Flame retardant and durable chloroprene rubber and styrene-butadiene rubber blends crosslinked with copper(I) oxide

Abstract

The purpose of this work was to investigate the effect of application of copper(I) oxide (Cu2O) as an unconventional crosslinking agent of chloroprene (CR) and styrene-butadiene (SBR) rubber compositions. The use of Cu2O arises from the need to limit the application of ZnO as a CR crosslinking agent. The obtained results indicate that CR/SBR blends crosslinked with Cu2O are characterized by good mechanical properties and a high degree of crosslinking The results show that the proportion of both processing rubbers, as well as the amount of copper(I) oxide, influence the crosslinking of CR/SBR blends and the properties of the vulcanizates. Performing FTIR analysis has allowed the development of a crosslinking mechanism. Crosslinking presumably takes place according to the mechanism of Friedel–Crafts alkylation reaction. Silica, chalk, china clay and nanofiller (montmorillonite modified with quaternary ammonium salt containing hydroxyl groups) were applied as fillers. Among the fillers, silica had the greatest impact on improving the properties. It is arisen from silica activity, unlike other used fillers. The AFM analysis allowed us to determine the miscibility of the rubbers and dispersion of fillers. Thermal analysis was performed to determine the changes occurring as a result of material heating. The low intensity of the peaks corresponding to the crosslinking of the CR/SBR blends may indicate a small amount of bonds formed during heating, or possibility is the formation of connections between chains with a low binding energy. The use of chalk, china clay or silica increases the thermal stability of the vulcanizates. Obtained vulcanizates were characterized by increased incombustibility. The study of combustion time in the air showed that the prepared vulcanizates did not support the burning.

Cross-Link Density, Mechanical and Thermal Properties of Chloroprene Rubber Cross-Linked with Silver(I) Oxide

“…The Lewis acid catalyzes the bonding of CR chains. The cross-linking according to this mechanism occurs when other metal oxides are used, such as the standardly used zinc oxide [ 35 ] or copper oxides [ 13 , 15 ]. There is also a noticeably close to linear relationship between the cross-link density and the cure rate index ( Figure 2 ).…”

“…Chloroprene rubber is often used in blends with other rubbers, for example, butadiene rubber (BR) or styrene-butadiene rubber (SBR). In such materials, metal oxides can be used for the cross-linking: copper oxides [ 13 , 14 , 15 ] or iron oxides [ 16 , 17 ]. In the case of blends of chloroprene rubber with natural rubber (NR), ethylene thiourea as accelerator can be replaced by an alkanolamide [ 18 ].…”

“…The regulations result from the harmful effects of ZnO on aquatic organisms. As an alternative to CR cross-linking agent, other metal oxides such as copper oxides [ 13 , 14 , 15 ] or iron oxides [ 16 , 17 ] can be used. Ag 2 O as a CR cross-linking agent has not been described in the literature so far, which made the following results possible as presented here.…”

The Use of Copper Oxides as Cross-Linking Substances for Chloroprene Rubber and Study of the Vulcanizates Properties. Part I

“…Copper oxides and iron oxides can substitute zinc oxide and magnesium oxide in the cross-linking of chloroprene rubber, chlorosulfonated polyethylene, or chlorobutyl rubber. Copper oxides and iron oxides are also effective in cross-linking CR and chlorosulfonated polyethylene (CSM) mixtures with styrene-butadiene rubber and butadiene rubber [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

“…As an alternative to ZnO, different metal oxides can be used as a cross-linking agent. The choice of copper oxides results from the ability to cross-link CR blends with styrene-butadiene rubber (SBR) or butadiene rubber (BR) [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. The advantage of using copper oxides is the smaller amount needed for cross-linking elastomer blends containing CR compared to other cross-linkers.…”