BULK AND SURFACE COMPRESSION FLOWS OF POLYMER MELTS

Bulk (tridimensional) and surface (bidimensional) compression behaviour of several polymers [isotactic polypropylene, 1,2 syndiotactic polybutadiene, polyisobutylene, poly(methyl methacrylate), low density polyethylene, 1,4 cis-polybutadiene, polystyrene, poly(butylene terephthalate), poly(vinyl chloride) is described. Longitudinal bulk viscosity increases with decreasing bulk compression rate, with decreasing and increasing temperature (according to their chain rigidity), and with increasing compression deformation; bulk modulus of elasticity is a function of intrachain interactions. Surface tension and surface compression modulus of elasticity are both ca 20-70 mN/m. Surface compression viscosity (eta-K(s) approximately 100,000 surface poise) increases as the bulk pressure increases, the surface compression rate decreases, the polymer intermolecular interactions decreases, and the temperature decreases. Surface compression flow activation energy is ca 2.0 kJ/mol.