CHARACTERIZATION OF THE NATURAL-RUBBER VULCANIZATES OBTAINED BY DIFFERENT ACCELERATORS

Zinc diethyldithiocarbamate (ZDEC) is one of the most commonly used ac celerators in natural rubber latex technology because of the propertie s of the corresponding vulcanizates. Many studies using this accelerat or have shown the presence of carcinogenic nitrosamines and therefore its unsuitability for the production of some goods. The possibility of the substitution of the accelerator zinc diethyldithiocarbamate with zinc mercaptobenzothiazole, diphenylguanidine, or their combination, i n the vulcanization of NR latex films was investigated. Four series of films were prepared by sulphur vulcanization, changing the accelerato r and accelerator's concentration in a latex composition. The data cov ering the estimation of the network structure through crosslink densit y and distribution of different crosslink types, mechanical properties , and resistance to heat and ozone degradation are presented. The infl uence of the type and concentration of accelerators on these propertie s of vulcanized films was considered. The results show that the combin ation of accelerators zinc mercaptobenzothiazole/diphenylguanidine may be regarded as a proper substitute for zinc diethyldithiocarbamate as far as good film properties are desirable. Copyright (C) 1996 Elsevie r Science Ltd