40207_06THERMOPLASTIC RESINS - THERMOPLASTIC RESINS Lars...

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THERMOPLASTIC RESINS 4 Lars A. Berglund 6.1 INTRODUCTION posites offer advantages. They have very low toxicity since they do not contain reactive chemicals (therefore storage life is infinite). Because it is possible to remelt and dissolve such thermoplastics, their composites are also easily recycled or combined with other recy- cled materials in the market for molding compounds. In the aerospace market, composites based on toughened epoxies dominate. The poten- tially cheaper manufacturing of thermoplastic extent necessary to motivate large-scale invest- ment in new manufacturing equipment. However, for the next generation of aircraft, interest in thermoplastic composites is high. Higher flying speeds require higher tempera- tures in the materials than the maximum temperature available from epoxy-based com- posites in use today. Since the release of gases during processing and inherent brittleness are serious disadvantages of thermoset polyimides, thermoplastic composites are of great interest. In the automotive market, thermoplastic composites are used extensively. Matched-die compression molding of glass mat thermo- plastics (GMT), primarily based on glass fiber/polypropylene (GF/PP), is common, because it permits fast processing cycles for fairly large components. In the established field of injection molded components, materi- als are used with long fibers (5-10mm) in molding pellets. This leads to improved Thermoplastic composites form a fairly new group of materials. Commercial prepreg tape such as CF/PEEK (carbon fiber/polyether etherketone) and later CF/PPS (polyphenyle- nesulfide) was introduced in the early 1980s. However, as early as 1966, Menges reported on improved static strength and fatigue resistance when epoxy was replaced by polyamide 6 as a composite matrix (Menges, 1966). In the mid fone) due to expectations of better processing methods and improved toughness characteris- tics. However, solvent resistance was found to be a problem. Composites later introduced based on semi-crystalline thermoplastics, such as PEEK and PPS, which have been introduced more recently, have excellent chemical resis- tance and are superior to epoxy-based composites in this respect. Enthusiasm for thermoplastic composites is generated for, basically, three different rea- sons. First, processing can be faster than for thermoset composites since no curing reaction is required. Thermoplastic composites only require heating, shaping and cooling. Secondly, the properties are attractive, in par- ticular, high delamination resistance and damage tolerance, low moisture absorption and the excellent chemical resistance of semi- crystalline polymers. Thirdly, in light of environmental concerns, thermoplastic com- 1970s there was interest in CF/PSU (Po1YSu1- composites has not yet been realized to the mechanical properties compared with materi- als based 0; shorter fibeis (Truckenmueller and Handbook of Composites. Edited by S.T. Peters. Published in 1998 by Chapman &Hall, London. ISBN 0 412 54020 7 1991).
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This note was uploaded on 03/16/2010 for the course MECHANICAL ME765401 taught by Professor Prof.sulis during the Spring '10 term at Institut Teknologi Bandung.

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40207_06THERMOPLASTIC RESINS - THERMOPLASTIC RESINS Lars...

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