سنتز كوپليمر وينيل استات -اتيلن به روش پليمرشدن امولسيوني ناپيوسته : 1- بررسي اثر فشار

Synthesis of Vinyl Acetate-ethylene Copolymer Through Batch Emulsion Polymerization,I:Effect of Pressure

Emulsion polymerization of vinyl acctatc-clhylcnc copolymer is carried out in a pressure reactor. Control of parameters such as pressure, temperature, raw materials concentration, etc., is essential since they have determining roles in the final properties of the latex, vinyl acetate conversion and the ethylene content of the copolymer. Meanwhile pressure has an opposite effect. Increasing pressure up to 35 atm would increase ethylene participation in the polymerization reaction and at the same time it decreases vinyl acetate conversion due to the hindrance effect of ethylene in vinyl acetate polymerization. Decreasing pressure reduces ethylene presence in the polymerization reaction leading to a high conversion rate of vinyl acetate and a decrease in ethylene content of the copolymer. As a result, a medium pressure of 23 atm was chosen to reach a simultaneous increase in ethylene content and conversion. Glass transition temperatures (Tg) of the copolymers were also investigated.