Improvement of dynamic tensile properties of Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) polymer alloys using a crosslinking agent and observation of fracture surfaces

• When, in the mixing ratio of PLA/PBAT, the PBAT value was larger, the crosslinking agent increased the elongation at break.
• The measured maximum stresses were close to the Voigt model or the Halpin-Tsai model.
• When PLA/PBAT = 50/50 and 30/70, the fracture had occurred along an interface between the PLA-rich and the PBAT-rich regions.

Stress-strain curves of poly(lactic acid)/Poly(butylene adipate-co-terephthalate) polymer alloys (80/20, 70/30, 60/40, 50/50, 30/70) were measured using the tensile split Hopkinson bar method. The effects of mixing ratio and crosslinking agent addition on Young's modulus, maximum stress, elongation at break and dissipated work were examined. The crosslinking agent addition significantly increased elongation at break when the mixing ratio was 50/50 and 30/70. The results were compared with the results of Izod impact tests which measure the fracture toughness of materials. The tensile behavior of specimens during dynamic tensile tests was observed using a high speed video camera. The deformation of the gage area was major. The results of Young's modulus, maximum stress, and elongation at break were compared with the mixture laws of composite materials. The fracture mechanism of the specimens was discussed using observation of the fracture surfaces of the tensile test specimens. When the crosslinking agent was not used, it seemed that the fracture occurred along an interface between the PLA-rich region and the PBAT-rich region.