Study Of Blending Modification And The Foaming Properites Of PP/SEBS Blends

In recent years,Polypropylene(PP)foamed materials have a wide potential promising applications in the fields of packaging,food,automobiles,construction,etc.Due to their advantages of high cost-effectiveness,good insulation,good heat resistance,light weight,and good mechanical properties.However,the linear molecular structure of PP leads to its low melt strength,rupturing and collapsing of cells can easily occur during the foaming process.Therefore,in order to improve the foaming quality of PP,the elastomer SEBS was used to blend and modify PP in this paper.(1)Mechanical properties,thermal properties,flow properties,and rheological behavior of PP/SEBS composites;(2)Thermal properties and foaming properties of PP/SEBS foams prepared by batch foaming with supercritical CO2;(3)The foam morphology and mechanical properties of PP/SEBS foams prepared by the rapid pressure relief foaming method of home-made foaming moulds were studied.(1)The results of modification by blending showed that the crystallinity of PP was reduced after the addition of SEBS,and the melting temperature and crystallization temperature did not change.The tensile strength and flexural strength decreased,the impact strength increased significantly.The impact strength was 73.12 k J/m2 when the SEBS content was 20%,which was 16.5 times that of pure PP.The flow properties of the process increased first and then decreased,and the flowability was best at 10%.The complex viscosity becomed large,and it becomed maximum at 20%.(2)The results of batch foaming with supercritical CO2 showed that with the increased of SEBS content,the melting temperature decreased and the crystallinity first increased and then decreased.as the cell size becomed smaller,the cell density becomed larger.The melting temperature increased with the saturation time increased.The melting temperature increased first and then decreased with the saturation pressure increased and the crystallinity did not change significantly.The saturation temperature increased,the melting temperature increased,and the crystallinity decreased.At 164oC,double melting peaks appeard.When the saturation time,pressure and temperature increased,the average cell diameter decreased,and the cell density increased.When the SEBS content,saturation time,pressure,and temperature was 20%,40 min,14 MPa,and 160oC respectively,the morphology of the cells was the best and the average cell diameter was 5.5 ?m,the cell density was 2.6×109 cells/cm3.(3)The rapid pressure relief and foaming of the home-made foam mold showed that with the increased of SEBS content,the cell size and the cell density gradually decreased,the tensile strength and impact strength decreased,the flexural strength increased,and increased about 19% compared with unfoaming.The cell size and cell density showed an increasd trend with the increased of saturation pressure and saturation time.With the increased of saturation pressure,the tensile strength,flexural strength and impact strength decreased.With the increased of sturation time,the impact strength decreased,the tensile strength and flexural strength increased,and flexural strength increased by about 12%.