quick and direct assessment of the energy absorbed when the sample breaks and helps determine the durability of materials at different temperatures. The second is the directional crack test (Izod impact test), which is used to determine the strength of materials by measuring the energy required to break a sample suspended at one end, and is usually used at used to evaluate plastics and metals [37,42]. The current work employed the impact test of the Izod to investigate the absorbed energy of all dosages of WS/PP composites. The specimens’ dimensions were 63 × 13 × 3 mm made to follow ASTM standard D256 [43]. The “XJU-22 Izod” (Figure 9), a 5.5J pendulum impact machine, was laboring to inspect the impact energy of all dosages of WS/PP composites. These energies were divided on the cross-sectional area of each sample to get the impact strength by (kJ/m2).
Impact machine XJU-22 Izod.
Accurate results can be obtained by taking into account both the errors that can be introduced into the testing system and its overall quality. In order to determine the range of accuracy, Table 3 presents the tensile, flexural, and impact properties of the PP, untreated, and treated WS/PP composites along with statistical analysis, including the average, standard deviation, and error.
Mechanical properties for PP, untreated, and treated WS/PP composites with different NaOH concentrations and statistical analyses
| Sample | PP, untreated and treated with different NaOH% of the WS/PP composites | Tensile strength (MPa) | Tensile modulus (GPa) | Tensile strain (%) |
|---|---|---|---|---|
| 1 | Pure PP | 25.268 | 1.15 | 4.324 |
| 2 | Pure PP | 27.824 | 1.43 | 4.597 |
| 3 | Pure PP | 24.293 | 1.32 | 3.434 |
| 4 | Pure PP | 31.969 | 1.21 | 3.527 |
| 5 | Pure PP | 26.146 | 1.38 | 4.318 |
| Average | 27.1 | 1.3 | 4.04 | |
| Standard error | 1.3486 | 0.0629 | 0.2344 | |
| Standard deviation error | 3.0157 | 0.1406 | 0.5241 | |
| Error | −1.6670 | −0.0777 | −0.2897 | |
| 1 | 20%, 212 µm WS/PP | 34.746 | 2.011 | 1.936 |
| 2 | 20%, 212 µm WS/PP | 39.254 | 2.597 | 1.841 |
| 3 | 20%, 212 µm WS/PP | 29.67 | 2.337 | 1.468 |
| 4 | 20%, 212 µm WS/PP | 29.273 | 1.903 | 1.974 |
| 5 | 20%, 212 µm WS/PP | 31.657 | 2.808 | 1.336 |
| Average | 32.92 | 2.3312 | 1.711 | |
| Standard error | 1.8562 | 0.1709 | 0.1297 | |
| Standard deviation error | 4.1507 | 0.3821 | 0.2900 | |
| Error | −2.2944 | −0.2112 | −0.1603 | |
| 1 | 3% WS/PP | 29.495 | 3.261 | 3.211 |
| 2 | 3% WS/PP | 34.102 | 3.642 | 4.181 |
| 3 | 3% WS/PP | 36.659 | 3.719 | 3.338 |
| 4 | 3% WS/PP | 38.339 | 2.86 | 3.275 |
| 5 | 3% WS/PP | 37.405 | 3.018 | 3.995 |
| Average | 35.2 | 3.3 | 3.6 | |
| Standard error | 1.5905 | 0.1684 | 0.2024 | |
| Standard deviation error | 3.5566 | 0.3766 | 0.4525 | |
| Error | −1.9660 | −0.2082 | −0.2502 | |
| 1 | 5% WS/PP | 36.303 | 6.234 | 2.106 |
| 2 | 5% WS/PP | 39.745 | 5.41 | 1.8 |
| 3 | 5% WS/PP | 41.895 | 4.544 | 2.592 |
| 4 | 5% WS/PP | 28.493 | 6.712 | 2.129 |
| 5 | 5% WS/PP | 31.064 | 5.1 | 2.373 |
| Average | 35.5 | 5.6 | 2.2 | |
| Standard error | 2.5332 | 0.3899 | 0.1337 | |
| Standard deviation error | 5.6643 | 0.8717 | 0.2989 | |
| Error | −3.1311 | −0.4819 | −0.1653 | |
| 1 | 7% WS/PP | 43.471 | 6.548 | 1.014 |
| 2 | 7% WS/PP | 37.901 | 6.67 | 0.85 |
| 3 | 7% WS/PP | 30.074 | 7.54 | 1.015 |
| 4 | 7% WS/PP | 42.674 | 8.992 | 0.933 |
| 5 | 7% WS/PP | 30.33 | 8.2 | 0.72 |
| Average | 36.89 | 7.59 | 0.9064 | |
| Standard error | 2.8920 | 0.4622 | 0.0557 | |
| Standard deviation error | 6.4668 | 1.0335 | 0.1245 | |
| Error | −3.5748 | −0.5713 | −0.0688 |
| Sample | PP, untreated, and treated with different NaOH% of WS/PP composites | Flexural strength (MPa) | Flexural modulus (MPa) | Impact strength (kJ/m2) |
|---|---|---|---|---|
| 1 | Pure PP | 40.82 | 378.79 | 54.449 |
| 2 | Pure PP | 39.748 | 332.67 | 46.123 |
| 3 | Pure PP | 47.485 | 431.48 | 42.18 |
| 4 | Pure PP | 38.648 | 387.31 | 45.999 |
| 5 | Pure PP | 33.299 | 419.75 | 42.249 |
| Average | 40 | 390 | 46.2 | |
| Standard error | 2.2748 | 22.1126 | 2.2345 | |
| Standard deviation error | 5.0866 | 49.4453 | 4.9966 | |
| Error | −2.8118 | −27.3327 | −2.7620 | |
| 1 | 20%, 212 WS/PP | 29.58 | 590.608 | 67.868 |
| 2 | 20%, 212 WS/PP | 29.519 | 557.587 | 60.447 |
| 3 | 20%, 212 WS/PP | 25.619 | 772.17 | 71.961 |
| 4 | 20%, 212 WS/PP | 22.347 | 612.375 | 53.922 |
| 5 | 20%, 212 WS/PP | 23.435 | 743.26 | 67.402 |
| Average | 26.1 | 655.2 | 64.32 | |
| Standard error | 1.5036 | 42.9947 | 3.1905 | |
| Standard deviation error | 3.3622 | 96.1392 | 7.1343 | |
| Error | −1.8586 | −53.1444 | −3.9437 | |
| 1 | 3% NaOH WS/PP | 27.516 | 619.459 | 89.304 |
| 2 | 3% NaOH WS/PP | 25.954 | 537.411 | 68.384 |
| 3 | 3% NaOH WS/PP | 26.91 | 710.676 | 81.528 |
| 4 | 3% NaOH WS/PP | 22.99 | 480.563 | 68.093 |
| 5 | 3% NaOH WS/PP | 20.83 | 615.891 | 88.941 |
| Average | 24.84 | 592.8 | 79.25 | |
| Standard error | 1.2687 | 39.2452 | 4.7050 | |
| Standard deviation error | 2.8368 | 87.7550 | 10.5206 | |
| Error | −1.5681 | −48.5097 | −5.8157 | |
| 1 | 5% NaOH WS/PP | 29.068 | 846.255 | 86.577 |
| 2 | 5% NaOH WS/PP | 22.175 | 747.471 | 124.465 |
| 3 | 5% NaOH WS/PP | 30.109 | 609.141 | 122.319 |
| 4 | 5% NaOH WS/PP | 28.701 | 655.688 | 90.341 |
| 5 | 5% NaOH WS/PP | 23.597 | 885.445 | 111.798 |
| Average | 26.73 | 748.8 | 107.1 | |
| Standard error | 1.6021 | 53.0780 | 7.9287 | |
| Standard deviation error | 3.5823 | 118.6861 | 17.7291 | |
| Error | −1.9803 | −65.6081 | −9.8004 | |
| 1 | 7% NaOH WS/PP | 31.463 | 719.57 | 145.434 |
| 2 | 7% NaOH WS/PP | 24.745 | 626.76 | 103.143 |
| 3 | 7% NaOH WS/PP | 30.082 | 728.91 | 136.052 |
| 4 | 7% NaOH WS/PP | 33.846 | 671.34 | 104.762 |
| 5 | 7% NaOH WS/PP | 31.439 | 685.42 | 127.609 |
| Average | 30.315 | 686.4 | 123.4 | |
| Standard error | 1.5187 | 25.2548 | 8.4291 | |
| Standard deviation error | 3.3959 | 56.4716 | 18.8481 | |
| Error | −1.8772 | −31.2167 | −10.4190 |
5 Physicochemical characterization of WS/PP composites
FTIR has been extensively used to investigate the effect of treated methods on the WS and to examine the nature of adhesion between WS and the neat PP in all WS/PP composites. Using an FTIR device model (Bruker Tensor 27 IR – Systems Chemistry, Germany), the FTIR spectra of untreated and treated WS powder as well as WS/PP composites with and without treatment were recorded in the range of 4,000–400 cm−1. To investigate the chemical band representing the influence of the treatment techniques on the WS powder and WS/PP composites, the samples were supplied as fine powder.
Using a scanning electron microscope (SEM) for microstructural analysis of WS/PP composites (Vegan SEM TESCAN, Czech Republic), the fracture zone of tensile test samples of WS/PP composites was examined to analyze how WS withstands mechanical loads and load distributions WS/PP structure, with emphasis on the changes in microstructure due to WS treatment. This analysis was carried out on pure PP, untreated, and treated WS/PP composites with different NaOH concentrations. The samples were attached to an aluminum holder with a special adhesive and then coated with a gold layer about 5 nm thick. The test was carried out in a high vacuum with an acceleration voltage of 20 kV and a working distance of (2.892) mm.
The X-ray diffraction (XRD) spectra of pure PP, treated, and untreated WS/PP composites were analyzed to explain the changes in the crystal patterns and the effects of WS treatment on the structure of WS/PP composites. Therefore, the XRD model XRD-6000, Shimadzu, Japan, was used under the conditions of a copper X-ray tube target with a value of 40 kV, a divergence slit and a scattering slit of 1 degree and a receiving slit of 0.3 mm. A current of 30 mA and a 2-theta range between 10 and 80° with a scan distance of 0.04° and a scan speed of 10 degrees/min, with a specific time value of 0.24 s.
6 Results and discussions
6.1 Influence of different sizes and loadings of WS powder on the tensile properties of WS/PP composites – First strategy
The sizes and loadings of WS powder were investigated in the development of new WS/PP composites by studying their effects on the mechanical properties of new WS/PP composites, which were achieved by specifying the extrusion operating conditions. As (temperature 165–160–155°C and rotation speed 35 rpm) and compression molding process; (temperature 165°C, load 6 tons, and time 12 min) to determine the best WS powder size and WS powder loading in all dosages of WS/PP composites to achieve the highest tensile strength.
The effects of WS powder sizes on the tensile properties of the WS/PP composites were investigated at a WS powder loading of 10 wt% in WS/PP composites with three different WS powder sizes (150, 212, and 300 μm) (Figure 10). The tensile strength, tensile modulus, and tensile strain values for the PP and WS/PP composites with different WS powder sizes of 150, 212, and 300 μm were found to be 27.1, 28.3, 30.2, and 26.89 MPa, tensile modulus 1.3, 2, 2.15, and 1.93 GPa, and tensile strain 4.04, 2.16, 1.84, and 1.7%, respectively. The increase in tensile strength values from 28.3 MPa at 150 μm to 30.2 MPa at 212 μm could be due to the good distribution and adaptation of the surfaces of the WS particles to the PP matrix [33,44], but decreased to 26 MPa for the WS, powder size at 300 μm due to the lack of surface area of the particles and their agglomeration, which weakens the structure of the WS/PP composites [33]. Consequently, the tensile modulus values increased slightly with increasing the size of the WS powder to 1.3, 2, 2.15, and 1.93 GPa at 150, 212, and 300 μm. Conversely, the tensile strain values for 150, 212, and 300 μm were reduced to 2.16, 1.84, and 1.7%, respectively, with the highest strain value remaining at 4.04% for the PP matrix [45,46]. The WS/PP composites were stiffer and had lower tensile strain because the modulus of WS powder was larger than the modulus of PP [47]. Therefore, the best WS powder size was 212 μm, which reached a tensile strength of 30.2 MPa.
Effects of WS powder sizes on the tensile properties of WS/PP composites.
The effects of WS powder loadings on the tensile properties of the WS/PP composites were examined at an optimum WS powder size of 212 μm in WS/PP composites with four different WS powder loadings (10, 20, 30, and 40 wt%) (Figure 11). The tensile strength, tensile modulus, and tensile strain values for the PP and WS/PP composites with different WS powder loadings of 10, 20, 30, and 40 wt% were documented to be 27.1, 30.2, 32.92, 31.41, and 26.06 MPa, tensile modulus 1.3, 2.15, 2.33, 2.26, and 2.11GPa and tensile strain 4.04, 1.84, 1.711, 1.52, and 1.44%, respectively. It was detected that the 20 wt% WS powder loading in WS/PP composite achieved the highest tensile strength value of 32.92 MPa, among other composites that recorded the lowest values. This higher tensile strength was attributed to an enhanced WS/PP interfacial bonding, where the WS powder works as a carrier of load in a PP matrix, which is consistent with earlier work [11,48]. However, the deterioration of 10 wt% WS/PP composites may be due to the lack of WS powder loading in the PP matrix, resulting in a lack of load transfer in the matrix [49]. Furthermore, increasing the WS powder loading to more than 20 wt% can lead to a larger WS powder surface area in the PP matrix, resulting in WS agglomeration and blocking of stress transfer, as demonstrated by old work [50]. The tensile modulus exhibited a comparable pattern to the tensile strength, indicating the same causes and justifications as previously stated.
Effects of WS powder loadings on the tensile properties of WS/PP composites.
Conversely, the tensile strain for the WS/PP composites with different WS powder loadings showed a sudden decrease from 4.04% for PP to 1.84% for 10 wt% WS/PP composites; after that, there was a continuous gradual decrease in tensile strain for the other WS/PP composites as proved by previous works [45,46]. Finally, the best WS powder size and powder loading in the PP matrix were documented at 212 μm and 20 wt%, which achieved a tensile strength of 32.92 MPa.
6.2 Investigation of the effect of microwave and alkali treatment methods on the mechanical properties of WS/PP composites-second strategy
To create and develop new sustainable and environmentally friendly WS/PP composites, the effects of the microwave and alkali treatment methods on the mechanical properties of the WS powder and WS powder-reinforced PP matrix were examined. This was achieved by defining the following parameters for microwave operation: 20 min, 80°C, 80 rpm stirring speed, and 2.2 GHz microwave frequency, with varying solution NaOH concentrations of 3, 5, and 7%.
Figure 12 shows the effect of the treatment method for different NaOH concentrations on the tensile strength of sustainable WS/PP composites. The tensile strength values of PP, untreated (212 μm and 20 wt% WS/PP composite) and treated WS/PP composites with different NaOH concentrations of 3, 5, and 7% were 27.1, 32.92, 35, 2, 35.5, and 36.89 MPa. Obviously, the tensile strength values of the treated WS/PP composites gradually increased with increasing concentrations of NaOH solution with an optimum value of 36.89 MPa. While the natural WS powder contains hydroxyl groups from cellulose and lignin that reduce the activity towards the PP matrix, these modifications may activate these groups to introduce new moieties that effectively chief to chemically join with the PP matrix for improving WS powder strength, fitness, and WS–PP matrix adhesion. This is because the combination of the microwave and alkali treatment methods cleaned the WS powder surface, also improved the chemistry on the WS powder surface, poorer the wetness uptake, and even more surface roughness [19,51]. Therefore, microwave and alkali treatment activates the hydroxyl groups in the WS powder, improves the chemical interaction with the PP matrix, increases the strength and cohesion of the composite, reduces moisture absorption, and improves the surface of the powder.
Effects of different NaOH concentrations on the tensile strength of WS/PP composites.
Figure 13 displays the effect of the treatment method for different NaOH concentrations on the tensile modulus of WS/PP composites. The tensile modulus values of untreated WS/PP composite was 2.3312 GPa and of treated WS/PP composites with different concentrations of 3, 5, and 7% NaOH solutions were 3.3, 5.6, and 7.59 GPa, respectively. The increase in tensile modulus of WS/PP composites after treatment with microwave alkali treatment methods compared to the untreated WS-reinforced PP matrix could be due to a reduction in WS powder dimensions after alkali treatment by removal of hemicellulose, lignin, oil, and impurities [52]. This change in the structure of the WS powder increased the crystallinity by concentrating the cellulose in the WS structure [51,53].
Effects of different NaOH concentrations on the tensile modulus of WS/PP composites.
Figure 14 exhibits the effect of the treatment method for different NaOH concentrations on the tensile strain of WS/PP composites. The tensile strain values of untreated WS/PP composite were 1.711% and of treated WS/PP composites with different concentrations of 3, 5, and 7% NaOH solutions were 3.6, 2.2, and 0.9%, respectively. For WS/PP composites treated with 3% NaOH solution, there was a dramatic increase in tensile strain to 3.6%, which may be due to the smoothing of the WS powder surface caused by treatment processes, which leads to the sliding movement of the particles in WS/PP composite structure [51]. Then, there was a gradual decrease in elongation to 2.2% for the WS/PP composite treated with 5% NaOH solution, followed by a continuous decrease to 0.9% for the WS/PP composite treated with 7% NaOH solution. The decrease in tensile strain in the treated WS/PP composites supported the improvement in tensile strength, which resulted from the improvement in surface roughness due to the treatment method, which resulted in good interaction between WS powder and the PP matrix. This improvement in interaction may be due to the WS acting as a carrier to transfer the load throughout the entire WS/PP composite structure. In addition, the WS has a lower tensile strain than the tensile strain of the PP matrix, so this behavior affects the structure of the WS/PP composites by reducing the tensile strain of the WS/PP composites after treatment with NaOH solutions [45,46].
Effects of different NaOH concentrations on the tensile strain of WS/PP composites.
Figure 15 shows the effect of the treatment method for different NaOH concentrations on the flexural strength of WS/PP composites. The flexural strength values of PP and untreated WS/PP composite were 40 and 26.1 MPa and of treated WS/PP composites with different concentrations of 3, 5, and 7% NaOH solutions were 24.48, 26.73, and 30.315 MPa, respectively. Except for the composite treated with 3% NaOH solution, which had the lowest flexural strength among the PP, untreated, and treated WS/PP composites, it is obvious that the flexural strength of the alkali-treated composites was increased compared to the untreated composites. When 3% NaOH solution treatment was applied to WS powder-reinforced PP composites, the results showed no improvement, which may be because the NaOH concentration was still not enough to improve the flexural properties of the WS/PP composite [54]. Conversely, at all doses of untreated and treated WS/PP composites, there was a reduction in flexural strength compared to the PP matrix. The internal structure of pure PP is completely homogeneous, giving it higher flexural strength compared to treated and untreated WS/PP composites that contain WS powder as a reinforcing additive. WS powder may be agglomerated or associated with some reaction impurities (in treated composites) or large amounts of lignin, hemicelluloses, oil, wax, or other natural impurities, which lead to this deterioration in the flexural strength of treated and untreated WS/PP composites, respectively [54].
Effects of different NaOH concentrations on the flexural strength of WS/PP composites.
Figure 16 shows the effect of the treatment method for different NaOH concentrations on the flexural modulus of WS/PP composites. The flexural modulus values of PP and untreated WS/PP composite were at 390 and 655.2 MPa, and of treated WS/PP composites with different concentrations of 3, 5, and 7% NaOH solutions were at 592.8, 748.8, and 686.4 MPa, respectively. There was a variation in flexural modulus for PP, untreated, and treated WS/PP composites. Therefore, the maximum flexural modulus was recorded for a composite treated with a 5% NaOH solution of a WS-reinforced PP matrix, while the lowest flexural modulus was documented for a PP matrix. A reduction in the flexural modulus of the PP matrix results from insufficient reinforcement in the absence of WS powder, making the PP matrix less stiff and more susceptible to deformation under load [54]. Meanwhile, treating a WS-reinforced PP matrix with a 5% NaOH solution increased the effective surface area and improved the interfacial bonding between the WS powder and the PP matrix, which increased the flexural modulus due to the WS powder rearrangement and improved elasticity [54].
Effects of different NaOH concentrations on the flexural modulus of WS/PP composites.
Figure 17 shows the effect of the treatment method for different NaOH concentrations on the impact strength of WS/PP composites. The impact strength values of PP and untreated WS/PP composite were 46.2 and 64.32 kJ/m2 and of treated WS/PP composites with different concentrations of 3, 5, and 7% NaOH solutions were 79.25, 107.1, and 123.4 kJ/m2, respectively. The impact strength of the WS/PP composites gradually increased and reached a peak value for the composite treated with 7% NaOH solution. This improvement in impact strength may be reflected in a good interaction between treated WS powder and the PP matrix to improve impact properties. Chemical treatment improved the structure of WS by removing all amorphous components such as lignin, hemicelluloses, and other impurities, which provided PP with the opportunity to replace these removed materials and achieve interaction between PP and the structure of WS powder. The treatment process allowed the WS powder to act as a carrier of the energy released by the test hammer [55], and thus a huge improvement in the impact strength of the sustainable environmentally friendly WS/PP composites was achieved.
Effects of different NaOH concentrations on the impact strength of WS/PP composites.
The FTIR analysis of the structure in WS and changes in the structure of the treated WS with different NaOH concentrations of 3, 5, and 7% are shown in Figure 18, along with their major band data in Table 4. The analysis shows an O–H stretch band at 3,299–3,320 cm−1 and a C–H band at 2,782–2,946 cm−1, recognized as C–H (alkyl) by of [56] for untreated and treated WS, contained in cellulose, hemicellulose, and lignin, as shown in Table 4. The C–H bend vibrated for the untreated and treated WS as bands 445, 449, 441, and 455 cm−1, which demonstrated the increase in cellulose content in all dosages of the WS [57]. Stretch bands were recorded at 1,050, 1,036, and 1,034 cm−1 (primary alcohol C–O) of untreated and treated WS with 3 and 5% NaOH solution, respectively. Conversely, this band was absent in treated WS with the 7% NaOH solution, which may be due to the increasing NaOH concentrations that removed lignin content [58]. The aromatic ring C═C was shown as stretching bands at a constant value of 1,602 cm−1 for all treated groups of WS and for untreated WS at band 1,596 cm−1 respectively. This showed that lignin removal had a constant value in all treated WS, compared to the untreated ones, which recorded the lowest value [58]. For ether C–O–C, there was a stretching band at 1,251, 1,247, and 1,251 cm−1 for treated WS with 3, 5, and 7% NaOH, but the absence of this band was observed for untreated WS. This proved that the cellulose content was concentrated in the treated WS compared to the untreated one [58]. Therefore, the chemical and physical treatments promised a good improvement in the structure of WS, which may lead to the improvement of the mechanical properties of the prepared new WS/PP composites.
FTIR of untreated and treated WS with different NaOH concentrations.
FTIR bands of untreated and treated WS with different NaOH concentrations
| Functional group | Wavenumber (cm−1) | Vibrational mode | Untreated WS | Treated WS with 3% NaOH | Treated WS with 5% NaOH | Treated WS with 7% NaOH | The part that includes the functional group | Ref. |
|---|---|---|---|---|---|---|---|---|
| C–H bending | 450–400 | Bending | 445 | 449 | 441 | 455 | Cellulose | [56] |
| C–O (Primary alcohol) | 1,050–1,040 | Stretching | 1,050 | 1,036 | 1,034 | — | Cellulose | [58] |
| C–O–C (Ether) | 1,000–1,320 | Stretching | — | 1,251 | 1,247 | 1,251 | Cellulose | [58] |
| C═C Aromatic ring | 1,500–1,650 | Stretching | 1,596 | 1,602 | 1,602 | 1,602 | Lignin | [58] |
| C–H (Alkyl) | 2,750–2,950 | Stretching | 2,782 | 2,782 | 2,784 | 2,784 | Cellulose and hemicellulose | [56] |
| 2,856 | 2,858 | 2,862 | 2,864 | |||||
| — | — | 2,944 | 2,946 | |||||
| O–H (Hydroxyl) | 3,100–3,650 | Stretching | 3,310 | 3,312 | 3,320 | 3,299 | Cellulose and lignin | [59] |
Figure 19 shows the FTIR spectra for pure PP, untreated (0% NaOH), and treated (3, 5, and 7% NaOH) WS/PP composites, as well as the primary band data presented in Table 5. Figure 10 shows primary alcohol C–O groups of the untreated WS/PP composites at band 1,043 cm−1, whereby these bands are missing for PP and all differently treated WS/PP composites according to NaOH concentrations. The disappearance of this band can be attributed to the fact that hemicellulose, one of the main components of WS, was severely affected by alkali treatment. Hemicellulose contains C–O groups and undergoes hydrolysis during alkali treatment, breaking the glycosidic bonds in its PP structure [58]. The peaks at bands 1,208 and 1,294 cm−1 represented ether C–O–C and were recorded for the untreated and treated WS/PP composites, as shown in Table 5. Growing ether C–O–C increased flexibility and toughness due to the improved deformability of the composites, while it increased by reducing hardness and brittleness due to the lack of bonds that support expansion and elasticity [58]. The C═C aromatic ring was recorded between 1,428 and 1,602 cm−1 for the treated and untreated WS-reinforced PP composites. The growing pecks for the aromatic produced improving WS/PP composite structure [58]. The O–H (hydroxyl) values decreased after treatment due to the removal or decomposition of components containing these groups, such as hemicellulose and cellulose. Low O–H (hydroxyl) values lead to reduced flexibility and shock absorption capacity, which increases the hardness of the material and makes it more brittle, because the hydroxyl group contributes to hydrating the material and providing hydrogen bonds that enhance cohesion and flexibility [59]. As a result, it was anticipated that the chemical and physical treatments would significantly improve the WS/PP composites’ structure, which could enhance the mechanical properties of the newly created WS/PP composites.
FTIR of untreated and treated WS/PP with different NaOH concentrations.
FTIR bands of untreated and treated WS with different NaOH concentrations reinforced WS/PP composites
| Functional group | Wavenumber (cm−1) | Vibrational mode | Pure PP | Untreated WS/PP | Treated WS/PP with 3% NaOH | Treated WS/PP with 5% NaOH | Treated WS/PP with 7% NaOH | Ref. |
|---|---|---|---|---|---|---|---|---|
| C–O (primary alcohol) | 1,050–1,040 | Stretching | — | 1,043 | — | — | — | [58] |
| C–O–C (ether) | 1,000–1,320 | Stretching | 1,208 | 1,208 | 1,210 | 1,210 | 1,210 | [58] |
| 1,292 | 1,294 | 1,292 | 1,292 | 1,292 | ||||
| C═C aromatic ring | 1,500–1,650 | Stretching | 1,510 | 1,465 | — | 1,432 | 1,428 | [58] |
| 1,602 | 1,602 | 1,604 | 1,604 | |||||
| O–H (hydroxyl) | 3,100–3,650 | Stretching | — | 3,361 | 3,347 | 3,324 | 3,336 | [60] |
Figure 20 shows the SEM images of PP, treated, and untreated WS/PP composites. Figure 20a shows SEM images of the fracture zone of pure PP, which show a rough and cracked surface with isolated small cavities. This type of fracture indicates brittle behavior under tensile stress. The lack of load transfer auxiliary WS resulted in irregular cracks, reflecting the material’s limited ability to distribute stresses within the PP matrix.
SEM of (a) PP matrix, (b) untreated WS/PP, (c) treated WS/PP with 3%, (d) treated WS/PP with 5%, and (e) treated WS/PP with 7% NaOH concentrations.
Figure 20b shows SEM images of the fracture zone of untreated WS/PP composite samples. A relative improvement in stress distribution was observed compared to pure polymer. WS acted as a reinforcing agent, resulting in better load distribution within the matrix. However, the images showed clear voids created by the fibers being pulled out of the matrix structure (PP), indicating a weakness in the interfacial bond between the WS and the PP matrix. These cavities represent weak points that contribute to the reduced effectiveness of stress tolerance.
Figure 20c shows SEM images of the fracture zone of the WS/PP sample treated with 3% sodium hydroxide solution. SEM images of the sodium hydroxide-treated samples showed a significant improvement in the microstructure of the interfacial bond between the fibers and the matrix compared to the untreated sample, with a relative reduction in the size of the voids created by fiber drawing (Figure 20b).
Figure 20d showed that increasing the concentration of caustic soda to 5% resulted in the removal of some impurities from the WS surface, which was reflected in the improvement of the WS surface. This resulted in stronger cohesion between the WS and PP matrix, which helped to increase the effectiveness of load transfer and improve interfacial bonding. The voids became less visible and more homogeneous, indicating an improvement in tensile strength.
Figure 20e shows SEM images of the fracture zone of the WS/PP composites treated with 7% NaOH. The SEM images of this sample showed the best improvement in microstructure as the WS surface became cleaner and could interact better with the polymer matrix, resulting in an increase in interconnections and a significant reduction in voids. This improvement in microstructure was reflected in an improvement in the mechanical properties of the WS/PP composite material, as the WS was better able to resist stresses and transfer loads within the material, resulting in a reduction in crack propagation, resulting in increased tensile strength.
Figure 21 shows the XRD analysis of PP, treated, and untreated WS/PP composites. The XRD spectrum of pure PP showed broad diffraction peaks, reflecting the semi-crystalline nature of PP. The appearance of broad peaks reflects ordered and disordered regions within the PP and indicates a structure characterized by a mixture of small crystals and amorphous spaces. Due to the lack of crystalline regularity, this structure leads to limited mechanical properties.
XRD analysis of PP matrix, untreated, treated WS/PP with 3, 5, and 7% NaOH concentrations.
Conversely, the XRD spectrum of untreated WS/PP showed clear diffraction peaks at certain angles 2θ (14, 17, 19, and 22), indicating the incorporation of WS into the PP matrix. The peaks generated by WS did not change significantly compared to pure PP, indicating that WS did not significantly affect the crystal structure of the WS/PP composite. However, a slight increase in crystal density was observed, indicating a slight improvement in mechanical properties due to the presence of fibers.
As for the XRD of WS/PP composites treated with different NaOH concentrations, WS/PP composites treated with 3% NaOH solution showed increased crystallinity and improved crystal ordering, resulting in improved mechanical properties led. When treated with a 5% NaOH solution, sharper crystalline peaks appeared, which improved load transfer and increased stiffness and tensile strength. Treatment with 7% NaOH solution showed the highest crystal density, which strengthened the bonds between WS and PP matrix and increased the resistance to mechanical stress.
6.3 Comparison of mechanical properties of treated WS/PP composites and ASAC
The microwave and alkali treatment techniques enhanced the mechanical characteristics of the resulting WS/PP composites. The PP matrix reinforced with WS, treated with a 7% NaOH solution (WS7Comp), had the best mechanical properties. Therefore, the mechanical properties of WS7Comp were compared with a real car part (ASAC) to prove its applicability and demonstrate the successful design of WS/PP, as a new type of sustainable and environmentally friendly composite.
Figure 22 shows the final comparison of all studied mechanical properties (tensile, bending, and impact properties) of the sustainable, environmentally friendly new WS/PP composites (WS7Comp) and ASAC as evidence of the possible applications of WS/PP composites. It was found that the mechanical property values of WS7Comp were close to the actual mechanical property values for the application chosen as the target of the study, with the superior improvement in the impact strength for the WS7Comp recorded at 123.4 kJ/m2.
Comparison of the mechanical behavior for the WS/PP composite and the ASAC.
7 Conclusions
The development of a sustainable, environmentally friendly WS/PP composite was successfully carried out, and the size of the WS powder, the loading of the WS powder, and the treatment concentrations of the NaOH were optimized accordingly. The FTIR analysis confirmed the best-optimized parameters for preparation and treatment, such as WS powder size of 212 μm, WS powder loading of 20 wt%, and NaOH concentration of 7%, respectively, to accomplish the best promising tensile strength, flexural strength, and impact strength values of 36.89 MPa, 30.315 MPa, and 123.4 kJ/m2, accordingly. The SEM analysis showed that the NaOH-microwave treatment methods of WS improved the interfacial bonding with the PP matrix, resulting in improved stress distribution and reduction of weak areas, thus improving the overall mechanical properties of the WS/PP composites. The XRD analysis showed that treating WS with alkaline microwave treatment methods effectively improved the crystal structure and mechanical properties of WS-reinforced PP composites, which significantly increased the efficiency of the WS/PP composites. Comparison of WS7Comp with the ASAC showed significant improvements in mechanical properties with a significant superior improvement in impact strength over the target material. Thus, this advancement highlights the importance of introducing innovative processing methods such as microwaves with alkali to improve the mechanical performance of composites and make them a powerful option for industrial applications that require materials with improved mechanical properties. This recommends that the current study opens new horizons for the use of processed bio-additives in producing high-performance and environmentally sustainable composite materials.
Acknowledgment
This study was supported by the University of Technology-Iraq (UOT)/Ministry of Higher Education and Scientific Research (MOHEASR). In addition, the author would like to thank the Department of Materials Engineering, the Center for Nanotechnology and Advanced Materials, and the University of Babylon for all their support.
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Funding information: Author states no funding involved.
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Author contribution: The author confirms the sole responsibility for the conception of the study, presented results and manuscript preparation.
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Conflict of interest: Author states no conflict of interest.
References
[1] Abedsoltan H. Applications of plastics in the automotive industry: Current trends and future perspectives. Polym Eng Sci. 2024;64:929–50.10.1002/pen.26604Search in Google Scholar
[2] Prasad V, Alliyankal Vijayakumar A, Jose T, George SC. A comprehensive review of sustainability in natural-fiber-reinforced polymers. Sustainability. 2024;16:1223.10.3390/su16031223Search in Google Scholar
[3] Dejene BK. False banana (Enset Ventricosum) fibers: An emerging natural fiber with distinct properties, promising potentials, challenges and future prospects–A critical review. J Nat Fibers. 2024;21:2311303.10.1080/15440478.2024.2311303Search in Google Scholar
[4] Chatterjee D, Dhaigude AS. Browse, read, shop, share: social commerce and how to tap it. SPJIMR Management practice insights; 2024.Search in Google Scholar
[5] Sileo A, Bonacina M. The automotive industry: when regulated supply fails to meet demand. The case of Italy; 2024.10.2139/ssrn.4696375Search in Google Scholar
[6] Lee CC, Olasehinde‐Williams G. Does economic complexity influence environmental performance? Empirical evidence from OECD countries. Int J Financ Econ. 2024;29:356–82.10.1002/ijfe.2689Search in Google Scholar
[7] Hensher DA. The greening of the passenger car might not deliver such positive sustainability news–So what do we have to do? Transp Res Part A: Policy Pract. 2024;179:103932.10.1016/j.tra.2023.103932Search in Google Scholar
[8] More AP. Flax fiber–based polymer composites: a review. Adv Compos Hybrid Mater. 2022;5:1–20.10.1007/s42114-021-00246-9Search in Google Scholar
[9] Malladi A, Kaliappan S, Natrayan L, Mahesh V. Effectiveness of thermal and mechanical properties of jute fibers under different chemical treatment for automotive interior trim. SAE Technical Paper; 2024. p. 0148–7191.10.4271/2024-01-5008Search in Google Scholar
[10] Salman Hassan M, Salih WM. Mechanical performance of CO2 and autoclave cured date palm fiber reinforced eco-mortar composites. Eng Technol J. 2016;34:2754–65.10.30684/etj.34.14A.18Search in Google Scholar
[11] Mohammed A, Bachtiar D, Rejab MR, Hasany S, Siregar J. Influence of different sugar palm fiber content on the tensile, flexural, impact, and physicochemical properties of eco-friendly thermoplastic polyurethane. Theor Found Chem Eng. 2019;53:454–62.10.1134/S0040579519030072Search in Google Scholar
[12] Mahardika M, Zakiyah A, Ulfa SM, Ilyas RA, Hassan MZ, Amelia D, et al. Recent developments in oil palm empty fruit bunch (OPEFB) fiber composite. J Nat Fibers. 2024;21:2309915.10.1080/15440478.2024.2309915Search in Google Scholar
[13] Abdul Monem ZM, Oleiwi JK, Hamad QA. The effect of peanut and walnut shells powders on tensile and microstructure of the PMMA for prosthetic denture. Eng Technol J. 2021;39:196–205.10.30684/etj.v39i2A.1730Search in Google Scholar
[14] Cârstea V. Crises in the automotive industry. Rom Econ Bus Rev. 2023;18:34–40.Search in Google Scholar
[15] Al-Shathr BS, Gorgis IN, Motlog RF. Effect of using plastic and rubber wastes as fine aggregate on some properties of cement mortar. Eng Technol J. 2016;34:1688–99.10.30684/etj.34.8A.18Search in Google Scholar
[16] Faheed NK. Advantages of natural fiber composites for biomedical applications: a review of recent advances. Emergent Mater. 2024;7:1–13.10.1007/s42247-023-00620-xSearch in Google Scholar
[17] Pepi C, Pipistrelli ME, Gioffrè M. Random modeling of hemp fibers mechanical properties. Compos Part A: Appl Sci Manuf. 2024;183:108203.10.1016/j.compositesa.2024.108203Search in Google Scholar
[18] Mohanta S, Mahalik P, Hota GP, Sahoo BB, Pradhan SS, Mohanty SP. Influence of surface‐treatment of bamboo fiber on the physico‐mechanical properties of bamboo fiber composites with virgin and recycled high‐density polyethylene. Polym Compos. 2024;45:914–23.10.1002/pc.27825Search in Google Scholar
[19] Mohammed A, Bachtiar D, Rejab M, Siregar J. Effect of microwave treatment on tensile properties of sugar palm fibre reinforced thermoplastic polyurethane composites. Def Technol. 2018;14:287–90.10.1016/j.dt.2018.05.008Search in Google Scholar
[20] Kumar S, Dang R, Manna A, Sharma S, Dwivedi SP, Kumar A, et al. Effect of chemically treated kenaf fiber on the mechanical, morphological, and microstructural characteristics of PLA-based sustainable bio-composites fabricated via direct injection molding route. Biomass Convers Biorefinery. 2023;1–17.10.1007/s13399-023-04916-0Search in Google Scholar
[21] Guo J, He S, Liu X, Xu M, Liang J, Chu Y. Hydrophobic modification of walnut shell biomass-derived porous carbon for the adsorption of VOCs at high humidity. Chem Eng J. 2024;488:150792.10.1016/j.cej.2024.150792Search in Google Scholar
[22] Shahi Shavvon R, Qi H-L, Mafakheri M, Fan P-Z, Wu H-Y, Bazdid Vahdati F, et al. Unravelling the genetic diversity and population structure of common walnut in the Iranian Plateau. BMC Plant Biol. 2023;23:201.10.1186/s12870-023-04190-2Search in Google Scholar PubMed PubMed Central
[23] Fukasawa R, Miyazawa T, Abe C, Bhaswant M, Toda M. Functional components of walnuts: A review focusing on native and cultivated species. Food Sci Technol Res. 2024;30:1–12.10.3136/fstr.FSTR-D-23-00093Search in Google Scholar
[24] Maulood P, Darwesh D. Soil quality index models for assessing walnut orchards in northern Erbil Province, Iraq. Pol J Environ Stud. 2020;29:1275–85.10.15244/pjoes/108686Search in Google Scholar
[25] Karagöz İ. Production and characterization of sustainable biocompatible PLA/walnut shell composite materials. Polym Bull. 2024;81:1–21.10.1007/s00289-024-05247-4Search in Google Scholar
[26] Karagöz İ, Mutlu D, Çavuşoğlu A, Çelebi M, Ceylan Ö. A comprehensive study on the effect of small rates of walnut shell and talc fillers on the thermal, mechanical, and morphological properties of epoxy hybrid composites. Biomass Convers Biorefinery. 2024;1–12.10.1007/s13399-024-05660-9Search in Google Scholar
[27] Hossain MT, Shahid MA, Mahmud N, Habib A, Rana MM, Khan SA, et al. Research and application of polypropylene: a review. Discov Nano. 2024;19:2.10.1186/s11671-023-03952-zSearch in Google Scholar PubMed PubMed Central
[28] Maddah HA. Polypropylene as a promising plastic: A review. Am J Polym Sci. 2016;6:1–11.Search in Google Scholar
[29] Altun T, Pehlivan E. Removal of Cr (VI) from aqueous solutions by modified walnut shells. Food Chem. 2012;132:693–700.10.1016/j.foodchem.2011.10.099Search in Google Scholar
[30] PETRONAS. Connect with Us; 2024. https://www.petronas.com/connect-with-us.Search in Google Scholar
[31] Kadri E, Dhahri K, Barillé R, Rasheed M. Novel method for the determination of the optical conductivity and dielectric constant of SiGe thin films using Kato-Adachi dispersion model. Phase Transit. Feb. 2021;94(2):65–76. 10.1080/01411594.2020.1832224.Search in Google Scholar
[32] Alshalal I, Al-Zuhairi HMI, Abtan AA, Rasheed M, Asmail MK. Characterization of wear and fatigue behavior of aluminum piston alloy using alumina nanoparticles. J Mech Behav Mater. Jan. 2023;32(1). 10.1515/jmbm-2022-0280.Search in Google Scholar
[33] Bouras D, Fellah M, Barille R, Abdul Samad M, Rasheed M, Awjan Alreshidi M. Properties of MZO/ceramic and MZO/glass thin layers based on the substrate’s quality. Opt Quantum Electron. Dec. 2023;56(1):104. 10.1007/s11082-023-05778-6.Search in Google Scholar
[34] Bouras D, Rasheed M. Comparison between CrZO and AlZO thin layers and the effect of doping on the lattice properties of zinc oxide. Opt Quantum Electron. Oct. 2022;54(12):824. 10.1007/s11082-022-04161-1.Search in Google Scholar
[35] Ahcen Keziz M, Heraiz F, Sahnoune F, Rasheed M. Characterization and mechanisms of the phase’s formation evolution in sol-gel derived mullite/cordierite composite. Ceram Int. Oct. 2023;49(20):32989–3003. 10.1016/j.ceramint.2023.07.275.Search in Google Scholar
[36] Al-Darraji M, Jasim S, Salah Aldeen O, Ghasemian A, Rasheed M. The effect of LL37 antimicrobial peptide on FOXE1 and lncRNA PTCSC 2 genes expression in colorectal cancer (CRC) and normal cells. Asian Pac J Cancer Prev. Oct. 2022;23(10):3437–42. 10.31557/apjcp.2022.23.10.3437.Search in Google Scholar PubMed PubMed Central
[37] Sellam M, Rasheed M, Azizii S, Saidani T. Improving photocatalytic performance: Creation and assessment of nanostructured SnO2 thin films, pure and with nickel doping, using spray pyrolysis. Ceram Int. Mar. 2024;50(12):20917–35. 10.1016/j.ceramint.2024.03.094.Search in Google Scholar
[38] Ahcen Keziz M, Rasheed M, Heraiz F, Sahnoune, Latif A. Structural, morphological, dielectric properties, impedance spectroscopy and electrical modulus of sintered Al6Si2O13–Mg2Al4Si5O18 composite for electronic applications. Ceram Int. Dec. 2023;49(23):37423–34. 10.1016/j.ceramint.2023.09.068.Search in Google Scholar
[39] Jaber AS, Ismael M, Rashid T, Sarhan MA, Rasheed M, Sala IM. Comparesion the electrical parameters of photovoltaic cell using numerical methods. Eureka: Phys Eng. Jul. 2023;27(4):29–39. 10.21303/2461-4262.2023.002770.Search in Google Scholar
[40] Assoudi N, Chaabani A, Rasheed M, Walha I, Dhahri E, Alawsi T, et al. Comparative examination of the physical parameters of the sol gel produced compounds La0.5Ag0.1Ca0.4MnO3 and La0.6Ca0.3Ag0.1MnO3. Opt Quantum Electron. Jul. 2022;54(9):556. 10.1007/s11082-022-03927-x.Search in Google Scholar
[41] Darraji M, Saqban L, Mutar T, Rasheed M, Hussein A. Association of candidate genes polymorphisms in Iraqi patients with chronic kidney disease. J Adv Biotechnol Exp Therapeutics. 2022;6(1):687. 10.5455/jabet.2022.d147.Search in Google Scholar
[42] Rasheed M, Saleem MM, Marzoog TR, Taki MM, Bouras D, Hashim IA. Effect of caffeine-loaded silver nanoparticles on minerals concentration and antibacterial activity in rats. J Adv Biotechnol Exp Therapeutics. Jan. 2023;6(2):495–5. 10.5455/jabet.2023.d144.Search in Google Scholar
[43] Kherifi D, Keziz A, Rasheed M, Oueslati A. Thermal treatment effects on Algerian natural phosphate bioceramics: A comprehensive analysis. Ceram Int. May 2024. 10.1016/j.ceramint.2024.05.317.Search in Google Scholar
[44] Hussein AJ, Al-Darraji MN, Rasheed M, Sarhan MA. A study of the characteristics of wastewater on the Euphrates River in Iraq. IOP Conference Series: Earth and Environmental Science. Vol. 1262, No. 2; Dec. 2023. p. 022005. 10.1088/1755-1315/1262/2/022005.Search in Google Scholar
[45] Hussein AJ, Al-Darraji MN, Rasheed M. A study of physicochemical parameters, heavy metals and algae in the Euphrates river, Iraq. IOP Conference Series. Earth and Environmental Science. Vol. 1262, No. 2; Dec. 2023. p. 022007. 10.1088/1755-1315/1262/2/022007.Search in Google Scholar
[46] Mohammed AA, Bachtiar D, Siregar JP, Rejab MR, Hasany SF. Physicochemical study of eco-friendly sugar palm fiber thermoplastic polyurethane composites. BioResources. 2016;11:9438–54.10.15376/biores.11.4.9438-9454Search in Google Scholar
[47] Rosato DV, Rosato DV, v Rosato M. Plastic product material and process selection handbook. Elsevier; 2004.10.1016/B978-185617431-2/50005-0Search in Google Scholar
[48] Landel RF, Nielsen LE. Mechanical properties of polymers and composites. Boca Raton: Taylor@Francis Group, CRC press; 1993.10.1201/b16929Search in Google Scholar
[49] Standard A. Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials. ASTM D790. Annual book of ASTM standards; 1997.Search in Google Scholar
[50] A. Standard, D 256. Standard test methods for determining the sized pendulum Impact resistance of plastics. West Consonance (PA): ASTM International; 2010.Search in Google Scholar
[51] Taghipoor H, Mirzaei J. Statistical predicting and optimization of the tensile properties of natural fiber bio-composites. Polym Bull. 2023;80:13217–41.10.1007/s00289-023-04713-9Search in Google Scholar
[52] Abdellah MY, Sadek MG, Alharthi H, Abdel-Jaber GT. Mechanical, thermal, and acoustic properties of natural fibre-reinforced polyester. Proc Inst Mech Eng, Part E: J Process Mech Eng. 2024;238:1436–48.10.1177/09544089231157638Search in Google Scholar
[53] El-Shekeil YA, Salit MS, Abdan K, Zainudin ES. Development of a new kenaf bast fiber-reinforced thermoplastic polyurethane composite. BioResources. 2011;6(4).10.15376/biores.6.4.4662-4672Search in Google Scholar
[54] Espinach F, Vilaseca F, Tarrés Q, Delgado-Aguilar M, Aguado R, Mutjé P. An alternative method to evaluate the micromechanics tensile strength properties of natural fiber strand reinforced polyolefin composites. The case of hemp strand-reinforced polypropylene. Compos Part B: Eng. 2024;273:111211.10.1016/j.compositesb.2024.111211Search in Google Scholar
[55] Ahad NA. A review: relation on natural fiber loading to the tensile properties of TPU composites. Int J Biomass Renew. 2021;10:1–7.10.61762/ijbrvol10iss1art10271Search in Google Scholar
[56] Chen X, Wang X, Luo X, Chen L, Li Y, Xu J, et al. Bamboo as a naturally-optimized fiber-reinforced composite: Interfacial mechanical properties and failure mechanisms. Compos Part B: Eng. 2024;279:111458.10.1016/j.compositesb.2024.111458Search in Google Scholar
[57] Mylsamy B, Shanmugam SKM, Aruchamy K, Palanisamy S, Nagarajan R, Ayrilmis N. A review on natural fiber composites: Polymer matrices, fiber surface treatments, fabrication methods, properties, and applications. Polym Eng Sci. 2024.10.1002/pen.26713Search in Google Scholar
[58] Widodo E, Tjahjanti PH. Characterization of sansevieria fiber with NaOH alkalization to increase tensile strength. In IOP Conference Series: Earth and Environmental Science; 2022. p. 012030.10.1088/1755-1315/1104/1/012030Search in Google Scholar
[59] Cai M, Takagi H, Nakagaito AN, Katoh M, Ueki T, Waterhouse GI, et al. Influence of alkali treatment on internal microstructure and tensile properties of abaca fibers. Ind Crop Products. 2015;65:27–35.10.1016/j.indcrop.2014.11.048Search in Google Scholar
[60] Zidi S, Miraoui I. Mechanical and morphological analysis of cellulose extracted from sisal fibers and their effect on bio-based composites mechanical properties. Funct Compos Struct. 2024;6:015008.10.1088/2631-6331/ad2fe5Search in Google Scholar
[61] Gani A, Ibrahim M, Ulmi F, Farhan A. The influence of different fiber sizes on the flexural strength of natural fiber-reinforced polymer composites. Results Mater. 2024;21:100534.10.1016/j.rinma.2024.100534Search in Google Scholar
[62] Narayana VL, Rao LB. A brief review on the effect of alkali treatment on mechanical properties of various natural fiber reinforced polymer composites. Mater Today: Proc. 2021;44:1988–94.10.1016/j.matpr.2020.12.117Search in Google Scholar
[63] Chen H, Xu X, Gong S, Wang D, Zhou Y, Wang Z. A comparison of ether-and alkyl-imidazolium-based ionic liquids diluted with CH3CN: A combined FTIR and DFT study. J Mol Liq. 2020;313:113542.10.1016/j.molliq.2020.113542Search in Google Scholar
[64] Mueller M, Grosse I, Jacobasch H-J, Sams P. Surfactant adsorption and water desorption on thin cellulose films monitored by in-situ ATR-FTIR spectroscopy. Tenside Surfactants Deterg. 1998;35:354–8.10.1515/tsd-1998-350508Search in Google Scholar
[65] Wang L, Li J, Chen Y, Yang H, Shao J, Zhang X, et al. Investigation of the pyrolysis characteristics of guaiacol lignin using combined Py-GC× GC/TOF-MS and in-situ FTIR. Fuel. 2019;251:496–505.10.1016/j.fuel.2019.04.061Search in Google Scholar
[66] Smith B. The CO bond, Part I: Introduction and the infrared spectroscopy of alcohols; 2017.Search in Google Scholar
[67] Rasheed M, Shihab S, Alabdali O, Rashid A, Rashid T. Finding roots of nonlinear equation for optoelectronic device. J Phys: Conf Ser. Sep. 2021;1999(1):012077. 10.1088/1742-6596/1999/1/012077.Search in Google Scholar
[68] Rasheed M, Alabdali O, Shihab S, Rashid A, Rashid T. On the solution of nonlinear equation for photovoltaic cell using new iterative algorithms. J Phys: Conf Ser. Sep. 2021;1999(1):012078. 10.1088/1742-6596/1999/1/012078.Search in Google Scholar
[69] Rasheed M, Nuhad Al-Darraji M, Shihab S, Rashid A, Rashid T. The numerical calculations of single-diode solar cell modeling parameters. J Phys: Conf Ser. Jul. 2021;1963(1):012058. 10.1088/1742-6596/1963/1/012058.Search in Google Scholar
[70] Rasheed M, Al-Darraji MN, Shihab S, Rashid A, Rashid T. Solar PV modelling and parameter extraction using iterative algorithms. J Phys: Conf Ser. Jul. 2021;1963(1):012059. 10.1088/1742-6596/1963/1/012059.Search in Google Scholar
[71] Kadri E, Krichen M, Mohammed R, Zouari A, Khirouni K. Electrical transport mechanisms in amorphous silicon/crystalline silicon germanium heterojunction solar cell: impact of passivation layer in conversion efficiency. Opt Quantum Electron. Nov. 2016;48(12):1–15. 10.1007/s11082-016-0812-7.Search in Google Scholar
[72] Shihab S, Rasheed M, Alabdali O, Abdulrahman AA. A novel predictor-corrector hally technique for determining the parameters for nonlinear solar cell equation. J Phys: Conf Ser. May 2021;1879(2):022120. 10.1088/1742-6596/1879/2/022120.Search in Google Scholar
[73] Rasheed M, Mohammed OY, Shihab S, Al-Adili A. Explicit numerical model of solar cells to determine current and voltage. J Phys: Conf Ser. Mar. 2021;1795(1):012043. 10.1088/1742-6596/1795/1/012043.Search in Google Scholar
[74] Rasheed M, Shihab S, Mohammed OY, Al-Adili A. Parameters estimation of photovoltaic model using nonlinear algorithms. J Phys: Conf Ser. Mar. 2021;1795(1):012058. 10.1088/1742-6596/1795/1/012058.Search in Google Scholar
[75] Rasheed M, SuhaShihab, Alabdali O, Hassan HH. Parameters extraction of a single-diode model of photovoltaic cell using false position iterative method. J Phys: Conf Ser. May 2021;1879(3):032113. 10.1088/1742-6596/1879/3/032113.Search in Google Scholar
[76] Bouras D, Rasheed M, Barille R, Aldaraji MN. Efficiency of adding DD3+ (Li/Mg) composite to plants and their fibers during the process of filtering solutions of toxic organic dyes. Opt Mater. Sep. 2022;131:112725. 10.1016/j.optmat.2022.112725.Search in Google Scholar
[77] Al Zubaidi FN, Asaad LM, Alshalal I, Rasheed M. The impact of zirconia nanoparticles on the mechanical characteristics of 7075 aluminum alloy. J Mech Behav Mater. Jan. 2023;32(1):20220302. 10.1515/jmbm-2022-0302.Search in Google Scholar
[78] Sarhan MA, Shihab S, Kashem BE, Rasheed M. New exact operational shifted pell matrices and their application in astrophysics. J Phys: Conf Ser. May 2021;1879(2):022122. 10.1088/1742-6596/1879/2/022122.Search in Google Scholar
[79] Alabdali O, Shihab S, Rasheed M, Rashid T. Orthogonal Boubaker-Turki polynomials algorithm for problems arising in engineering. 3rd International Scientific Conference of Alkafeel University (ISCKU 2021); 2022. 10.1063/5.0066860.Search in Google Scholar
[80] Enneffatia M, Rasheed M, Louatia B, Guidaraa K, Shihab S, Barillé R. Investigation of structural, morphology, optical properties and electrical transport conduction of Li0.25Na0.75CdVO4 compound. J Phys: Conf Ser. Mar. 2021;1795(1):012050. 10.1088/1742-6596/1795/1/012050.Search in Google Scholar
[81] Saidi W, Hfaidh N, Rasheed M, Girtan M, Megriche A, Maaoui ME. Effect of B2O3 addition on optical and structural properties of TiO2 as a new blocking layer for multiple dye sensitive solar cell application (DSSC). RSC Adv. Jan. 2016;6(73):68819–26. 10.1039/c6ra15060h.Search in Google Scholar
[82] Bouras D, Fellah M, Mecif A, Barillé R, Obrosov A, Rasheed M. High photocatalytic capacity of porous ceramic-based powder doped with MgO. J Korean Ceram Soc. 2023;60(1):155–68. 10.1007/s43207-022-00254-5.Search in Google Scholar
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Articles in the same Issue
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Articles in the same Issue
- Research Articles
- Evaluation of the mechanical and dynamic properties of scrimber wood produced from date palm fronds
- Performance of doubly reinforced concrete beams with GFRP bars
- Mechanical properties and microstructure of roller compacted concrete incorporating brick powder, glass powder, and steel slag
- Evaluating deformation in FRP boat: Effects of manufacturing parameters and working conditions
- Mechanical characteristics of structural concrete using building rubbles as recycled coarse aggregate
- Structural behavior of one-way slabs reinforced by a combination of GFRP and steel bars: An experimental and numerical investigation
- Effect of alkaline treatment on mechanical properties of composites between vetiver fibers and epoxy resin
- Development of a small-punch-fatigue test method to evaluate fatigue strength and fatigue crack propagation
- Parameter optimization of anisotropic polarization in magnetorheological elastomers for enhanced impact absorption capability using the Taguchi method
- Determination of soil–water characteristic curves by using a polymer tensiometer
- Optimization of mechanical characteristics of cement mortar incorporating hybrid nano-sustainable powders
- Energy performance of metallic tubular systems under reverse complex loading paths
- Enhancing the machining productivity in PMEDM for titanium alloy with low-frequency vibrations associated with the workpiece
- Long-term viscoelastic behavior and evolution of the Schapery model for mirror epoxy
- Laboratory experimental of ballast–bituminous–latex–roving (Ballbilar) layer for conventional rail track structure
- Eco-friendly mechanical performance of date palm Khestawi-type fiber-reinforced polypropylene composites
- Isothermal aging effect on SAC interconnects of various Ag contents: Nonlinear simulations
- Sustainable and environmentally friendly composites: Development of walnut shell powder-reinforced polypropylene composites for potential automotive applications
- Mechanical behavior of designed AH32 steel specimens under tensile loading at low temperatures: Strength and failure assessments based on experimentally verified FE modeling and analysis
- Review Article
- Review of modeling schemes and machine learning algorithms for fluid rheological behavior analysis
- Special Issue on Deformation and Fracture of Advanced High Temperature Materials - Part I
- Creep–fatigue damage assessment in high-temperature piping system under bending and torsional moments using wireless MEMS-type gyro sensor
- Multiaxial creep deformation investigation of miniature cruciform specimen for type 304 stainless steel at 923 K using non-contact displacement-measuring method
- Special Issue on Advances in Processing, Characterization and Sustainability of Modern Materials - Part I
- Sustainable concrete production: Partial aggregate replacement with electric arc furnace slag
- Exploring the mechanical and thermal properties of rubber-based nanocomposite: A comprehensive review
- Experimental investigation of flexural strength and plane strain fracture toughness of carbon/silk fabric epoxy hybrid composites
- Functionally graded materials of SS316L and IN625 manufactured by direct metal deposition
- Experimental and numerical investigations on tensile properties of carbon fibre-reinforced plastic and self-reinforced polypropylene composites
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