Extrusion Foaming Behavior of Different Polypropylene Foaming Systems

Effect of heating rates on the thermogravimetric behavior of endothermic chemical foaming agent (HP40P) and exothermic chemical foaming agent (azodicarbonamide) was studied.Extrusion foaming behavior of linear polypropylene(LPP)/long chain branching polypropylene (LCBPP) blend and LPP/nano-clay composite were investigated.The results showed that endothermic chemical foaming agent exhibited a wide decomposition temperature range.It was necessary to increase the screw rotating speed to inhibit the decomposed gas loss when the endothermic chemical foaming agent was used for polypropylene foaming.The polypropylene foam with cells about 100 ttm in size and cell density of near 10~6 cells/cm~3 was produced by the use of LPP/L,CBPP/HP40P foaming system.No serious rupture and coalescence of cells were found in the extrusion foaming of linear polypropylene/nano-clay composite, Dynamic shear rheological results showed that the linear polypropylene/nano-clay composite exhibited excellent melt elasticity.