Abstract
Abstract
Cellular or sponge rubber can be by expansion of fluid state by gas produced from decomposition of foaming agents [1]. It can be manufactured from various types of rubber and chemicals depending on properties required [2]. Natural rubber can give excellent mechanical properties except for thermal ageing [3]. The objectives of this work were to improve thermal ageing of NR foam by incorporating chloroprene rubber, CR, into NR and foaming NR/CR blends. In order to study the effects of the type of chemical blowing agents on the properties of cellular NR/CR rubber blends, azodicarbonamide (ADC) and oxybisbenzenesulfonyl hydrazide (OBSH) were used as blowing agents and compared. The cure characteristic, mechanical, morphological, and flammability properties of the foams were investigated. The results indicated an increasing chloroprene rubber loading caused the increase in cure time, but decreased in cure rate index. In both cases of foaming agents, the cellular rubbers were found that tensile and tear strength were decreased with CR rubber loading, but the secant modulus and hardness were increased. Compression set was decreased with CR rubber loading. It is also showed that the flammability of NR/CR foam with high CR contents (more than 80%) was better than that with low CR contents. It is also found that using OBSH as foaming agent can produce cellular rubber containing better cell density and cell size distribution than ADC.