A study was conducted on the effects of cooling conditions on flexural properties of aramid fiber knitted fabric (AFKF) and glass fiber knitted fabric (GFKF) reinforced thermoplastic polypropylene ...composites. To study these effects, composite laminates were fabricated under a molding pressure of 3MPa for 20min, then consolidated from the melt at different cooling conditions: rapid cooling i.e., quasi-quenching and gradual cooling. Flexural tests were carried out on specimens in two directions: wale and course. Evaluation on thermal properties and morphology was studied using a differential scanning calorimetry (DSC). Flexural properties were little sensitive to the cooling rates; however, gradually cooled specimens showed higher level of crystallinity than rapidly cooled specimens. Furthermore, flexural strengths displayed higher in the wale than in the course directions. SEM micrographs of fracture surfaces revealed poor adhesion between the fiber and polypropylene matrix.
Combinations of inorganic fibers and organic matrices can produce high performance composites such as CFRP and GFRP. Normally, the adhesion between these two material types is not good due to their ...Completely different nature. Composites that consist of a matrix reinforced with fibers of the same material however, may have excellent interfacial strength. Often, the melting temperature of thermoplastic fibers is higher than that of the corresponding bulk material due to molecular orientation in the fibers. Therefore, a processing window between the two melting temperatures of the fibers and the bulk materials may enable fabrication of composites with a high strength interface and fiber reinforcement. We call this class of composites “Interface-less Composites”. In this paper, UHMWPE fibers and PE film were selected as the first step in the validation of this concept. Knitted PE fabric with good drapeability was also used as a reinforcement. The effects of processing temperature and time in film stacking method on mechanical properties were investigated. Even at a low fiber volume fraction (12%) PE/PE composites showed two times higher tensile strength than the neat PE matrix. On the other hand, the tensile strength of PE/Epoxy composites was lower than that of Epoxy resin. This concept can be extended to any thermoplastic material. The use of these composites could greatly improve the recycle ability since matrix and reinforcement are the same materials.
In order to fabricate thick composite laminates, the large number of stacking process is generally required. The thickness was easily increased by placing knitted fabric with bulky characteristic. ...Textile hybrid composite consisting of woven fabric, knitted fabric and braided fabric can be a new concept of textile composites. In this paper, the impact property of textile hybrid composites was investigated. Two woven fabrics were placed at outer layer, and one or two knitted fabric was placed at core layer, in textile hybrid composite. The energy for failure propagation in textile hybrid composite was higher, while in elastic energy calculated from elastic recovery was lower. The absorbed impact energy was higher compared with strain energy obtained from static bending test.
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