Study On Toughening Modification And Degradation Regulation Of Polylactic Acid By Graphene Oxide

With the development of social economy and the continuous growth of global population,the earth’s resources have been seriously exploited,and the environmental and energy problems such as global warming and depletion of oil resources are becoming more and more serious.As a new environment-friendly polymer material,degradable material polylactic acid is gradually favored by people.Polylactic acid(PLA)fiber,as a new environmental friendly green material fiber that can replace petroleum based fiber,can be completely biodegradable,has good biocompatibility,high crystallinity,high orientation and high strength,good smoothness,dry and breathable,and good luster.However,its mechanical properties are unstable,dyeing temperature sensitive,easy hydrolysis,acid-base resistance,UV degradation and other defects that are not conducive to production need to be improved under continuous research.Therefore,PLA is modified by blending to improve its degradation and thermodynamic properties,but there will be polymer thermodynamic incompatibility.PLA/PCL(polylactic acid / polycaprolactone)composites were prepared by tape casting method,and PGO(graphene oxide grafted polycaprolactone)was selected as the compatibilizer of PLA/PCL system.The effects of the amount of Compatibilizer on the thermodynamic properties and degradation properties of PLA/PCL system were studied.The whole life process of composites is evaluated through life cycle,and the environmental load is analyzed combined with the evaluation results,and the improvement measures are put forward.The mechanical properties of PLA/PCL composite films showed that the addition of PCL increased the elongation at break(increased by 66.1%)and decreased the strength(decreased by 35.7%),while the blends with PGO as compatibilizer increased the elongation at break more(increased by 346.0%)and decreased the strength less(decreased by 20.4%).The data show that PGO has a good compatibilization effect on PLA/PCL blend system,improves the thermal stability of the system,and improves the crystallinity and melting temperature of PLA and PCL.The infrared spectrum and Raman spectrum of PLA/PCL composite film show that the blend system is successfully prepared.It is found that the oxygen-containing group on go does not fully participate in the reaction,while the remaining hydroxyl and epoxy groups can have hydrogen bond and covalent bond with PLA,improve its compatibility and improve the compatibility of the mixture.SEM analysis shows that the PLA/PCL/PGO phase interface is smoother,which further proves that the compatibilization effect of PGO is obvious.The life cycle assessment of the blend composites shows that the synthesis of the two degradable biopolymers has less load on the environment,especially the pollution caused by the waste process can be ignored,while the production of compatibilizer PGO has a greater load on the environment,especially the discharge of organic pollutants such as potassium and the use and waste of acidic solvents have a greater toxicity to marine aquatic ecology.In this subject,go grafted flexible segments were used as compatibilizers to modify the compatibility of PLA and PCL blends.The representativeness of grafted flexible chains remains to be discussed and needs further experiments to improve.In subsequent experiments,we can consider grafting different flexible segments and try the synergy of multiple segments to achieve better results.