Study On Synthesis And Characterization Of Structure-Controllable Core-Shell Copolymer With Toughing Fuction

On the basis of the study and development of core-shell polymer particles at domestic and abroad, a research on the synthesis and properties of core-shell polymer material using for toughening material was made. The main objective is to get such particles that core polymer molecular weight and vinyl content can be controlled, so that the toughening principles by which the core-shell polymer particles toughen plastics can be further studied.Polybutadiene (PB) that its molecular weight and vinyl content can be controlled is synthesized by anionic polymerization technique in the first step, polymerizing with n-BuLi as initiator, cyclohexane as solvent with the presence of polar addictive THF.To disperse PB to even latex is the main problem we have to conquer. It is found that when ammonium oleate or natrium oleate is used as emulsifier and higher stirring rate is employed, stable latex can be obtained. The homogeneous solution of polybutadiene and oleic acid in cyclohexane, oil phase, is mixed with the water phase containing ammonia or sodium hydroxide bystirrer for 30 min. As the ammoniated water is gradually added to and stirred into the rubber solution, the water first forms the disperse phase of the emulsion. As the total volume of added water increase, a change of phase occurs, and the water then forms the continuous phase. The solvent, cyclohexane, can be removed by distillation. A small negative pressure is exerted on the latex to help cyclohexane removal. Core polymer particles have been synthesized whose diameters range from 50nm-2 m.Shell monomer MMA and K2S2O8 (initiator) are added into the former latex. Slow instillation, i.e. under a monomer "starved" condition can avoid creating PMMA homopolymer. Core-shell polymer particles have been synthesized whose diameters range from 60nm to 3 m.Blend the core-shell particles and epoxy resin, and make samples according to GB1043-79. The results showed that: the core-shell particles synthesized in this thesis have good toughening effect.