Improvement of Fracture Properies of PLA/PCL Polymer Blends by Control of Phase Structures

Abstract

The blends of poly (lactic acid) (PLA) and poly (ε-caprolactone) (PCL) were prepared by melt blending using lysine triisocyanate (LTI) as a compatibilizer to improve blend miscibility. Critical J-integral at crack initiation, J_in, was measured as a fracture energy parameter, and crystallinity, x_{c, PLA}, and molecular weight, M_w, were evaluated by DSC and GPC, respectively. J_in and M_w tend to increase, while x_{c, PLA} decreases, as the LTI content increase. Increased M_w and reduced x_{c, PLA} are both considered to be due to crosslinking reaction of added LTI. It is also found that the decreased size of spherical PCL phase results in the improvement of J_in indicating that the size change of dispersed PCL phase due to LTI addition plays an important role in determining J_in value.