THE EFFECTS OF A MULTIFUNCTIONAL ADDITIVE ON CURING CHARACTERISTICS,MECHANICAL PROPERTIES,AND SWELLING BEHAVIOR OF NATURAL RUBBER/POLYCHLOROPRENE RUBBER BLENDS

The effects of a diamine salt of fatty acid of general structure RNH₂ ⁺CH₂)₃NH⁺] R′COO^?]₂ referred to as a multifunctional additive (MFA) on curing characteristics and mechanical properties and swelling behavior of natural rubber (SMR L) and polychloroprene (CR) rubber blends were studied. Compared to SMR L/CR blends without MFA, the incorporation of 2 phr (parts per hundred parts of rubber) of MFA in the blends increased mechanical properties, i.e., tensile strength, tensile modulus and hardness, and improved swelling resistance toward toluene and ASTM oil No. 1. However the scorch time, t ₅ and cure index, Δt _L decrease with incorporation of MFA into the blends.