The Research Of Bio-based PLA/ENR Dynamic Vulcanization Thermoplastic Elastomer

Thermoplastic vulcanizate(TPV)is gradually replacing traditional vulcanized rubber due to its excellent performance.However,traditional TPVs are usually petroleum-based,which is difficult to be degrade and is dependent on petroleum resources.Therefore,bio-based TPVs have gradually attracted the attention of scholars.In this paper,we used polylactic acid(PLA)and epoxidized natural rubber(ENR)as main raw materials,prepared bio-based PLA/ENR TPVs via dynamic vulcanization,and the effects of processing technic and rubber-plastic ratio on the structure and properties of PLA/ENR TPV were studied.On this basis,we used cellulose nanocrystals(CNC)as a reinforcing material,prepared PLA,ENR,CNC ternary composites by solvent casting method and silane coupling agent modification method,and the the effects of CNC content and silane coupling agent concentration on the structure and properties of composites were studied respectively.1)The research on PLA/ENR processing technology showed that PLA/ENR blend presented bi-continuous structures both before and after dynamic vulcanization,and PLA size increased as processing temperature and time increase.However,after the completion of ENR vulcanization,ENR phase was sheared and torn,some parts became thinner and broken which lead the Vr and processing torque decrease.Additionally,TG results confirmed that some PLA was grafted on ENR network during dynamic vulcanization,and the higher the processing temperature,the more the PLA was grafted.2)The research on rubber-plastic ratio showed that as the ENR content increased,the tensile strength and compression set of TPV decreased,while the elongation at break increased.And the phase morphology changed from "sea-island" structure to bi-continuous structure,and finally to "sea-island" structure.Additionally,thermogravimetric analysis showed that the temperature at which 5% of the PLA/ENR TPV lost weight decreased with increasing ENR content.3)The research on CNC enhanced PLA/ENR TPV showed that solvent casting method and KH-560 modification method can effectively realize the enhancement of PLA/ENR TPV by CNC.When using solvent casting method,as the CNC content increased,the mechanical properties of composits increased first and then decreased,when the content of CNC was 1%,the tensile strength of composites increased by 22%.And the size of PLA decreased first and then increased with the increase of CNC content.In addition,rheological tests showed that with the increase of CNC content,the storage modulus,loss modulus and complex viscosity of the composite increased.When using silane coupling agent modification method,the FT-IR test and elemental analysis proved that KH-560 was successfully grafted onto the surface of CNC,and the higher the concentration of KH-560,the higher the grafting rate.After adding CNC which was modified by 5% KH-560,the tensile strength of composits was increased by 26%,and the storage modulus,loss modulus and complex viscosity of the composites increased.