Study On The Emulsion Terpolymerization Of Acrylonitrile-Butadiene-Isoprene

NBR was widely used in a variety of oil products because of its good oil resistance and solvent resistance. With the development of building materials and automobile industry, the requirements of NBR's performance is stricter. As the low tensile strength and elongation at break, the application of NBR is limited. In this paper, we have first synthesized the acrylonitrile-butadiene-isoprene copolymer with the copolymerization of acrylonitrile, butadiene and isoprene. The rate of emulsion terpolymerization, structure and properties were investigated with the major conclusions:The effect of different temperature, amount of initiator, emulsifier, molecular regulator, electrolyte, water monomer ratio and monomer ratio on the rate of emulsion terpolymerization was investigated. The results showed that polymerization rate increased with the temperature, the amount of the emulsifier or initiator, a little of electrolyte, water and acrylonitile increasing; the amount of molecular regulator or butadiene isoprene ratio had little effect on the rate of copolymerization. The polymeration rate decreased if the electrolyte too much.The structure and properties of copolymer were investigated with different monomer ratio, different temperature and different accessory ingredient on the amount. The results showed that when the amount of acrylonitrile was 33, with the isoprene increasing, the combining acrylonitrile content of copolymer were 33.5% around, the content of trans 1,4-unit of polybutadiene increased, cis 1,4-unit of polybutadiene decreased and 1,2-units of polybutadiene decreased a little; the content of trans 1,4-unit of polyisoprene increased, cis 1,4-unit of polyisoprene decreased and 3,4-units of polybutadiene was effect little. The break elongation was increased with isoprene increasing, but there was no effect on tensile strength and the oil resistance. The tensile strength and modulus at 300% were maximum when butadiene and isoprene ratio of 1:1. When butadiene and isoprene ratio was 1:1, with the acrylonitile increasing, the combining acrylonitrile content of copolymer increased, the content of trans 1,4-unit of polybutadiene decreased, cis 1,4-unit of polybutadiene increased and 1,2-units of polybutadiene; the content of trans 1,4-unit of polyisoprene decreased, cis 1,4-unit of polyisoprene increased and 3,4-units of polybutadiene increased a little. The tensile strength, modulus at 300%, hardness (Shao A) and the oil resistance were increased with acrylonitrile increasing, but the break elongation decreased. The temperature had greater influences on composition and microstructure of copolymer but the amount of accessory ingredient had little effect.The molecular weight, molecular weight distribution and Tg were investigated with different monomer ratio, different temperature and different accessory ingredient on the amount. The results showed that butadiene and isoprene ratio had little effect on the molecular weight and Tg increased with isoprene increasing. With increasing of acrylonitrile amount, the molecular weight and Tg were increased. The temperature of polymerization rised, the molecular weight increased and the molecular weight distribution became wider. Increased the amount of emulsifier could both increase the molecular weight and its distribution. The molecular weight and molecular weight distribution were decreased with the initiator dosage increasing. The molecular weight had changed a large amount with the amount of chain transfer agent. The molecular weight and molecular weight distribution were decreased with chain transfer increasing.