The Study On The Preparation And Properties Of Shape Memory Composites Based On Eucommia Rubber

Shape memory polymers(SMP)are smart materials which could memorize one or more predetermined shape and recover from a temporary shape to a permanent shape after applying an external stimulus such as heat,electricity,magnetism,light,humidity or chemical stimulation and so on.SMPs have great potential application in biomedical material,aviation and space,automobile,textile and self-healings fields due to its large reversible deformation,low density,easy processing,large adjust range of properties,controllable recovery behavior and low lost.This is strategically significant for develop new type of composites based on Eucommia rubber,which could be used as one of the most typical shape memory polymers.We prepared a series of thermotropic shape memory composites with Eucommia rubber as matrix and studied the relation between internal structures,component and mechanical and shape memory properties.The main contents of this manuscript are as follows:Firstly,we studied the effect of mooney viscosity on mechanical property and shape memory properties of Eucommia rubber.The results showed that Eucommia rubber with high mooney viscosity had larger scorch time,vulcanization time,maximum torque MH and minimum torque ML than that with low mooney viscosity,which indicated that Eucommia vulcanized rubber with high mooney viscosity had better processing safety and longer curing time than that with low mooney viscosity.The tear strength,100% modulus and elongation at break had similar trends in Eucommia vulcanized rubber with different mooney viscosity.However,the tensile strength showed an opposite trend in different mooney viscosity of vulcanizations with the increase of sulfur content.There were also similar trends in DSC curves,in which crystallinity of low mooney materials was higher than that of high mooney viscosity in the view of crystalline and melting enthalpy.Shape recovery rate of the high Mooney viscosity Eucommia rubber was up to 98.9%,meanwhile shape recovery rate of the low mooney viscosity Eucommia rubber was up to 81.4% in shape memory properties.Secondly,we studied the effect of the type and amount of filler on the physical and mechanical properties and shape memory properties of Eucommia composites,and observed the one-way and two-way shape memory behavior of Eucommia composites.The results showed that the addition of chitin could improve the modulus of composites,but the tensile strength,tear strength,elongation at break and shape recovery rate were reduced with the increase of chitin.The mechanical and shape memory properties of Eucommia composites were improved obviously with appropriate addition of SiC or CB filler.The recovery rate of the composites was 95.6% with addition of SiC filler(10phr),and the recovery rate was 90.4% with addition of CB filler(5phr).Finally,the composites of Eucommia rubber(TPI)and polybutylene succinate(PBS)were prepared by physical blending method.We studied the effect of blending ratio and the addition of compatilizer on mechanical and shape memory properties in composites.The results showed that the mechanical properties,thermal stimulation temperature decreased gradually with the change of blend ratio.Meanwhile the shape fixity of composites first increased and then decreased along with the increase of dosage of PBS.The shape recovery rate was up to 92.5% when blend ratio of TPI/PBS was 80/20.We also studied the effect of vulcanizer types including S,DCP,S /DCP on properties of shape memory composites.The results showed that the mechanical properties of the materials gradually decreased with the increase of curing agent.The tensile strength,tear strength,and modulus of the S/DCP vulcanized system were better obviously than the other two systems.The properties of tensile strength increased 1-2 MPa,tear strength increased 1-4 KN/m,and 100% modulus rose about 1-3 MPa yet.From the view of shape memory properties,the composites performed excellent shape memory properties when S was 1.6 phr in the sulfur curing system,when DCP was 1.2 phr in the DCP curing system and while DCP was 0.4 phr in the S/DCP curing system.