Melt Spinning Properties Of Poly(4-hydroxybutyrate) And Preparation Of Modified PBAT Composite Fully Degradable Materials

Poly(4-hydroxybutyrate)(P4HB)is a new biodegradable plastic material,which has good mechanical properties,crystallization properties,wide processing temperature and good biocompatibility.P4 HB is mainly synthesized by biological fermentation.However,due to the complex process of biological fermentation,its production cost is very high.At the same time,because the product is difficult to purify,it is difficult to obtain products with stable quality.The chemical synthesis of polymeric poly(4-hydroxybutyrate)was achieved by using the binary catalytic system developed by our team.The performance of chemical synthesis P4 HB fusion spinning can also be compared with that of biological fermentation.With the excellent performance of P4 HB,it is of high research value and economic value to develop,research and broaden the application field of P4 HB extensively.PBAT itself has shortcomings such as low strength and poor stiffness.In this paper,P4 HB was selected to enhance the modification of PBAT and prepare full biodegradable composites.The research content mainly includes:(1)P4HB absorbable monofilament suture with high orientation and mechanical properties was prepared by melt spinning process.The effects of primary drawing multiple,secondary drawing temperature,secondary drawing multiple and annealing time on spinnability,mechanical properties,crystallization and orientation,surface morphology and degradation properties of P4 HB monofilaments were systematically studied.Finally,it was found that the best monofilament sutures with comprehensive performance could be prepared by choosing 5 times the primary stretching ratio,1.3 times the secondary stretching ratio and 40 ℃ the secondary stretching temperature.The performance of different specifications of P4 HB sutures prepared by the optimized process is higher than that of industry standards and existing absorbable surgical sutures,so P4 HB sutures have broad market prospects.(2)The cross-linking agent BIBP and the cross-linking agent TAIC are added into the PBAT/P4 HB composite material to enhance the capacity of the cross-linking reaction.The gel content of the composite is increasing as the content of BIBP and TAIC is increasing.The gel content of the composite reaches 51.4% when the content of BIBP and TAIC is 0.5% of the blend system.With the increasing of gel content,the tensile properties of the material are obviously improved.SEM and DMA tests showed that the compatibility of blends was gradually improved after the addition of crosslinking agent and crosslinking aid.Thermal analysis showed that the crystallinity of PBAT and P4 HB decreased to a certain extent due to the increased capacity of crosslinking reaction.Rheological tests show that the melt strength and viscosity of the composite are greatly improved compared with PBAT.(3)P4Hb-G-GMA was prepared by fusion grafting method as compatibilizer to enhance the capacity of PBAT/P4 HB system,and the effects of different graft copolymer contents on the structure and properties of PBAT/P4 HB composites were studied.The results showed that the yield strength of PBAT/P4 HB composites was effectively improved with the increase of the content of the compatibilist P4Hb-gGm A,and the tensile strength and toughness of the composites were also improved.The compatibility between PBAT and P4 HB was effectively improved by SEM analysis of compatibilist P4Hb-G-GMA.Thermal analysis showed that the addition of compatibilizer P4Hb-G-GMa could promote the crystallization degree of P4 HB and PBAT phases in the system.The rheological test shows that the melt strength and viscosity of the composites are greatly increased by adding the compatibilizer P4HB-g-GMA,and the melt strength and viscosity are in direct proportion to the content of the compatibilizer.