Band 30, Heft 3

The cardanol grafted onto polypropylene (CAPP) was prepared by reactive extrusion with polypropylene (PP) and natural renewable cardanol, which could improve the inherent defects of PP such as chemical inertness and hydrophobicity. Moreover, the cardanol grafted onto PP could resolve the degradation of PP during the process of reactive extrusion, storage and application. In this paper, the yield strength, tensile strength, elongation at break of modified and unmodified PPs were tested during the aging process. A possible aging mechanim of PP and anti-aging mechanism of cardanol grafted onto PP were proposed. Results showed that the initiator dicumyl peroxide caused the degradation of PP chains during the aging processing. After being aged for 24 h, the yield strength CAPP0 decreased from 28 MPa to 15 MPa and the elongation at break reduced by 795%. CAPPs possessed outstanding anti-aging performance owing to the cross-linking and entanglement of the side chains of cardanol grafted onto PP. The yield strength, tensile strength and the elongation at break of CAPP5 changed lightly even when it was in long-term irradiation for 480 h. The CAPPs had better anti-aging properties than the mixture of PP and 5% of cardanol. CAPP containing 3% of cardanol could effectively prevent the degradation of the main chain polypropylene.

Co-extruded films with up to 65 layers of two rheologically mismatched polymer systems – polystyrene/poly(methylmethacrylate) (PS/PMMA) and hard/soft thermoplastic polyurethanes (TPUs) – were successfully produced using a combination of a 9-layer feedblock, low-pressure drop multiplier dies, and external lubricants. Formation of viscoelastic instabilities was studied using a custom visualization and by finite element method (FEM) simulations of a standard multiplier. The results showed that the flow inside the standard multiplier die is highly non-uniform, with severe gradients in shear and normal stresses and viscous encapsulation occurring mainly in the initial multiplication stages where there is enough material available in the low-viscosity layers to proceed with the encapsulation. To mitigate layer degradation the standard 2- or 3-layer feedblock was replaced with a 9-layer one, thereby decreasing the thickness of each layer at the end of the feedblock. Also, subsequent layering was performed using a low flow resistance die. This new multiplier die yields a more uniform flow profile and imparts a more homogeneous thermo-mechanical history on the melt which results in an improved layer stability. Simulations showed that in the standard die the second normal-stress difference (N 2 ) responsible for elastic instabilities at the edges of the die are very high. These can be reduced by inducing slip at the wall resulting in be much improved layer uniformity and stability. This was accomplished experimentally via the use of external lubricants, and the resulting layered structure was indeed much better than was possible to achieve with the conventional multiplier dies.

In this study acrylated epoxidized flaxseed oil was synthesized and then characterized by spectroscopic techniques. Triglycerides are the main constituents of flaxseed oil and the carbon-carbon double bond is the reaction site for epoxidation. Flaxseed oil was epoxidized by adding formic acid and hydrogen peroxide. Acrylic acid was then added to produce acrylated epoxidized flaxseed oil (AEFO). The change in the structure of the fatty acids chain after the epoxidation and acrylation reactions was measured and characterized by Hydrogen nuclear magnetic resonance spectroscopy ( 1 H NMR) and Fourier transform infrared spectroscopy (FTIR). The FTIR spectra of epoxidized flaxseed oil and flaxseed oil shows the disappearance of the =C–H (3012 cm −1 ) and C=C (1654 cm −1 ) peaks. The FTIR spectra confirmed the formation of AEFO since the presence of hydroxyl group (–OH) was shown by the peak at 3455 cm −1 and the acrylate group (–CH=CH 2 ), which was indicated by the peaks at 1406, 984 and 812 cm −1 . The changes in peaks of the 1 H NMR spectra also confirmed the formation of AEFO. The number of acrylate groups/molecule of triglyceride was found to be 2.6 from 1 H NMR spectra.

Soju industrial biomass residue (SIBR) is a lignocellulosic agro-industrial biowaste available in large quantities in soju producing countries. In this study, an attempt was made to extract microcrystalline cellulose (MCC), a biopolymer from SIBR by controlled acid hydrolysis. X-ray diffraction analysis indicated the presence of cellulose I structure with two peaks around 2θ = 15 and 22.5° and increase in crystallinity after acid hydrolysis treatment. Fourier transform infrared analysis showed no significant chemical affect of the cellulose fragment. Thermo-gravimetric analysis reveals that the extracted MCC have a good thermal stability (319°C). Dynamic light scattering studies confirmed the presence of MCC in micro range (126.4 nm) which was supported by transmission electron microscopy. The results of this work are useful for extracting valuable and widely applicable cellulose, and help solve management of SIBR in terms of disposal and pollution problems.

Based on the different nucleation ability, different contents and proportions of the mixed nucleating agents were melt compounded with pure isotactic polypropylene resins employed in this work, selective β nucleating agent was a compound of pimelic acid and calcium stearate, the α nucleating agent was a type of dibenzylidene sorbitol derivative. The competition attributed to the different type of interactions between a nucleating agent and isotactic polypropylene molecular chains during crystallization was investigated in this research. For a low content of the mixed nucleating agents used, α nucleation dominated the crystallization behavior of isotactic polypropylene, while with an increase of the content of the mixed nucleating agents, the situation was reversed and β nucleation became dominant. In the β dominated region, both of the molecular chain and segmental motions were various with different nucleating agent proportion. Thus, the content and proportion of the components of the nucleating agents were the critical factors in the competition during crystallization.

This paper investigated and compared the thermal and flexural properties and water absorption of natural caulis spatholobi residue fibers reinforced PPC/CSRF composites. Polypropylene carbonate (PPC) was reinforced by caulis spatholobi residue fibers (CSRF) which had been pretreated by continuous steam explosion. The effect of fiber content (10 to 60 wt%) on the properties and water absorption of PPC/CSRF biodegradable composites was investigated. The thermal properties of PPC/CSRF composites indicated that the addition of CSRF could improve the thermal stability of the composites. The flexural strength and modulus of the composites were found to be improved as the content of fiber increased. From the SEM micrographs, it was found that a small amount of fibers were pulled out on fractured surfaces of the composites, showing good network structure between the fiber and PPC matrix. The water absorption amount of the composites increased with increasing the fiber content. This paper demonstrates that the incorporation of low-cost and biodegradable caulis spatholobi residue fiber into PPC provides a practical way to produce completely biodegradable and cost-competitive composites with good mechanical properties.

The work presents the results of experimental studies of selected mechanical properties of plasticized poly(vinyl chloride) extruded by a single-screw extruder with a modified feed section. The variable factors were: feed opening width, feed pocket depth in the extruder barrel and the rotational speed of the screw. The following parameters were studied: yield strength R eH (MPa), tensile strength R m (MPa), percentage total extension at maximum force ∊ m (%), Shore hardness H (°ShA). It was found that the increase in the depth of the pocket and the decrease in the width of the feed opening in the studied range increase mechanical properties (besides percentage total extension at maximum force). It was determined that the increase of the screw speed and the simultaneous displacement of both the axis and edge of the feed opening in relation to the plasticizing system axis towards the direction of revolutions of the screw is favorable.

The paper shows the capability of state-of-the-art models and software to predict the fiber orientation distribution (FOD) on injection molded parts with a complex and thick-walled geometry. Predictions by the standard Folgar-Tucker model and the Reduced Strain Closure model were compared to measurements of the fiber orientation distribution obtained by X-ray Computed Tomography. Measurements and simulations were performed under different processing conditions to investigate the influence of injection velocity and packing pressure on the FOD. It was found that the predicted fiber orientation is in good qualitative agreement with the measurements. The measured orientation shows a distinct shell-core structure with high alignment of the fibers in flow direction in the shell layer and a orientation perpendicular to the flow direction in the core layer. While the orientation in the shell layer is predicted fairly well, a significant deviation is found in the prediction of the orientation in the core layer.

Thermoplastic micro parts are commonly manufactured by the large-scale production technology of micro injection molding, with small wall thicknesses limiting the feasible flow length. In contrast, microthermoforming is an inexpensive technology to manufacture thin-walled microstructured parts, but connecting three-dimensional solid bodies, e.g. functional structures, is impossible. The novel combination of processing techniques, i.e. microthermoforming integrated in the injection molding process with dynamic mold temperature control enables the use of non-adhesive polymer melt to form thermoplastic films via back molding and employ adhesive melt to connect further structures. Additional heating the film with the back molding component represents a particular benefit in terms of reaching the required film temperature and leads to low temperatures prevailing in the mold. Simulative tools facilitate the understanding of film temperatures after back molding and can be used in a further step for the adaption of homogenous temperature distributions across areally distributed microstructures. Generally speaking, the technology is expected to allow for multifunctional, thin-walled microstructured parts produced in short cycle times.

Light diffusing polycarbonate samples were exposed to protons fluences at levels between 10 11 and 10 16 p/cm 2 . The variation of the refractive index and color intensity with the proton fluence has been studied. The results show that the polycarbonate samples acquire color changes under proton irradiation. Furthermore, thermogravimetric analysis has been performed. It was found that both the onset temperature and activation energy of thermal decomposition are affected by the proton fluencies owing to the degradation and crosslinking processes. Moreover, structural property studies using X-ray diffraction, intrinsic viscosity and Fourier transform infrared spectroscopy were performed.

In this article, a new technology is described to manufacture open cell thermoplastic foamed sheets with the aid of surface-quenching phenomenon during an extrusion process. As the gas laden polymer extrudate exits the slit die, its surface is rapidly quenched which results in freezing of cells on the surface, while the cells at the core continue to grow and leads to development of open-cellular microstructure at the core. Influence of chill roll temperature was found to be extremely significant in developing porous morphological attributes. Subsequently, synergistic effect of physical blowing agent (N 2 ) content and chill roll temperature was examined for their expansion ratio and foam thickness. Fascinatingly, with reduced chill roll temperatures open-cell microstructure and high expansion ratio was obtained although its thickness was observed to decrease. Further, influence of chill roll rotating speed on foam microstructure and expansion ratio was studied. Lower chill roll rotational speed resulted in development of open-cellular microstructure; while at higher speeds, closed cell morphology was obtained. The results coherently demonstrate that by controlling the chill roll temperatures; open-cellular microstructure can be developed in sheet extrusion foaming process.

Filler plays a significant role in determining the properties and behavior of particulate composites. In this experimental study, mechanical and tribological behaviors of sub-micron size cenospheres filled glass-polyester composites are investigated. Cenospheres and glass fiber-reinforced polyester composites are prepared by hand lay-up technique. Composites are fabricated by filling 10 wt.% and 20 wt.% of 800 nm and 200 nm size of cenosphere filler particulate respectively along with 40 wt.% of glass fiber. Glass polyester composite without filler is also prepared for proportional analysis. A series of dry sliding wear test are conducted on a pin-on-disc machine with three sliding velocities of 1.57, 2.62 and 3.66 m/s under three different normal loading of 20, 25 and 40 N for three sliding distances of 1000, 2500 and 4000 m respectively. A statistics-based design of experiments approach is used by using Taguchi's orthogonal arrays. Results reveal that mechanical properties and wear resistance of the composites increase with a decrease in the particle size. Artificial neural network (ANN) approach is also applied to the friction and wear data for subsequent validation. Finally, optimal factor settings are determined using genetic algorithm (GA).

DBSA (Dodecylbenzene sulfonic acid)/PSS (Polystyrene sulfonic acid) doped polypyrrole composites were synthesized by in-situ chemical oxidative polymerization method with 0 to 5°C reaction temperature for 24 h. The particle size distribution of DBSA and PSS doped polypyrrole composites were found at 78 nm, 66 nm, 85 nm, 120 nm and 173 nm for different weight ratios of PSS. The presence of sulfur and higher doping level was confirmed by energy dispersive X-ray analysis. The mass percentages of sulfur were found in 17.94%, 34.41%, 40.87%, 44.9% and 48.16% for various weight ratios of PSS. The SEM study shows the granular morphology and aggregation of polypyrrole composites. Thermal stability improves with higher concentration of PSS. FTIR study confirms the presence of dopants in the composite structure. The UV-study reveals the π→π* transition in benzenoid rings of DBSA and presence of PSS. The conductivity of polypyrrole composite increases maximum upto 2.5 wt% of PSS and then decreases with increasing PSS content.