Preparation And Characterization Of Shape Memory Materials Based On Recycled PVB

Shape memory polymers（SMPs）,as a kind of smart materials,have been widely used in intelligent textile,aerospace,biomedicine and other fields.With the development and preparation of a variety of SMPs and in-depth theoretical research,it has become a trend to search for cheap materials to prepare SMPs.Polyvinyl butyral（PVB）is mainly used to make intermediate film of automobile safety glass.A large number of Recycled PVB（RPVB）are produced every year with the rapid development of automobile industry.These RPVB still have excellent mechanical properties and processing characteristics,combined with its own high elasticity,which has great potential to prepare SMPs.In this paper,RPVB/styrene maleic anhydride copolymer（SMA）/NH₂-functionalized reduced graphene oxide（NRGO）thermo-and photo-responsive SMPs,RPVB/polyvinyl chloride（PVC）triple SMPs and reconfigurable SMPs were prepared using RPVB as matrix respectively.The effects of the ratio of raw materials on the shape memory properties of blends were investigated,and various shape memory mechanisms were explained from the aspects of gel content,morphology and thermal transition temperature.The main research contents and results are as follows:（1）RPVB/SMA binary blends with different proportions were prepared by melting blending method.The hydroxyl group of RPVB molecule chain and maleic anhydride of SMA molecule chain were crosslinked during melting blending,which provides the structural basis for the shape memory properties of the blends.In tensile shape memory test,the shape fixation ratio（R_f）of the blends increased with the increasement of SMA contents.Shape recovery ratio（R_r）showed a correlation with gel content.The higher the gel content is,the higher R_rof the blends is.When the ratio of RPVB to SMA is 3:1,its R_fand R_rare 97.2%and 99.4%,respectively.（2）The mass ratio of RPVB to SMA was fixed at 3:1,and NRGO was added to prepare ternary blends by melting.The introduction of NRGO endows the blends with excellent photothermal response and does not affect their shape memory performance.The R_fand R_rof the ternary blends with 0.5 phr NRGO are 98.7%and99.9%,respectively.（3）RPVB/PVC blends were prepared by solution blending method and melt blending method respectively,and 0.2 phr hexamethylene diisocyanate（HDI）was added to cross-link the systems.Compared with the solution blending,the degree of cross-linking of the melt blending was larger,and the adhesion between the two phases of RPVB and PVC in the blend was stronger,and the phase domain size was smaller.Both solution blends and melt blends exhibit a wide glass transition and own good double shape memory performance.However,the performance of triple shape memory is very different between them,and the melt blend is obviously better than the solution blend.In the melt blending system,when the PVC content is 20%,the R_fof the first temporary shape and the second temporary shape are 80.3%and 98.6%,and the R_rof the first temporary shape and the permanent shape are 92.6%and 90.5%,respectively.（4）Some plasticizers in RPVB were extracted,polymer was crosslinked with HDI,catalyst dibutyltin dilaurate（DBTDL）was added to make polymer have plastic characteristics.The results show that crosslinked RPVB can relax to zero stress at160℃and show good permanent shape reconfiguration.Crosslinked RPVB has repeatability,and its mechanical properties do not change significantly after reprocessing.