STRUCTURAL-ANALYSIS OF POLY(ETHYLENE-TEREPHTHALATE) REINFORCED WITH GLASS-FIBER - THERMAL-BEHAVIOR AND CORRELATION BETWEEN PA-FTIR AND DSC MEASUREMENTS

In this article, the correlation between PA-FTIR and DSC techniques wa s carried out to obtain a more comprehensive interpretation for the fi ber-matrix interface of glass fiber-reinforced PET and the dependence on annealing temperature. In contrast to the thermal behavior of an un annealed matrix or an annealed one at low temperatures (below 110 degr ees C), glass transition is barely perceptible and no crystallization peak can be found in the composite. Therefore, the lack of these therm al characteristics indicates the absence of the primary isomerization in the matrix. Similarly to the isolated matrix, low-melting and high- melting peaks appear in the thermograms of the annealed composite beyo nd 135 degrees C, but the size and perfection of crystallites seems to be less in the composite. Conversely to the spectroscopic results, th e crystallinity values of the composite tend only to coincide with tho se of the annealed isolated matrix at temperatures beyond 150 degrees C, and below this temperature, they are always lower, until the primar y isomerization of the matrix. A comparison between the results obtain ed with both techniques seems to indicate an improvement on the fiber- matrix interface in which an interfacial structure with low degree of perfection changes to more perfect crystals due to the annealing treat ment. (C) 1996 John Wiley & Sons, Inc.