Papers by Keyword: Thermoplastic

Abstract: Nowadays, orthoses are made from fibre reinforced thermoset based composites with a high manual labor input. These thermoset based orthoses are no longer formable, which brings forth a significant disadvantage. Hence, hybrid laminates consisting of fibre reinforced thermoplastic films and thin metal sheets can replace successive thermoset based systems due to their advantages of higher formability and the suitability for mass production. In the present work, various surface treatment methods like pickling or mechanical blasting have been used on thin metal sheets to increase the adhesive and shear strength of the produced thermoplastic based hybrid laminates. The modified metal sheets were further combined with basalt fibre reinforced interlayers to manufacture overlap samples, which were used to determine the tensile shear strength. In addition, the roughness of the modified metal sheets has also been investigated. Moreover, the consolidation parameters such as pressure, holding time and temperature have been varied for the production of hybrid laminates using hot-pressing process and then the microstructural images have been recorded. Finally, the mechanical properties of the produced hybrid laminates have been tested by means of a three-point bending test and the interlaminar shear strength has been analyzed.

Abstract: Increasing waste streams of carbon fibers (CF) and carbon fiber reinforced plastics (CFRP) lead to increasing need for recycling and to growing amounts of recycled carbon fibers. A main issue in current research for carbon fiber recycling is the reuse of regained fibers. Carbon staple fibers such as recycled fibers hold big potential for mechanical properties of lightweight parts, if used properly. Applying recycled CF (rCF) as milled reinforcement fibers or as nonwoven in carbon fiber reinforced plastic leads to a poor yield of mechanical proper due to low fiber orientation, limitations in fiber volume content or due to short fiber length. The rC staple fiber tape presents a more efficient approach. Recycled carbon fibers are blended with 50 wt. % thermoplastic nylon 6 fibers and processed through a roller card to a sliver, which is a linear fibrous intermediate. The sliver is continuously drawn, formed, heated and consolidated to the thermoplastic rC staple fiber tape. The tape is similar to common carbon fiber tapes or to continuous tows but has different positive properties, such as high fiber orientation, homogeneous blend of fiber and matrix and suitability for deep drawing.

Abstract: In the last decades the studies on thermoplastic composites reinforced with natural fibres have been mostly focused on vegetable lignocellulosic or cellulosic fibres. These materials provide eco-sustainable solutions for a large range of applications and have been actually adopted by multiple industries. The interest on fibres of animal origin is more recent and research on composites reinforced with these fibres predominantly composed of keratin, such as wool, feathers or silk, is increasing in virtue of some advantageous properties that may overcome some of the intrinsic limitations from vegetable fibres. The combined use of vegetable and animal fibres in composites appropriate for melt blending processing is at early stages of research. After chemical treatments, the fibres of animal origin have been mostly applied as binders between vegetable fibres and polymers, not as main constituents of these composites. The use of both types of fibres simultaneously in composites of thermoplastic matrices is the subject of the present study wherein the fibres of animal origin (wool) are different kinds of residues from a textile industry and the fibres of vegetable origin (wood) are residues from carpentry activities. The chemical composition, the macro and microstructure of the fibres is analyzed, as well as that of composites that combine non-biodegradable and biodegradable polymers with diverse ratios of fibres in different conditions (wool as cards, yarns and felt cloths; wood as sawdust). The addition of coupling agents to enhance the compatibility between wool, wood and different polymers is also analysed.

Abstract: The article is devoted to the research into the utilization of large volume industrial wastes to produce mineral-polymer composite construction materials. To produce the composites, polyvinyl chloride wastes have been suggested as binding thermoplastic matrix and ash-and-slag wastes, which are the by-product of coal combustion at TPP of Irkutsk Oblast, as mineral filler. Since the problem of accumulation and storage, such as large volumes of power generation industry wastes is becoming more and more serious, the recycling of these wastes with the production of useful products is the vital task. Plants that manufacture products from PVC also produce plastic wastes in the form of rejected and substandard raw material, which can be recycled. At the same time, the problem of production available construction materials for the Baikal region from the local cheap raw material is solved. The team of Irkutsk National Research Technical University has conducted a number of the industrial trials on the production of mineral-polymer composites by the method of extrusion. As a result, the principal opportunity of co-utilization of PVC wastes and ash-and-slag materials during the production of composite construction materials has been testified. Local construction companies can use the produced materials.

Abstract: Industrialisation and the development of manufacturing process nowadays demand a more efficient and environmental friendly production. Microwave energy can be seen as the alternative heating application to meet the demands due to its ability to heat materials volumetrically. In this study, the usage of microwave energy to join thermoplastic is investigated. One of the key features of thermoplastic is the ability to shape when heated to their glass transition temperature and return to the moulded shape when it is cooled. Engineering thermoplastic Acrylonitrile-butadiene-styrene (ABS) was used as member while charcoal powder was used as susceptor material. The joining process was carried out with timing varying from 3 to 5 minutes, adhesive method and direct heating method. Upon the completion of joining, tensile test, 3 points test, hardness test and charpy impact test were conducted and compared to determine the strength of the joint.

Abstract: A novel procedure for installation of PZT sensors on composites is developed. The procedure is shown, through extensive tests, to be reliable, repeatable and repairable. The integrity of the bonded sensors are assessed following the RTCA DO-160 Environmental conditions and test procedures for airborne equipment. The developed bonding film has been tested on both thermoset and thermoplastic coupons and compared co-cured and secondary bonded sensors with epoxy.

Abstract: This paper deals with a new fabrication technique of carbon fiber-reinforced thermoplastic (CFRTP) honeycomb cores and all-CFRTP honeycomb sandwich panels. The CFRTP core was made of plane woven carbon fiber-reinforced polypropylene prepreg sheets. The stacked CFRTP prepreg sheets were periodically hot-pressed at the node locations, and then expanded to form an all-CFRP honeycomb core. The resultant CFRTP honeycomb cores were glued with the same polypropylene-based plain-woven CFRTP skin plates. The mechanical performance of the all-CFRTP honeycomb sandwich panels was evaluated by flexural tests. The experimental results showed the effectiveness of proposed all-CFRTP sandwich panels.

Abstract: The polymer blend was prepared from natural rubber (NR) and polyethylene (PE) powder blended with epoxidized natural rubber (ENR) by using an internal mixer. In this study, epoxidized natural rubber (ENR) was used as compatibilizer for the blends. Blending ENR with PE powder and NR were prepared at various compositions from 0-20% by weight. Then, specimens from the blends were produced by compression molding at 150 °C. The mechanical and morphological properties of the composites were investigated. It was found that the addition of ENR content has improved the tensile strength, compression set and hardness for the ternary compositions composed of NR/PE powder/ENR compared to the binary one (i.e. NR/PE powder). ENR contributed to a better dispersion between the NR and PE phases as observed in the scanning electron microscopy.

Abstract: The development of bio-composites as biodegradable and renewable materials for sustainable technology are advantageous in creating a green and healthy environment. However, the application of natural fiber as a bio-composite material have been found to be restricted especially as it has lower thermal resistance in comparison to synthetic fiber. Therefore, the objective of this study is to investigate the influence of fiber orientations on the tensile properties at various tensile temperatures for unidirectional kenaf polypropylene (PP) composite. Samples were prepared by hot pressing process. In this study, kenaf long fibers that are produced from water retting process is use as a reinforcement agent while PP as a polymer in the composite fabrication. A tensile test was carried out at different temperatures (30°C, 60°C, 90°C, 120°C) for various orientations (0°, 45° and 90°). It was found that an increase of temperature will reduce the modulus and tensile strength where the highest reduction occurred between 60°C to 120°C and most significantly on the orientation of 45° and 90°, which is lower than pure PP. This concludes that the application of kenaf PP composite is optimum between room temperature with a cut-off temperature at 60°C.

Abstract: The incorporation of unmodified halloysite nanotube (HNT) in a thermoplastic sago starch (TPSS) film to form a nanocomposite material was investigated. The TPSS/HNT nanocomposite was fabricated through solvent casting method at varying HNT loading of 0, 0.25, 0.5, 1.0, 3.0, and 5.0 wt.%. Evaluation on mechanical and physical properties (tensile test, water absorption, thickness and density) was made to study the effect of HNT loading on the TPSS properties. Tensile strength achieved an optimum value at 0.25 wt.% of HNT loading and decreased with higher addition of HNT. Meanwhile higher amount of HNT in the nanocomposite film exhibited brittleness with the reduced tensile strain. Water absorption decreased with the addition of HNT due to the difficulty of water molecules to pass through the tortuous path of HNT structure. Thickness and density of the nanocomposite film, however, increased at higher HNT contents. FESEM (field emission scanning electron microscope) which examined the surface morphology of the TPSS/HNT nanocomposite displayed uniformly dispersed HNT in the plasticized starch matrix.