Study On Toughening Modification Of Poly(Lactic Acid) By Solution Blending Method

Poly(lactic acid)(PLA) is a kind of completely biodegradable and environment-friendly materials, who,s final products are carbon dioxide and water.PLA has good thermal stability, good biocompatibility, high strength, etc, and has excellent plasticity processing performance, which can be widely used in agriculture、 forestry、clothing fields. However, PLA also has many defects, such as big brittle, poor impact resistance, etc. In order to meet the needs of various industries, PLA must be modified, and the most important research question is toughening modification of polylactic acid.At present, domestic and foreign scholars mainly adopt chemical and physical methods for the modification of PLA, and physical method is the common one with simple process operation, high yield and low cost. In this paper, PLA-based blends and PLA-based compsites prepared from flexibility biodegradable plastics and inorganic particles by solution blendingwere studied, and the thermal stability, fracture toughness, mechanical properties and morphology were studied.The research results are as follows:1. The results of synergistic toughening PLA by Polybutylene succinate(PBS) and nano calcium carbonate(Ca CO3): PBS did not affect the thermal stability of PLA, meanwhile Ca CO3 reduced the thermal stability of PLA, and PBS and Ca CO3 simultaneously were added in PLA, the thermal stability of PLA/PBS/Ca CO3 composites was slightly lower compared to pure PLA. Compared with pure PLA, the fracture toughness and bending strength of PLA/PBS blends and PLA/Ca CO3 composites were increased significantly, while PBS and Ca CO3 were simultaneously added to PLA, which further improved the fracture toughness and flexural strength of PLA. PBS reduced the bending modulus of PLA, while PBS and Ca CO3 were simultaneously added to PLA, which improved the flexural modulus of PLA/PBS/Ca CO3 composites. SEM pictures showed that the fracture surfaces of PLA/PBS blends, PLA/Ca CO3 composites and PLA/PBS/Ca CO3 composites were rough compared to pure PLA, and TEM pictures showed that Ca CO3 particles were uniformly dispersed in PLA matrix. Summary, PBS and Ca CO3 have synergistic toughening effects on PLA with having no effects on mechanical properties of PLA.2. The results of synergistic toughening PLA by Polyethylene succinate(PES) and silicon carbide(Si C): the addition of PES and Si C did not affect the thermal stability of PLA. Compared with pure PLA, the fracture toughness and bending strength of PLA/PES blends and PLA/Si C composites were increased, for PLA/PES blends, when Si C was added to them again, which further improved the fracture toughness and flexural strength of PLA. PES reduced the bending modulus of PLA, while PES and Si C were simultaneously added to PLA, which improved the flexural modulus of PLA/PES/Si C composites. SEM images showed that the fracture surfaces of PLA/PBS blends, PLA/Si C composites and PLA/PES/Si C composites were rough compared to pure PLA. TEM images showed that the Si C were evenly dispersed in PLA matrix. PES and Si C have compound toughening effects on PLA with having no effects on mechanical properties of PLA.