Study On Interfacial Compatibility And Crystallization Behavior Of High Performance PLA/PA11 Bio-based Composites Prepared By Reactive Blending

Among many bio-based polymer materials,polylactic acid(PLA)with good biocompatibility has great application potential in the fields of food packaging,biomedicine,tissue engineering,etc.because of its high strength and high modulus.However,due to the shortcomings of poor toughness,slow crystallization rate and poor heat resistance,the application development of PLA is limited.In order to toughen PLA while maintaining its bio-based property,nylon 11(PA11),which is also a bio-based material,was selected as the toughening material of PLA.PA11 not only has high strength and excellent toughness,but also has a fast crystallization rate.The use of PA11toughened PLA can achieve the balance of rigidity and toughness of the materials,and prepare high-performance bio-based materials.Interface compatibility is one of the factors that influence the macroscopic properties of materials.In this paper,through reactive blending method,multifunctional epoxy oligomer(ADR)is used as a compatibilizer to improve the compatibility of PLA and PA11 while achieving the effect of toughening PLA.Under the effect of reactive compatibilization,the interface showed good adhesion,and the mechanical properties of the materials were greatly improved.The elongation at break,tensile strength and impact strength of PLA/PA11/ADR(60/40/0.7)components reached 77.57MPa,454.41%and 9.59kJ/m~2,respectively.The improved interface compatibility also improves the barrier properties of the materials to oxygen and water vapor.Compared with pure PLA,the oxygen and water vapor transmission rates of PLA/PA11/ADR(60/40/0.7)components are reduced by 81.81%and 54.60%,respectively.In order to reduce the limitation of PLA crystallization behavior caused by interfacial compatibilization,the addition of modified nano-silica MS not only promoted PLA crystallization behavior,but also strengthened the strength of the material.Compared with PLA/PA11/ADR(60/40/0.7)components,the tensile strength and impact strength of PLA/PA11/ADR/MS(60/40/0.7/1)composites increased by7.06%and 55.10%,respectively.Through the study of non-isothermal crystallization kinetics and isothermal annealing crystallization behavior of PLA and its composite materials,we deeply understood the relationship between the temperature field and the crystallization behavior of the materials,as well as the crystallinity and the mechanical properties of the materials.The results of non-isothermal crystallization kinetics indicated that the presence of MS accelerates the PLA crystallization rate and decreases the crystallization activation energy;After isothermal annealing,the mechanical strength of the composites increased with the increased of PLA crystallinity.The tensile strength and impact strength of the composite materials increased from 72.44MPa and13.68kJ/m~2 of the unannealed components to 82.35MPa and 15.36kJ/m~2 of PLA/PA11/ADR/MS(60/40/0.7/1)component;As the entanglement degree of the molecular chain segment in the composites was deepened after isothermal crystallization,the storage modulus and glass transition temperature of the materials were positively correlated with the crystallinity of PLA.