Study Of Preparation And Properties Of Degradable Blend Of PLA/PBAT

As the development of economic and modern society,the standard of people’s life has been greatly facilitated by the high development of polymer materials.However,after decades of development and use of common general-purpose plastics such as polyethylene and polyvinyl chloride,a large number of wastes that are difficult to degrade have accumulated.There has been a significant contradiction between the resulting environmental problems and people’s increasing awareness of environmental protection.With the birth and development of biodegradable synthetic polymer materials,more and more research has been focused on improving the performance of biodegradable polymer materials to meet the requirements of related products and market demands.In this paper,Poly(butylene adipate-co-terephthalate)(PBAT)was introduced to prepare blends for improving toughness of PLA and the structure and properties of each component were studied.(1)The PLA/PBAT ratio was fixed at 75/25,and a two-phase blend was prepared using the co-rotating parallel tri-screw extruder developed by our own research group.The results show that the blends increase the elongation at break from 7%to more than 80%at the cost of losing some of the PLA’s modulus,which significantly improves the toughness of the blends.Its microscopic morphology shows that the strength of the two-phase interface is weak,so improving the two-phase interface will help to further improve the toughness of the blend.(2)The compatibilizer EGMA containing only epoxy functional groups was blended with a fixed ratio of PLA/PBAT,and the effects of different EGMA contents on the structure and properties of the PLA/PBAT blend were studied.Infrared spectroscopy and dynamic rheological analysis showed that EGMA chemically reacted in the blend and produced PLA-EGMA-PBAT macromolecular structure,which resulted in an increase in storage modulus and loss modulus in the low frequency region;DSC analysis showed that such macromolecular structure reduced the crystallinity of PLA by hindering the movement of the PLA segment;the microscopic morphology shows that the size of the dispersed phase of PBAT is significantly reduced,and the bonding strength between the PLA and PBAT interface is significantly improved;comprehensive mechanical properties show that the use of 10 pph EGMA can still make the blend maintains a tensile strength of approximately 37 MPa,while the elongation at break reaches approximately 440%,and the notch impact strength reaches approximately 39 kJ/m2.(3)In order to compare the effects of different compatibilizers,ternary blends with different compatibilizers amounts were prepared using compatibilizer KT915 containing only maleic anhydride groups and a new compatibilizer KT20 containing the two reactive functional groups mentioned above,respectively.The results show that the reactive functional groups can make the compatibilizer molecules and PLA or PBAT produce copolymers,thereby improving the strength of the phase interface and greatly improving the toughness of the blend.Different compatibilizers have different effects on the size of the PBAT dispersed phase of the blends.The viscoelastic behavior of the blends also differs due to the different compatibilizers.In addition,the mechanism of the difference in toughening effect of different compatibilizers at low and high dosages was also analyzed.(4)In order to verify the toughening effect after filling with degradable materials,two thermoplastic starches were prepared with different compounding plasticizers.And structures and performance of the blends filled with different thermoplastic starches,using different contents of EGMA and different thermoplastic starch mass fractions were studied.The results show that after adding 10wt%of thermoplastic starch(G-TPS,plasticized by glycerin and water)to PLA/PBAT(Matrix),the blend maintains 30%elongation at break and 6.6 kJ/m2 notch impact strength,the blend maintains about 15%elongation at break and 6.2 kJ/m2 notched impact strength after adding another thermoplastic starch(X-TPS,plasticized by glycerin,xylitol and water)10wt%.