(Fig. 3) shows the tensile properties of the PLA/EVA (80/ 20) blends. The toughness of the PLA was only improved to a certain extent by 20 wt.% EVA0, having an elongation
at break (eb) of 28%. After incorporation of 20 wt.% of EVA copolymer (with VA content between 40 and 70 wt.%), the eb of PLA dramatically increased to more than 300%,
meanwhile the yield strength (ry) dropped in comparison with that of the pure PLA (75 MPa, Table 2). Upon drawing, extensive stress-whitening throughout the specimen was
observed accompanied by neck formation and stable neck growth. The mechanism of this ductile behavior will be discussed later. Since hardly any phase separation was observed
in the PLA/EVA90 (80/20) blend, it exhibits similar tensile behavior to pure PLA, viz. low eb and high ry.