Preparation And Study On Crystallization Properties Of A Polyesteramide Based On Poly(L-lactic Acid)

Polylactic acid(PLA)is a kind of biodegradable material which is obtained from renewable resources.It's attracted widely attention because of good biocompatibility and excellent comprehensive performance.However,limitations of the PLA application are brittleness and low thermal stability.In order to improve to improve its properties,the copolymerization modification method have been conducted.Therefore,this paper studied the preparation of a kind of polyesteramide with polycaprolactam and PLA.The polycaprolactom chain with hydrogen bonding and excellent thermal stability properties is indroducted to the chain of PLA.The hydrogen bonding bonding interaction as a kind of driving force to improve the crystallization properties of PLA by the rearrangement of molecular chain.PLA has a great potential application in the field of packing.In this paper,different polymerization systems were used to prepared the polyesteramide.Influences of the catalyst dosage,the polymerization time and polymerization temperature on viscosity molecular weight for polyesteramide were discussed.The structure of polyesteramides were analysed by infrared(FT-IR)spectrum and nuclear magnetic resonance(1H-NMR).The thermal,crystallization and rheological properties of the polyesteramide were investigated by And the results showed that the polyesteramide can successfully polymerize by differential scanning calorimeter(DSC),thermo gravimetric(TG),polarizing microscope(POM),X-ray diffraction(XRD)and rotational rhemoter.The results showed that the copolymerization system based on PLA prepolymer and poly caprolactam prepolymer were more easily to prepare polyesteramide.The introduction of polycaprolactam chain improved thermal stability of PLA,accelerated the crystallization of PLA,reduced storage modulus of PLA and increased loss modulus of PLA.At the same time,in order to study the polycaprolactam chain effected on the crystallization properties of PLA,the isothermal and nonisothermal process of polyesteramide were tested by DSC and the crystallization kinetic was analyzed by different theories and methods.The analysis results showed that the Avrami equation can be used to analyze isothermal crystallization kinetics of the polyesteramide.And Mo and Jeziorny method were ideal but Ozawa method was not ideal for dealing with the nonisothermal crystallization process.The values of n were between 2.5 to 3.4,which indicated that crystal shape of polyesteramide was spherulite.The values of crystallization activation energy reflected that the high temperature was beneficial to the isothermal crystallization process of the polyesteramide.The increasing of the PA6 content was helpful to the crystallization of polyesteramide and the increasing of the cooling rate is helpful to improve the rate of crystallization.