Synthesis And Properties Of Styrene-Butadiene Transparent Impact Resin

Styrene-butadiene transparent impact resin had high transparency and impact resistance, low cost, nontoxicity, and good processability with widespread application. It was synthesized by two-stage addition of initiator, three-stage or more addition of monomers, and forming one or multiple random progressive segments in the molecular chain, then by the process of coupling in the abroad. The copolymer solution was post-treated by concentration and twin screw devolatilization process. In this paper, the transparent styrene-butadiene impact resin was synthesized with cyclohexane as solvent, tetrahydrofuran as activating agent, n-butyl lithium as initiator, γ-glycidoxy propyl-trimethoxy silan as coupling agent, by one-stage addition of initiator and two-stage addition of monomers and one-arm molecular chain end modified with butadiene, and then by adding coupling agent.The effects of impurities, such as water, oxygen, carbon dioxide, alkyne and alcohol on the anionic solution polymerization were discussed. Based on the initiating rates in homogeneous polymerization and copolymerization of styrene and butadiene in different solvents, using cyclohexane as solvent had better comprehensive properties in the synthesis of styrene-butadiene transparent impact resin. The addition of tetrahydrofuran had greater effects on the activity of n-butyl lithium the homogeneous polymerization and copolymerization of styrene and butadiene, and the micro-structure of butadiene chain. The theoretical model of the relationship between the amount of tetrahydrofuran and the 1,2-unit in polybutadiene chain was derived by chemical dynamics and two probability methods by the investigation of anionic solution polymerization mechanism of butadiene. On this base, a semiempirical model was established, and the undetermined parameters in the semiempirical model were solved combined with the experimental data. The maximization of degree of superheat and its three forms of the transparent styrene-butadiene impact resin solution in the falling-strand devolatilization process were stated. The layout of the exhaust stage and outlet in the devolatilization process was determined according to the relationship among the discharge efficiency and material flow, extent of admission, residence timeand shear strain. The process route for the polymerization and post-treatment of transparent styrene-butadiene impact resin was determined by detailed argumentation. The main conditions of the polymerization process was studied, such as the conversions of the homogeneous polymerization and copolymerization of styrene and butadiene, relationship between temperature and polymerization time, mechanism of coupling reaction, amount of coupling agent, relationship between coupling ratio, intrinsic viscosity and coupling time. The mathematical model of polymerization recipe and process of transparent styrene-butadiene impact resin was established by secondary regression orthonormal rotary combined design. The optimal polymerization recipe and process conditions were solved by optimum calculating method. The mass ratio of styrene/butadiene was 76724, the mole ratio of styrene/butadiene in random segments was 0.894, the charge time of random segments was 17 min, the mass fraction of terminal modified butadiene was 10% of total butadiene.The engineering amplification of reactor was cold simulated based on the model test. The effect of agitator blade, simulated fluid and kettle diameter on agitator power, and the effect of feed position, viscosity, kettle diameter and agitator blade on mixing time were studied. The results showed that using two tier and four blade inclined paddle in the pilot reactor was suitable. According to the cold simulation, the optimal polymerization recipe and process conditions were verified in the established pilot plant. The parallel stability test showed that the established polymerization recipe and process mathematical model were reliable and practical, and could be used for guiding the pilot test. The synthesized transparent styrene-butadiene impact res...