Physikalische Untersuchungen an vernetzten Hochpolymeren

Abstract

The effect of chemical cross-links on the elastic properties and the position of the glass temperature is discussed by showing the example of natural rubber which was cross-linked by means of sulfur, peroxyd and radiation. Cross-links reduce the crystallinity of partial crystalline high polymers and render the diffusion of low molecular substances more difficult. With polyester resins the diffusion rate is determinant for the curing. Apart from primary valence cross-links physical cross-linkage can occur because of ordering effects or secondary valence forces. Entanglements, molecular associations, fillers, crystalline regions and amorphous blocks act within limited temperature ranges as physical cross-links. In all these cases the temperature dependence of the dynamic mechanical moduli is a good criterion for configurational elasticity.