Studies on the mechanical properties in compression of porous polypropylene

Studies on the blow molding processing and selected compression properties of thermoplastic polymers have been presented. The compression strength of polypropylene (PP) obtained in the extrusion blow molding process with 0 ÷ 2 wt. % content of blow agents of endothermic decomposition character has been determined (Fig. 5). Samples of dimensions h - 30 mm and Φ - 20 mm, (Figs. 1 and 2) were subjected to compression in a test apparatus (Fig. 3) under steady loading/unloading cycles (dual ramp) in the 0 ÷ 30 kN range and also in a stepwise loading/unloading procedure (every 5 kN with breaks) in the 0 ÷ 25 kN range (Fig. 4). The performance of selected polymeric products were determined on the basis of stress/strain curves and the following determined relations: the dependence of strain of the studied samples on the static load values obtained for various amounts of blowing agent feed (Figs. 6-11), Young's compressive modulus on the amount of blowing agent (Fig. 12) and also work done during the compression on the amount of blowing agent (Fig. 13). The dependence of the relative deformation of porous PP on the increase in values of the parameters of steady loading/unloading cycles was also determined.