Volume 15, Issue 6

The weak impact properties of carbon fiber-reinforced plastics (CFRPs) are due to their laminated structure, thus limiting the use of these materials in various automotive applications even though they provide weight savings as compared with metal materials. In this study, core shell rubbers (CSRs), which are known for their excellent dispersion characteristics, were selected as an impact modifier and CFRPs incorporated with CSRs were fabricated using the vacuum-assisted resin transfer molding process to enhance their impact properties. CFRPs with highly reinforced carbon fibers of 72–74 wt.% were prepared without voids as confirmed by morphological and thermogravimetric data. The impact strength of the CFRPs was improved by up to 87.5%, depending on the increase in CSR content, but their tensile properties were not reduced, indicating that these properties were predominantly determined by the continuous reinforcement of carbon fibers. Therefore, CSRs are an effective impact modifier for improving the impact properties of CFRPs. These findings will help in increasing the use of CFRPs as automotive structural materials.

Microcapsules containing a glycidyl ester-type epoxy resin were successfully synthesized by in situ polymerization, with poly(melamine-urea-formaldehyde) as the shell material and diglycidyl 1,2-cyclohexanedicarboxylate (DGCHD) as the core substance. Scanning electron microscopy was performed to investigate the surface morphology and shell wall thickness of the microcapsule. The fabrication, diameters and thermal decomposition behavior of the resultant microcapsules were studied by means of Fourier transform infrared spectroscopy, laser particle size analysis, and thermogravimetric analysis (TGA), respectively. Results indicated that the highest loading of DGCHD in the as-prepared microcapsules was about 89.1 wt.% and that the mean diameter of the capsules was in the range of 50–130 μm, which can be adjusted by changing the feeding mass ratio of the core/shell material and emulsifying rate, respectively. TGA results showed that the microencapsulated DGCHD degraded in two distinguishable stages.

By electron spin resonance, ultraviolet-visible and infrared spectroscopy, and chromatography, calorimetry, elemental analysis and gravimetric methods, we determined the low-temperature impact of molecular chlorine on monomers and the free radicals that spontaneously form. The radicals that formed initiated the polymerization and chlorination reactions that occurred during the mixture of chlorine+monomer, which were prepared at 77 K and heated to 300 K. For the monomers that were in solid state at 300 K, the reactions proceeded in the temperature range near the chlorine melting point (170 K), whereas for the monomers that were in the liquid state at 300 K, the reactions occurred in the temperature range near the monomer melting point.

A thermoplastic elastomeric blend was introduced based on high-density polyethylene and styrene-butadiene rubber (SBR). The morphology of the blend system was found to change from two-phase to co-continuous, depending on the polyethylene (PE) concentration. The thermo-mechanical measurements showed that, at the PE concentrations, which seemed to have a co-continuous morphology, the SBR inclusions were very fine. The fineness of the SBR domains resulted in a 20° depression of the glass transition temperature ( T g ) of the SBR phase. This was attributed to the smooth interfaces at which the SBR chain sensed a higher free volume as compared with that in bulk SBR. A model correlating thin polymer thickness to the T g of the confined polymer in the films was employed to correlate SBR domain size to the experimental T g measured. The adjusting parameters A =129 and δ =1.45 were successfully used to fit the experimental data.

We aim to utilise the tea tree ( Melaleuca alternifolia) fibre, a waste from the distillation process, as a reinforcement or filler in tapioca starch (TS) composites. Fabrication of tea tree fibre-reinforced TS composites was successfully developed using a casting method. The physical, thermo-chemical, and mechanical properties were tested in order to get the characterisation of the composites. From the mechanical test, the addition of 5% (v/v) tea tree fibre as a filler improved the tensile strength of the TS composites up to 34.39% in tea tree leaf-reinforced TS composites (TTL/TS), 82.80% in tea tree branch-reinforced TS composites (TTB/TS) and 203.18% in tea tree trunk-reinforced TS composites (TTT/TS). The water absorption and swelling of all tea tree fibre-reinforced composites decreased compared to those of TS composites. Most importantly, all parts of the tea tree waste, namely, the tea tree leaf, tea tree branch and tea tree trunk, have additional potential value as fibres that can act as a reinforcement in developing a green biocomposite.

Carboxymethyl cellulose and hydrogel beads produced from sugar cane bagasse (SCB) and palm kernel cake (PKC) were characterised, and the ability of the hydrogel beads to encapsulate and protect the probiotic bacteria of Lactobacillus acidophilus (LA-5) under simulated gastrointestinal conditions was investigated. Encapsulation with SCB and PKC hydrogel beads was performed with 87.4% and 80.9% efficiency, respectively, compared with that with alginate hydrogel beads, which had 75.0% efficiency. LA-5 free cells and those encapsulated in alginate hydrogel beads showed no survival. LA-5 cells encapsulated in SCB and PKC hydrogel beads retained high survival under stomach conditions of pH 2 after 1.5 h (>6 log CFU/ml) and 3 h (>4 log CFU/ml). However, no survival of cells was observed under colon conditions of pH 7.5 after 24 h. SCB and PKC hydrogel beads were able to protect the cells against the pH conditions of the stomach but not of the colon.

Biocomposites from starch and cellulose fibers have gained renewed interest as environmentally friendly materials and as biodegradable renewable resources for a sustainable development. In this study, natural fibers were extracted from a Mediterranean saltbush ( Atriplex halimus ) plant found abundantly in North Africa. The composites were prepared by a solution casting method from corn starch using 0–15 wt.% of micro-cellulose fibers as a filler. The structure of the composites was investigated by Fourier transform infrared spectroscopy. The physical properties of the composites were determined by mechanical tensile tests, thermogravimetric analysis and water absorption. The results showed that higher fiber content raised the elastic modulus by 92% and the temperature of degradation by up to 355°C. Optical microscopy revealed a good adhesion between the matrix and the fibers owing to their chemical similarities. Water uptake measurements showed that the composites had a much better water resistance and a more hydrophobic character than pure thermoplastic starch films. Biodegradability tests confirmed that the prepared composites are an environmentally safe material suited for different applications.

Soju industrial waste is an important biomass resource. The present study aimed to utilize soju industrial waste for silica extraction, and residual ash (RA) as a low cost adsorbent for the removal of methylene blue (MB) from aqueous solution. A high percentage of pure amorphous nanosilica was obtained from soju industrial waste ash by the acid dissolution-precipitation process. The synthesized nanosilica and the RA were characterized well using various techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), and field-emission electron microscopy with energy dispersive spectroscopy (EDS). The amorphous nature of nanosilica and its 99% purity were confirmed by XRD and EDS profiles, respectively. Transmission electron microscopy (TEM) micrographs show the nano range (14–18 nm) of synthesized silica. The adsorption capacity of RA was evaluated as a function of initial dye concentration, pH, and contact time. The sorption equilibrium data were modeled with isotherms; the Langmuir isotherm model fits well with maximum monolayer adsorption capacity of 232.5 mg/g at 30°C. The adsorption kinetics was best fitted with the pseudo-second-order model, suggesting that chemisorption plays a significant role in the adsorption process. The results showed that soju industrial waste is a potential waste for silica extraction and that its byproducts are effective adsorbents.

In this study, the solution method was used to prepare polyamide 11/polyvinylidene difluoride (PA11/PVDF) blend films. The crystal phase compositions and microstructures of the blends were studied by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy analysis. Additionally, the dielectric properties of the PA11/PVDF blends, with different ratios and concentrations, were tested. The results indicated that the solution method is more propitious in forming β crystals during the preparation of the PA11/PVDF blend films compared with the melt blending method. The amount of β crystals present in PVDF was dependent on the ratio of dimethyl sulfoxide (DMSO) and H 2 O. Specifically, for the 5:95 ratio of DMSO/H 2 O precipitants, the PA11/PVDF (80:20) blend films prepared by the solution method had a high dielectric constant of 188.1 and a dielectric loss of 1.37.

Epoxy acrylate (EA) and tripropylene glycol diacrylate (TPGDA) are two main components of ultraviolet-curable coatings. In this study, the viscosity of EA-TPGDA binary mixtures at various mass ratios was measured by a rotational viscometer at temperatures between 298.15 and 313.15 K. The temperature dependence of the viscosity of the mixtures is discussed. An empirical correlation between the viscosity and the temperature was obtained based on the Andrade equation. The results indicated that the calculated viscosity values show a good agreement with experimental data. This will contribute to the evaluation of the rheological properties and provide a theoretical basis for the industrial application of coatings.