抄録
In the previous paper, it was pointed out that in some EVA (Ethylene-vinyl alcohol copolymers) specimen, especially 36.6 mole % vinyl alcohol EVA had a higher ethylene content in the crystalline region rather than that of over-all region.
In this paper, in order to clear the relationship between the mechanical properties and the microstructures of EVA, the stress-strain and stress-relaxation behaviour and the dynamic mechanical properties were studied.
The following results were obtained: (1) The glass transition temperature and the loss modulus (E″) main peak's temperature of EVA sample which contained 36.6 mole % VA, were higher than those assumed from the copolymer's given composition. (2) The apparent activation energy of mechanical relaxation of the sample mentioned in (1) was 10_??_20 kcal/mole higher than that observed in other copolymers having almost the same over-all copolymer composition. (3) The VA component in the amorphous region and the crystal perfectness affected to the modulus in the leather region.
From these results, it may be conclude that even if the over-all copolymer composition of EVA samples are almost same, their mechanical properties are different from each other because of the difference in the VA content and the microstructure of both crystalline and amorphous regions.
