| In this thesis,microcellular foamed EVA/POE/SEBS blended materials and EVA/silicone rubber blended foamed materials were successfully prepared by using supercritical nitrogen as foaming agent and intermittent foaming method.The blending ratio was studied.The influence of the bubble structure and physical and mechanical properties of the foam material.Supercritical fluid foaming of different formulas of EVA/POE/SEBS rubber compound,supercritical foaming of EVA/POE/SEBS rubber compound under different conditions,POE/SEBS content ratio,foaming condition Two main variables were analyzed for M_H,M_L,t90 and other vulcanization properties,density,hardness,tensile strength,elongation at break,tear strength,rebound resilience and other physical and mechanical properties.(1)In the experiment in which the foaming conditions were changed,the higher the foaming temperature,the lower the density of the obtained foamed material.The greater the foaming pressure,the lower the density of the foamed material formed.(2)The tensile strength value,tear strength value and hardness are basically unchanged with the increase of SEBS,and the rebound resilience decreases with the increase of SEBS content,and the elongation at break of the material is gradually increased;With the increase of SEBS content,the cell size gradually becomes larger,the cell thickness is gradually increased,and the cell distribution is more uniform.(3)Study the linear viscoelasticity,complex viscosity,elastic modulus,viscous modulus and loss factor of materials under different ratios of EVA/POE/SEBS.With the increase of SEBS content,the complex viscosity,viscous modulus and elastic modulus of the blended materials are increasing,and the loss factor is decreasing.(4)The dynamic compression properties of foamed materials with different EVA/POE/SEBS ratios include thickness,deformation value per unit volume energy absorption before compression,average stiffness,instantaneous stiffness and energy efficiency.With the increase of SEBS content,the deformation value,average stiffness and instantaneous stiffness of foamed samples are increasing,and the energy absorption and energy efficiency per unit volume are gradually decreasing.The supercritical fluid foaming of different proportions of EVA/silicone rubber compound was carried out.The experimental results were analyzed to analyze the vulcanization properties of M_H,M_L and t90,and the density,tensile strength and tear strength after foaming.Physical and mechanical properties such as resilience,compression performance,and continuous compression performance.(1)With the increase of silicone rubber content,M_L,M_H and M_H-M_L all show an increasing trend,and the changes of t10 and t90 are not very regular.(2)As the content of silicone rubber increases,the cell size gradually decreases,the uniformity decreases,and the degree of cell rupture increases.The cell wall of the pure EVA foaming material is thin,the cell size is large and the distribution is uniform;when the content of the silicone rubber is 20-30 phr,the cell size becomes smaller and the uniformity decreases;when the silicone rubber content is 40-50 phr,The cell shrinks severely.(3)With the increase of silicone rubber content,the hysteresis curve shows a downward trend as a whole,which means that the compression modulus of the composite foaming material shows a downward trend as a whole.Under the same strain,the silicone rubber content is more.The higher the modulus of the foamed material,the higher the modulus of the composite foamed material to which no silicone rubber is added,and the modulus of the composite foamed material to which 50 phr of silicone rubber is added is the lowest.(4)As the content of silicone rubber increases,the overall modulus of the composite foamed material shows a downward trend.In addition,the hysteresis loop area of the curve can be seen to be obvious.Decrease,the hysteresis factor shows a downward trend,but the hysteresis loss rate shows an upward trend.In the TPI blend supercritical foaming experiment,with the increase of BR content,the expansion ratio and permanent deformation of TPI/BR blended foaming materials are decreasing,the density is increasing,and the foaming effect is getting worse.The ratio of 70/30,the blended foamed material has high tensile properties and tear properties.With the prolongation of vulcanization time(8min,12min,16min),the mechanical properties of TPI/BR blended foamed materials showed a downward trend.The ratio of TPI/BR/NR is 40/20/40,and the material after blending vulcanization foaming has higher crosslinking degree,higher tensile property and tearing performance,but the foaming effect is worse.The effect of vulcanization time of 8 min or 10 min on the performance of TPI/BR/NR blended foamed material was not obvious. |
PDF Full Text Request