STUDIES ON A NEW BINARY ACCELERATOR SYSTEM CONTAINING TMTD AND AMIDINOTHIOUREA IN SULFUR VULCANIZATION OF NATURAL-RUBBER

It is well known that the use of binary accelerator systems in rubber vulcanization provide better physical and chemical properties to the v ulcanizates. The present work reports the results obtained on the stud y of amidinothiourea as a secondary accelerator along with tetramethyl thiuram disulfide (TMTD) in the sulfur vulcanization of natural rubbe r. Vulcanizates containing amidinothiourea have an appreciable increas e in mechanical properties and better retention of these properties af ter aging compared to the reference mixes used. These mixes containing amidinothiourea showed appreciable reduction in optimum cure time as well. This suggests a nucleophilic reaction mechanism in the vulcaniza tion reactions under review. Mixes with varying concentrations of amid inothiourea were tried; and the optimum level of amidinothiourea requi red has been derived based on the cure characteristics of the mixes an d physical properties of the vulcanizates. (C) 1994 John Wiley and Son s, Inc.