Physico-mechanical properties of polymers subjected to the simultaneous action of high pressure and shear deformation

Severe Plastic Deformation of Polymers

“…Thus, for polypropylene (PP) intensive destruction sets in at pressures in excess of 0.5 GPa, while for polyethylene (PE) this occurs for pressures above 1 GPa. 19) For a PP-ethylene propylene rubber composite, an increase of strength and elongation at break is observed when the anvil rotation angle is raised up to 400°. However, a drop in these characteristics occurs upon further increase of the anvil angle.…”

“…The greatest effect is attained at the rim of an HPT sample for the anvil rotation of about 100°. 12,19) The magnitude of HPT-induced re-structuring depends on the type of the polymer processed. 12,14,17,18) A substantial reduction of the molecular mass of homopolymers stemming from mechano-chemical destruction leads to a deterioration of their physical and mechanical.…”

“…12,14,17,18) A substantial reduction of the molecular mass of homopolymers stemming from mechano-chemical destruction leads to a deterioration of their physical and mechanical. 11,19) By contrast, in the case of polymer mixtures the properties can be improved by HPT, owing to a pronounced comminution of phases, their more uniform distribution and the formation of new crystal structures (cocrystallites). 14) The specifics of the mechano-chemical destruction process are dictated by the type of the polymer and the HPT process parameters.…”

“…However, a drop in these characteristics occurs upon further increase of the anvil angle. 18,19) HPT of hard monomers promotes the formation of macromolecular compounds. 16) The degree of polymerisation increases with growing pressure, process temperature, and the anvil rotation angle, i.e.…”

“…HPT can also lead to homogenisation of blends of thermodynamically incompatible polymers, as was demonstrated for PP-PE and PP-ethylene propylene rubber mixtures. 15,18,19) This is associated with mutual dissolution of amorphous regions of the constituents of the polymer blend by HPT, which cannot be achieved by mixing in the melt. Gradual increase of interaction between the phases due to plastic flow during HPT causes a decrease of the size of the dispersion phase particles, which improves the physical and mechanical properties of the composite.…”