Abstract
Opalized white tuff (OWT) with 40 μm average particle size and 39.3 m2/g specific surface area has been introduced into polyisoprene rubber (NR). Their reinforcing effects were evaluated by comparisons with those from precipitated silica (PSi). The cure characteristic, apparent activation energy of cross-link (E ac) and reversion (E ar), and mechanical properties of a variety of composites based on these rubbers were studied. This was done using vulcanization techniques, mechanical testing, and scanning electron microscopy (SEM). The results showed that OWT can greatly improve the vulcanizing process by shortening the time of optimum cure (t c90) and the scorch time (t s2) of cross-linked rubber composites, which improves production efficiency and operational security. The rubber composites filled with 50 phr of OWT were found to have good mechanical and elastomeric properties. The tensile strengths of the NR/OWT composites are close to those of NR/PSi composites, but the tear strength and modulus are not as good as the corresponding properties of those containing precipitated silica. Morphology results revealed that the OWT is poorly dispersed in the rubber matrix. According to that, the lower interactions between OWT and polyisoprene rubber macromolecules are obtained, but similar mechanical properties of NR/OWT (100/50) rubber composites compared with NR/PSi (100/50) rubber composites are resulted.
Highlights
Modern engineering systems are being increasingly produced from components that combine two or more materials for enhanced performance
The results showed that Opalized white tuff (OWT) can greatly improve the vulcanizing process by shortening the time of optimum cure and the scorch time of cross-linked rubber composites, which improves production efficiency and operational security
Usuki et al [10] prepared some EPDM/clay hybrids with montmorillonite, and the results showed that the tensile strength and storage modulus were improved and the permeability decreased 30%
Summary
Modern engineering systems are being increasingly produced from components that combine two or more materials for enhanced performance. Silica has been used as nonblack reinforcing filler in the rubber industry for a long time. Reinforced rubber blends are suitable materials for industrial practice [2]. In such systems both components (filler and rubber) have the reactive groups for the additional cross-linking reaction to take place [3]. A key one among them is hydrogen bonding, which tends to be a significant force in the case of fumed silica, where hydrogen bonding between surface silanol groups takes place. The surface of hydrated or precipitated silica is highly polar and hydrophilic because of the presence of numerous silanol groups [4, 5]. Many authors have investigated the role of filler networking in the elastic properties of elastomer composites [6,7,8,9]
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