Research On The Synthesis Of PLCL And Its Compatibilizing Properties For PCL/PLA Blends

To meet the needs of the sustainable society and solve the global environmental pollution problem,people are paying more and more attention to the development of environmentally friendly sustainable materials.Biodegradable materials that meet the above requirements have attracted more and more attention and have been widely used in packaging,fiber,agriculture,biomedicine and other fields.Poly(L-lactide)(PLA)and Poly(ε-caprolactone)(PCL)have been widely researched because of their good biocompatibility,biodegradability,non-toxicity of degradation products and drug permeability.However,they have defects in mechanical properties:PLA has high strength and poor toughness,and PCL has good toughness but low strength.Poly(L-lactide-co-ε-caprolactone)(PLCL)is a copolymer of lactide and caprolactone.It has good toughness and makes up for the slow degradation rate of PLA.In this study,the amorphous PLCL copolymer was prepared by the ring-opening polymerization method,and the influence of the synthesis process conditions on the structure and property of the PLCL was explored.And then,the PLCL was used as a compatibilizer to resaerch its compatibility and foaming performance of PCL and PLA blend system.The main works are as follows:1、With the amount of catalyst,polymerization time,and feed ratio as variables,the influence of the synthesis process on the composition and properties of PLCL copolymer was researched.The research showed that the content of LA in PLCL copolymer increased first and then decreased with the decrease of the amount of catalyst and the increase of polymerization time,and it increased with the increase of the feed ratio.The number average molecular weight of PLCL copolymer increased first and then decreased with the gradual decreased in the amount of catalyst,the gradual increased in polymerization time and feed ratio.The mechanical properties of PLCL copolymers were affected by the amount of LA and average molecular weight:the higher the amount of LA,the greater the average molecular weight,the higher the elastic modulus and breaking strength of the PLCL copolymer,and the lower the elongation at break.Among them,the elastic modulus of PLCL(1:1-3000:1-30h)was 8.5±0.6 MPa,the breaking strength was 15.1±0.9 MPa,and the breaking elongation was 2661.3±575.9%,showing the best mechanical properties.In addition,compared with commercial PLCL copolymers,it not only had better toughness,elasticity and processability,but also had the same good biocompatibility.2、Select PLCL(1:1-3000:1-30h)to be added to PLA/PCL blends,and research the influence of PLCL on the compatibility of PLA/PCL blends.The research showed that the addition of PLCL made the phase interface of the blends blurred,improved the degree of phase separation,and improved the compatibility of the blends.The addition of PLCL enhanced the interaction between the PCL segment and the PLA segment,which limited the crystallization ability of the two phases to a certain extent,but generally speaking,the crystallinity of the two phases did not change much.The addition of PLCL improved the mechanical properties of the PLA/PCL blends.When the amount of PLCL added was 30%,the breaking strength of the PLA/PCL blends increased by 24%,and the elongation at break increased by 395%.This was because PLCL improved the compatibility of the blends and enhanced its interface bonding force.It could be seen that PLCL could be a compatibilizer,effectively improving the compatibility and mechanical properties of PLA/PCL blends.3、Select PLCL(1:1-3000:1-30h)to be added to PCL/PLA blends,and research the influence of blending components on the foaming behavior of PCL/PLA/PLCL blends.The research showed that the addition of PLCL improves the cell uniformity of the blend and made the cell morphology more uniform.With the increase of PLCL content,the cell size gradually decreased,the cell density gradually increased,and the foaming ratio decreased significantly.This was because as the PLCL content increased,the crystallinity of the PCL phase in the blend gradually increased,providing more nucleation sites,resulting in an increase in the cell density of the foamed sample and a decrease in cell size.In addition,the addition of PLCL significantly improves the compressive strength of the foamed samples of PCL/PLA blends.When the PLCL content is 5%,the compressive strength is the maximum.It could be seen that the PCL/PLA/PLCL blend foam material was expected to be used as a tissue engineering scaffold in the biomedical field.