Dichlorocarbene modified butadiene rubber (DCBR): Preparation, kinetic study, and its properties in natural rubber/DCBR blend vulcanizates

TLDR: In this article, a dichlorocarbene modified butadiene rubber (DCBR) was prepared via the addition of the dichloromethane group in the presence of two phase transfer agents (cetyltrimethylammonium bromide and tetraethylammium chloride) and the effects of the reaction temperature and time, amount of dichloroxarbene precursor, and the type and amount of phase transfer agent on the chlorine content were investigated.

Abstract: Dichlorocarbene modified butadiene rubber (DCBR) was prepared via the addition of the dichlorocarbene group in the presence of 2 phase transfer agents (cetyltrimethylammonium bromide and tetraethylammonium chloride). The effects of the reaction temperature and time, amount of dichlorocarbene precursor, and the type and amount of phase transfer agent on the chlorine content were investigated. The highest chlorine content (30%) in DCBR was obtained using 0.062 mol chloroform and 0.003 mol cetyltrimethylammonium bromide at room temperature for 19 hours although 27.9% was obtained after 12 hours. The kinetics of this dichlorocarbene modification was best described by the pseudo–first order rate law with 2 rate constants. For practical applications, the DCBR with chlorine contents of 10%, 20%, or 30% were blended with natural rubber (NR) and then vulcanized using the sulfur-curing system. Although the polarity of DCBR was increased, a good compatibility between NR and DCBR still existed, resulting in improved mechanical properties. The oil resistance, flame retardant, and ozone resistance properties of the NR/DCBR blend vulcanizates were enhanced compared to those of a NR/butadiene rubber blend vulcanizate, which was related to the amount of chlorine incorporated into the DCBR.