Decomposition behaviour of Kevlar 49 fibres: Part I. AtT≈T d

Abstract

The structural changes which accompany decomposition of Kevlar 49 fibres at T = 500°C and 550°C, respectively, have been elucidated. At both these temperatures, cumulative thermal exposures of specific durations, teem(T), are required to result in decomposition. The conspicuous features which characterize isothermal decomposition of the fibres are: (i) progressive reduction and an eventual total loss in fibre crystallinity, (ii) progressive loss in weight, (iii) introduction of surface damages, (iv) introduction of hollowness, and (v) deterioration in tensile proptrties.

Effect of thermal aging on the crystal structural characteristics of poly(tetra fluoro ethylene)

“…Above 308C, the 15 7 helix exhibits different types of disorders [15,16,21]. Close to 1508C, conformational changes in the 15 7 helix have also been reported [14]. Details of the structural characteristics of various phases, induced by thermal, mechanical, and pressure effects, have been compiled by Biswas and Vijayan [23].…”

“…In the past, the authors have carried out extensive investigations on the effects of thermal aging on some polyamides viz., Kevlar, Twaron, Nylon 6,6, and Nomex. Their studies established that the thermal aging causes significant residual effects on the crystal as well as macrostructural characteristics, tensile properties, weight, etc., of the polyamides [4][5][6][7][8][9][10][11][12][13]. This article reports the details of observations on the residual effects of thermal aging on the crystal structural characteristics of an entirely different type of polymer viz., a fluoro carbon, poly(tetra fluoro ethylene) (PTFE), derived by wide angle X-ray diffraction methods.…”

Hydrothermal Synthesis of Zinc Oxide Nanowires on Kevlar using ALD and Sputtered ZnO Seed Layers

“…This application requires the uniform growth of NWs on novel substrates such as Kevlar. Due to the low decomposition temperature of Kevlar (~ 400 C), potential growth processes are limited to low temperature hydrothermal methods [10,11]. To achieve selective growth of ZnO NWs on Kevlar, we used a uniform coating of ZnO to seed growth [12,13], rather than the more widely used metal catalyst method [14].…”

Assessment of Factors Affecting the Continuing Performance of Firefighters’ Protective Clothing: A Literature Review

“…Such a relationship between mechanical properties and thermal exposure confirms that the level of damage to meta-aramid fibre is a function of both temperature and duration of thermal ageing, which is consistent with the previous results from the X-ray diffraction method and scanning electron microscopy. Iyer et al [17,18] carried out similar research on another common fabric in construction of firefighters' protective clothing, para-aramid. They correlated some features of an X-ray diffraction pattern such as position and half width of reflection peaks and integrated intensity of the diffraction profile, with the temperature and duration of exposure.…”

“…Fire Technology 2011 Iyer et al [17,18] examined the effects of thermal exposures on para-aramid specimens. Specimens of para-aramid were aged in a series of isothermal tests in a furnace using a variety of temperatures from 150°C to 550°C (the fabric's decomposition temperature), for cumulative durations ranging from 0.5 to 7000 h in one to 12 stages.…”