Preparation And Properties Of Polylactic Acid-Based Biomedical Composites

The biological composite material has the performance advantage which the single component material cannot compare,it may concentrate many kinds of component's performance advantages,abandons its respective shortcoming,causes the material to have the comprehensive performance.Poly(lactic acid)has been widely used in the field of biomedicine because of its good biocompatibility and biodegradability.Polylactic acid is recognized as the most promising biomedical material in the new century.The application of PLA in China is not only in environmental protection,but also in the construction of circular economy and economical society.The industrialization of polylactic acid will greatly increase the added value of crops.In this paper,poly(lactic acid)was compounded with starch and hydroxyapatite respectively,and thermoplastic acetylated starch/poly(lactic acid)composite and hydroxyapatite/poly(lactic acid)composite were prepared.The structure and properties of the materials were studied.The following conclusions are drawn:(1)Thermoplastic acetylated starch(TPAS)/polylactic acid(PLA)composites were prepared by melt blending.The mechanical,thermal,DMTA and morphological properties of TPAS/ PLA composites were studied.TPAS was prepared with acetylated starch as matrix and glycerol as plasticizer.The experimental results show that: With the increase of TPAS content,the toughness of TPAS/ PLA composites was significantly improved.When the TPAS content was 40 wt %,the elongation at break increased by more than 4 times.The addition of TPAS had little effect on the thermal stability of the composites.DSC,DMTA and SEM analysis showed that PLA and TPAS were incompatible.The addition of TPAS promoted the crystallization of PLA,the thermal stability of the material is reduced,but the degradation behavior is limited in the process of material processing,which has little influence on the material performance.(2)Using calcium hydroxide and phosphoric acid as raw materials,n-HA was prepared by freeze-drying method.The n-HA is a highly active calcium deficient type with a diameter of about 20 nm and a length of 100-200 nm needle-shaped crystal.g-HA was obtained by ring-opening polymerization of lactide with stannous octanate as catalyst,The basic properties of n-HA have not changed after modification,The degree of crystallization is perfect,And g-HA is less than n-HA in reunion phenomenon.(3)The g-HA /PLA nanocomposites obtained by ultrasonic dispersion and solution mixing method have good dispersion and interfacial bonding effects.G-ha,as a good compatibilizer,plays a good role in improving the dispersion of g-HA in PLA matrix and improving the interfacial bonding strength of nanocomposites.Compared with pure PLA and n-HA/PLA nanocomposites,the bending modulus and energy storage modulus of g-HA /PLA were significantly improved.The vitrification temperature has been increased.It is expected to be used as a scaffold for bone repair and tissue engineering.