Effect of poly(acrylic acid)‐g‐PCL microstructure on the mechanical properties of starch/PCL blend compatibilized with poly(acrylic acid)‐g‐PCL

Poly(acrylic acid)‐g‐polycaprolactone (PAA‐g‐PCL) graft copolymer was synthesized and starch/PCL blends compatibilized with PAA‐g‐PCL were prepared. The mechanical properties of the starch/PCL blends compatibilized with various PAA‐g‐PCLs that have different graft degrees and graft lengths were investigated. As the graft degree of the PAA‐g‐PCLs that have the same graft length increased, the modulus and the strength of the blends decreased. However, the elongation at break and the tensile toughness of the blends showed a maximum at a certain graft degree (10.8 mol%) owing to the better compatibilizing effect compared to the low (3.9 mol%) and the high (23.4 mol%) graft degree of PAA‐g‐PCL. It was also found that the modulus and the strength of the blends increased with the increase of graft length of the PAA‐g‐PCLs that have the same graft degree (∼11 mol%). However, the blend compatibilized with the short graft length (M.W. of PCL graft: 530) exhibited the highest value of the elongation at break and the tensile toughness. This result is attributed to the self‐crystallization of PAA‐g‐PCL in the blend that has longer PCL grafts.