Influence of tensile deformation on the crystalline organization of ethylene copolymers

The influence of tensile deformation on the crystalline properties of ethylene copolymers (ethylene-vinyl acetate [EVA] copolymers) was investigated by differential scanning calorimetry (DSC). The consequence of drawing on the mobility of the amorphous phase also was investigated through the study of the glass transition temperature. The results indicate that more disorganized crystals, melting at a lower temperature, are present after the tensile deformation, reducing the mobility of the amorphous chains, as shown by an increase of the glass transition temperature. For the lowest molecular weight copolymer, less crystal line changes are observed after the tensile test, probably due to the fact that no stiffening appears during the drawing.