Materials Science Forum Vol. 1070

Abstract: In the context of carbon neutrality, it is of good economic and ecological value to replace synthetic fibres with natural fibres as reinforcing materials in the preparation of composites. The effect of the hot pressing process parameters on the physical and mechanical properties of the LBF/PP composites was further investigated. The distribution of LBF in the composites was observed by CT. The experimental results show that the hemicellulose content of the BF decreases and the lignin content decreases after the alkali treatment. The mechanical properties of the LBF/PP composites were better at a hot pressing temperature of 180°C, a hot pressing pressure of 8 MPa, a hot pressing time of 15 min and a mass fraction of 70% LBF, with bending strength and bending modulus reaching 226.1 MPa and 15.1 GPa respectively. CT results show that the fibres are evenly distributed in the composites and that the hot pressing process allows the molten PP to penetrate the pores of the LBF surface, forming a good physical and mechanical bond. These composites can be used in various applications such as construction, automotive, consumer goods etc. They are considered to be a suitable alternative to solid plastic products and materials.

Abstract: In this paper, ECO-friendly titanium magnesium catalyst with high activity was synthesized, and titanium based bottle polyester was synthesized on a 30,000 ton annual industrial plant. At the same time, the characterization and processing properties of titanium based and antimony based polyester were studied. Compared with commercial antimony based polyester, TMPC chips had faster SSP rate and lower AA content, easier crystallization and high catalyst activity, easy to form macromolecular chains, and the rheology of polyester melt also showed a wider processing range. However, the chain end thermal degradation reaction of titanium based bottle chips was slightly larger than that of antimony based bottle chips, and the α transition temperature in DMA test also led to the molecular chain motion of titanium bottle chips is more easily affected by temperature, which was not conducive to maintaining a better viscosity drop and AA value of bottle preform for a long time in the high-temperature injection molding process. To sum up, according to the performance test results, by using TMPC catalyst and adjusting the processing conditions to control the injection molding process of TMPC polyester, titanium bottle preform with better viscosity drop and AA content can be obtained. Finally, the bottle preform with a weight of 28.5g was prepared by using titanium TMPC bottle chips. The injection molding processing temperature was reduced by 10 °C, the viscosity drop was equivalent to that of commercial antimony bottle preform, the end carboxyl group was reduced by 54%, the color index b value was reduced by 17.3%, and the AA content was reduced by 19.8%.

Abstract: Polyphenylene sulfide (PPS) fiber is widely used in the fields of high-temperature filtration, protective clothing, electronics, automobile, and aircrafts sectors relying on its excellent heat and chemical resistance. However, PPS fiber is easily oxidized under high temperature, which vastly restricts its applications. In this study, using the copper nanoparticles loaded halloysite nanotubes (HNTs@Cu) as a nanofiller, we prepared a PPS composite fiber with improved oxidation resistance. The successful loading of copper nanoparticles into HNTs was demonstrated through TEM and elemental analysis. The crystallinity, orientation, thermal and mechanical properties of PPS nanocomposite fibers were investigated via DSC, XRD, WXRD, TGA and mechanical test. While the mechanical performance of the composite fibers was slightly decreased, the thermal stability was improved when comparing to the neat PPS fiber. The composite fiber with 1.0 wt.% loading of HNTs@Cu showed an over 100% retention rate of breaking strength after thermal oxidative aging, suggesting an improvement in oxidation resistance of PPS fiber. This work provides an effective and accessible method for improving the thermal stability and oxidation resistance of PPS fibers, which thereby helps to extend the applications of PPS fibers in high temperature environment.

Abstract: When a pure liquid crystal is dispersed into a suitable polymer to form micron-sized droplet, then it is called Polymer-dispersed liquid crystal (PDLC). In the present study, PDLC of different concentrations were prepared by dispersing a conducting polymer poly (3, 4–ethylenedioxy thiophene): poly (styrene sulfonate) into a cholestryl palmitate. The differential scanning calorimetry and fabry perot scattering studies were employed to study thermal and optical properties. It was found that the phase transition for PDLC occurs at a temperature different than those exhibited by pure liquid crystal. The behaviour of PDLC for parallel and perpendicular electric field has been investigated and the dielectric constant is determined. The value of dielectric constant and conductivity were found to increase with increasing concentration of polymer. The bistability and reflective properties of pure cholesteric liquid crystal can be minimized by dispersing polymer which makes material suitable for high contrast at large viewing angles.

Abstract: Carbonyl iron is an excellent microwave absorption material. However, the high density limits its application in lightweight microwave absorbing. In this study, flake carbonyl iron (FCI) was prepared by high-energy ball milling, and mixed with TPU to prepare the TPU/FCI composites. The large shape anisotropy of FCI makes the TPU/FCI samples exhibit higher permittivity and permeability, and consequently better microwave absorption performance than TPU/SCI (spherical carbonyl iron). Then, rGO was added into the TPU/FCI composites. The permittivity of the TPU/FCI/rGO composites is significantly enhanced by a few amount of rGO (less than 0.5 wt.%). As a result, the TPU/FCI/rGO sample with m_FCI: m_TPU = 3:10 and 0.5 wt.% rGO consumes only half of FCI that the TPU/FCI sample with m_FCI: m_TPU = 6:10 uses, and shows much better microwave absorbing performance than this TPU/FCI sample, that the minimum reflection loss reaches-68.3 dB (at 3.4 mm) and the effective absorption bandwidth is up to 5.9 GHz (at 1.5 mm). The TPU/FCI/rGO materials demonstrate promising application in light-weight high-efficient microwave attenuation.

Abstract: Metal matrix composite materials are a novel material generation capable of handling the implementation of advanced technology's growing needs. Aluminium-based metal matrix composites are widely used in automobiles and aerospace, as well as other industries, including defence and marine systems, due to their relatively low processing costs as compared to other matrices such as magnesium, copper, titanium, and zinc. Ceramic particles were shown to improve mechanical properties like hardness and tensile strength. The product's compactness and price, however, were both boosted. Agricultural waste materials are widely available today in significant amounts, and researchers have focused on using wastes as reinforcing fillers in composites to counteract pollution. Rice husk ash added to an aluminium alloy matrix increases the composite's mechanical properties while also increasing its wear resistance. According to scanning electron micrographs of the composite, the ash from rice husks is evenly distributed all over the aluminium matrix. Wear can vary from micro-cutting to oxidation at high temperatures in an aluminium alloy. Strain fields are produced and composite material wear resistance is improved due to the difference in coefficients of thermal expansion between the matrix and reinforcing materials. This study focuses on the production process, properties, and performance of an aluminium alloy composite incorporating rice husk ash, which has high hardness as well as wear resistance.

Abstract: Transport industry plays a vital role in development of economy of countries. To increase the load carrying capacity of the truck, the weight of truck bed may be reduced using fibre reinforced composite material. In this work, a numerical investigation is performed to reduce the weight of the truck bed using different types of laminated composites. An extensive study is conducted using unidirectional and woven fibres of glass, carbon and Kevlar fibres with polyester, epoxy and vinyl ester resins. Carbon fibre laminated plates have higher stiffness than Glass and Kevlar composite plates. Asymmetrically hybrid composite plates have lower stiffness than symmetrically hybrid composite plates. It is observed that the stiffness of plate is increased when kevlar unidirectional fibres are arranged at top and bottom of the laminate. [K/G_w]_S hybrid composite plates has the lowest deflection than other five hybrid composite plates. An optimization study is performed to identify the influencing parameter for deflection of the composite materials among material type, fibre volumetric fraction and the thickness of plate using Taguchi method. The results revealed that thickness of the plate has more influential than other two parameters.

Abstract: Researchers are envisaging in the replacement of the metal and its alloys with natural materials for its superior availability and inferior cost. Although the natural fibers are available in abundant, the issue is their strength and thermal property which are considerably lower than conventional materials. This inferior property lieu put aside of using it for many applications. In order to overcome that the natural materials are hybridized to obtain the combined properties of individual materials. In the current work, natural fibers like hemp, banana and bamboo fibers were reinforced in epoxy resin and their mechanical and water absorption properties were evaluated. Main application considered now are in external casing for many devices like motors, generators and so on wherein the material should capable to work with the moisture along with mechanical strength. The material is developed specifically for this external application with relevant test like absorption of moisture and mechanical tests. It could be noted from the results that a tensile strength, flexural strength, impact strength and inter-laminar shear strength of 35.51 MPa, 96.99 MPa, 4.86 J and 3.6 MPa respectively has been obtained for sample with 30 % hemp fibers. Alongside, minimum voids and water absorption were obtained for the same composite configuration. These test reveals that these variants could effectively replaces the external metal casing in harsh environment

Abstract: In this work 3,5 Bis(Tri fluro methyl)Benzyl amine phenyl alanine a monmer molecule is DFT theoretically optimized to get the structural insight of the molecule. Band gap energy, Mullikan atomic charges, DOS spectral analysis, HOMO - LUMO, Electrostatic surface potential , molecular electrostatic potential and theoretical Raman spectral analysis is computed and compared with the experimental data .Since this molecule shows self assembly similar to peptide molecules it is quite interesting to analyze its structure based on theory and experimental the results suggests the H –boding interactions between the molecules is the key mechanism. The band energy from DOS plots suggests the molecular interactions through π-π .The possibility of the self assembly is explained further from Raman spectral studies that tells the mode specific interaction among the molecules..