Hardening Agent for Rubber Matrix

Liquid polybutadienes without functional groups may be vulcanized on double bonds of the diene part of the polymeric chain in the presence of a sulfur-accelerating, redox, or peroxide system. However, only the sulfur-accelerating system is able to provide the maximal durability values. Sulfur also has other advantages such as low price, availability, and so on. The amount of involved sulfur in the system depends on the desired properties of the product. For hard RubCon, this is 47-55 mass parts per 100 mass parts of rubber. 

The rising of the rate of chemical reactions between sulfur and rubber, acceleration of the vulcanization, and reduction of its temperature are accomplished using special accelerators. The use of a few accelerators may improve the vulcanization process because of their mutual activation. Two accelerators were used tetramethyl-thiuram-disulhde (thiuram-D) and CAPTAX . They act mutually and thus improve the vulcanization process and the resulting properties of RubCon. 

The previously mentioned suggestion has been tried in a two-phase experiment in which the variable parameters were the amounts of accelerators, and the value of RubCon durability as the function. 

It has been found from experience that the maximal value of RubCon durability is obtained at the CAPTAX content of 0.05 mass%, and thiuram-D 0.35 mass%. The maximum durability against compression has been found at a maximum content of thiuram-D and moderate content of CAPTAX. 

Regression analysis of the experiment results provides the following empirical equations  

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