The Foaming Performance Biowing With Supercritical CO₂ And Shape Memory Property Of TPI

In this paper,the supercritical carbon dioxide foaming properties and shape memory properties had been studied of Ttrans-1,4-polyisoprene(TPI)materials:Dicumyl peroxide(DCP)as vulcanizater and supercritical carbon dioxide(SC-CO2)fluid as foaming agent,two kinds of process of pre-crosslinking by heat press and pre-crosslinking in kettle were used to prepared TPI foams.First process was that TPI materials w ith different DCP content w ere vulcanizing by heat presse and then been foamded in a batch foaming kettle.Second process w as that TPI materials w ith different DCP content w ere molding by heat presse and then been curing-foamded in a batch foaming kettle.The effects of DCP content and foaming process on the properties of TPI materials and TPI foams were investigated.Meanw hile,the shape memory properties of TPI foams w ere studied,and the mechanism of shape memory effect(SME)w as discussed.The results show ed that w ith the increase of DCP content,the equilibrium sw elling degree and the crystallinity performances of TPI materials w ere decreased.For the TPI foams prepared by the first process,w hen the saturation temperature w as low(T<Tm),the addition of DCP c ould improve the foaming property and w hen the saturation temperature w as high(T>Tm),the expanding ratio and the average cell size w ere larger than those at low temperature.When DCP content increased,expanding ratio decreased and average cell size increased.The expanding ratio and the average cell size increasee first and then decreased,and reached the maximum value at 80 degree celsius w ith the increase of saturation temperature.When saturation pressure increased,expanding ratio and average cell size decreasd.For the TPI foams prepared by the second process,the expanding ratio and the average cell size decreased w ith the increas e of DCP content,w hile cell density increased and regularity of cell morphology improved.Increasing the saturation temperature and increasing DCP content had the same effects.It can be seen by the shape memory tests that TPI foams had good shape memory properties.With the increase of DCP content,shape fixed rate,shape recovery rate and shape recovery speed of TPI foams w ere increased.When the content of DCP w as 3phr,TPI foams had the best shape memory performances.Shape fixed rate and shape recovery rate were 100% and shape recovery time was 10 s.When the foaming density of the TPI foams w as big,shape fixed rate,shape recovery rate and shape recovery speed of TPI foams w ere good.Trans-1,4-polyisoprene/high isotactic polybutylene-1(TPI/iPB-1)blending materials and crosslinking TPI/iPB-1 blending materials w ere prepared by melting blend method.Effects of TPI/iPB-1 blending ratio and DCP content on mechanical properties,thermal properties,crystallization properties and micro-morphology w ere studied.Two kinds of materials w ere foamed by SC-CO2 fluid.The effects of TPI/iPB-1 blending ratio,DCP content,saturation temperature on the foaming properties and shape memory properties w ere investigated.The results w ere as follows: SEM w as used to observe the micro-morphology of TPI/iPB-1 blending materials,which telled that materials show ed a sea-island structure.With the increase of iPB-1 content,the mechanical properties of TPI/iPB-1 materials decrease to some extent.When 10wt% iPB-1 w as added,the TPI/iPB-1 foams had a regular pore morphology and high expanding ratio.TPI/iPB-1 foams had good shape memory properties.When the iPB-1 content increased,the shape fixed rate decreased w hile the shape recovered rate and shape recovered speed increased.When the foaming density increased,the shape fixed rate increased w hile the shape recovered rate and shape recovered speed decreased.For the crosslinking TPI/iPB-1 materials,DCP can reduce the tensile properties and crystallization properties,and improved the impact properties.SEM images of crosslinking TPI/iPB-1 blending materials showed that the addition of DCP improved the compatibility by improving the interface adhesive ability.When DCP content w as 0.4phr,foaming properties can be effectively improved.When 0.8phr DCP w as added,low er expanding ratio and average cell size w ere got.Crosslinking TPI/iPB-1 blending materials had triple shape memory effect.When iPB-1 content increased,crosslinking TPI/iPB-1 blending materials had good shape fixed rate and bad shape recovery rate.With the inc rease of DCP content,Rf(0-1)w as almost unchanged,and Rf(1-2)and Rr(2-1)increased.