THE INFLUENCE OF CURING SYSTEMS ON THE PROPERTIES OF BROMOBUTYL RUBBER .2. EFFECT OF CONCENTRATION OF CURING RESIN ON THE DYNAMIC MECHANICAL-PROPERTIES

Measurements of isochronal dynamic mechanical properties of cured, uncured and thermally aged rubber vulcanizates have been carried out using a Rheovibron DDV-III-EP elasticoviscosity meter as a function of temperature between -150°C and +250°C. The effects of curing resin (phenol/formaldehyde[resole] resin; SP-1045) concentration and time of heat ageing on different relaxation transition characteristics and dynamic mechanical properties have been discussed. It has been observed that the molecular mobility is not affected, but only the sensitivity of E (in-phase modulus) in the dispersion region is affected by resin content and time of ageing. With increase in resin content in the vulcanizate, on ageing, the crosslinking reaction becomes more predominant over degradation of polymer chains and scission of crosslinks. © 1990.