Research On Preparation And Properties Of Thermo/Electro-Response Shape Memory Composites Based On TPI

Shape memory polymers?SMPs?have the advantages of easy processability,tailor-able transition temperature,low cost,shape deformability.SMPs have found broad application in electronic-electrical,aeronautical-space and medical fields.The application of traditional thermo-response SMPs is restricted because the uncontrolled heat and single responsive way.Electro-response SMPs composites can regulate its shape memory effect by electric field,which have the advantages of precise and well controllable ability.Therefore,it has attracted the attention of researchers.Foam materials have rich cell structures,which can achieve the light weight property and regulate the thermal conductivity and electrical conductivity by various cell structures.Trans-1,4-polyisoprene?TPI?is attracted around the investigators by the large recovery stress and ratio.However,TPI is a thermo-response SMPs,therefore,the fabrication and investigation of TPI-based electro-response shape memory composites and foam composites have important research meaning for broaden the application and TPI's potential.This study uses TPI as based polymer,sulfur as crosslinking agent,single wall carbon nanotube?SWCNT?as electrical nanofiller,microsphere foam agent as foam agent to fabricate TPI shape memory material,electro-response shape memory composites and shape memory foam composites.The relation between structure and property of different material systems have been conducted and the main results were included as follows:1?The influence of sulfur content on properties of TPI was researched.The thermo-response temperature of TPI was decreased from 57.0 ^oC to 37.0 ^oC with sulfur content increased from 0 phr to 2 phr.The main reason was that the movable ability of TPI chain was restricted by crosslink network,which makes the crystal form of TPI changed from mixed?,?form to single?form.The higher crosslinking degree could decrease the fixing ratio of TPI,and eventually the best content of sulfur to get the optimum TPI shape memory material is 0.5 phr to 1.5 phr.2?The influence of SWCNT content on various properties of TPI/SWCNT shape memory composites was considered.In comparison to pure TPI,the electrical conductivity of composites was increased to 8.4 S·m^-1 with 2.5 wt%SWCNT due to the higher electrical conductivity and larger length-diameter ratio of SWCNT.The XRD and DSC results showed that SWCNT leads TPI preferred to generate?crystal form,which increases the melting temperature and crystal temperature of composites.Moreover,TPI/SWCNT composites have the electro-response shape memory property,and TPI/SWCNT composites with 2.5 wt%SWCNT could achieve shape memory recovery effect and have the recovery ratio of 87.5%under 30 V DC.3?The relation between microsphere foam agent content and properties of SWCNT/TPI microsphere foam nanocomposites was researched.Cell-structure could largely decrease the thermal conductivity of foam composites.In comparison to the0.245 W·m^-1·K^-1 in DU-0,DU-9 has the lower thermal conductivity of 0.060 W·m^-1·K^-1.Little microsphere foam agent could enhance the electrical conductivity of foam composites and the electrical conductivity of DU-1 was increased 30%compared to DU-0;but excess microsphere foam agent could largely decrease the electrical conductivity of foam composites and the electrical conductivity of DU-9 was decreased81%compared to DU-0.Moreover,microsphere foam agent could control the electro-response property of foam composites,such as the electro-response recovery ratio of DU-1 reached 93%;but the electro-response recovery of DU-9 was only 20%.