DETERMINATION OF THE VINYL-ACETATE CONTENT IN ETHYLENE-VINYL ACETATE COPOLYMERS BY THERMOGRAVIMETRIC ANALYSIS

The dependence of thermal degradation behaviour on vinyl acetate (VA) content of ethylene-vinyl acetate (EVA) copolymers was studied by ther mogravimetric analysis (t.g.a.). Among the parameters investigated, th e maximum rate of weight loss at the stage of acetic acid evolution wa s found to have a linear relationship with VA content and to be indepe ndent of molecular weight and heating rate. Thus, a new method based o n t.g.a. for the prediction of VA content of EVA copolymers is suggest ed.