Polyethylene terephthalamide

Plastics show T i as low as 2°C for polyisobutylene and as high as 455°C in polyethylene terephthalamide. ASTM methods D2117 and D3418 describe methods for measuring the melt temperature. 

High performance polymer fibers (HPPF) have excellent mechanical properties compared to traditional textile fibers such as nylon. The typical HPPFs are aramid and polyethylene fibers (6). Aramid is a generic name for a class of aromatic polyamide fibers, most of which are varieties of poly(p-pheny-lene terephthalamide). Kevlar is the trade name of the varieties of aramid polymers introduced conunercially by Dupont. The molecules in the fibers of these materials are oriented in the axial direction. Poly(p-phenylene terephthalamide) is a rigid molecule with the following structure ... 

Kuhn model, Equation (1.1). Data for several polymers in addition to polyethylene are given, including a rigid-rod aromatic nylon polymer, poly(p-phenylene terephthalamide) (Kevlar ), as well as the aliphatic nylon polymer poly(hexamethylene adipamide) (nylon-6,6). 

There have been no similar attempts to determine comprehensive sets of elastic constants for oriented fibres or monofilaments. Kawabata [21] devised an apparatus that used a linear differential transformer to measure diametral changes of 0.05 iim in single fibres of diameter 5 fxm subjected to transverse compression. Equation (7.2) above was then used to calculate the transverse modulus El = l/ ii. Results were obtained for poly(p-phenylene terephthalamide) (Kevlar) and high-modulus polyethylene (Tekmilon) fibres. Values of E were in the range 2.31 -2.59 GPa for Kevlar and a value of 1 -2 GPa was found for Tekmilon. 

Major developments in fibre technology have led to ultra-high modulus fibres such as poly-paraphenylene terephthalamide (PPTA) (Kevlar and Twaron) and polyethylene (Dyneema,... 

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