Study On The Toughness Improvement Of Green Plastic-poly (lactic Acid)

In this study, poly (lactic acid) (PLA) blends with high toughness was prepared by melt blending and reactive compatibilization technique.The dissertation includes three main parts. The first part concentrates on the toughness improvement of PLA with different amounts of ethene/methyl acrylate/glycidyl methacrylate terpolymer (E-MA-GMA). It was found that the epoxy functional group of E-MA-GMA could react with the end group of PLA, which made PLA partial compatible with E-MA-GMA. When the addition of E-MA-GMA was 10wt%, the failure mode changed from brittle fracture of the neat PLA to ductile fracture of the blend as demonstrated by scanning electron microcopy (SEM). The impact strength and elongation at break of PLA were significantly improved, when the content of E-MA-GMA was 20wt%, the impact strength and elongation at break were increased by 329.7% and 1400%, respectively. DSC analysis indicated that addition of PAPI weakened the crystallization ability of PLA.The second part is about the effect of polyaryl polyisocyanate (PAPI) contents on the compatibility of immiscible PLA/PBAT biodegradable blend. It was found that the hydroxyl/carboxyl end groups of PLA and PBAT reacted with the isocyanate group of PAPI to form copolymer, which was located in the PBAT phase and the phase interface. With the increasing adding of PAPI, the Tg of PLA and PBAT became closer, the size of the dispersed PBAT phase was reduced and more even. By means of mechanical test, with the increasing amount of PAPI, the impact strength of PLA/PBAT/PAPI blends increased significantly, while the tensile modulus of the blends decreased. When adding 5 and 10 phr PAPI, the impact strength of PLA/PBAT/PAPI was increased by 662.7% and 541.0%, respectively. DSC analysis indicated that addition of PAPI weakened the crystallization ability of PLA. Dynamic rheological properties study showed that the addition of PAPI led to the gradual increase in the complex viscosity (η*), storage modulus (G') and loss modulus (G'') of PLA/PBAT/PAPI blends.And then the last part studied the effect of different compatilizers on the compatilization of PLA/PBAT blend by means of mechanical test. The result was that: E/GMA-g-PMMA> E-MA-GMA> E-GMA> E/GMA-g-PSAN > E/GMA-g-PS.