Study On Synthesis Of High Molecular Weight Poly(Vinyl Alcohol) By Using Emulsion Polymerization

The water soluble azoinitiator—azobis(isobutylamidine hydrochloride) was synthesised by base catalysis method. Its chemical structure was characterized by IR and HNMR . The optimal technical conditions were determined through orthogonality experiment. The kinetic of thermal decomposition was measured. The results show that the decomposition is first-order reaction and the decomposition activity energy is 67.39kJ/mol.The emulsion polymerization of vinyl acetate was studied using azobis(isobutylamidine hydrochloride) as initiator. The relative molecular weight and relative molecular weight distribution of poly(vinyl acetate) were tested by GPC. The optimal technological parameters were obtained by orthogonality experiments. The effects of monomer concentration, initiator concentration, emulsifier concentration and temperature of polymerization on the viscosity average molecular weight of poly(vinyl acetate) were investigated. The result indicats that the viscosity average molecular weight of poly(vinyl acetate) achieves 9.8×10~5.The emulsion polymerization kinetics of vinyl acetate was studied. The influential factors to the polymerization rate of vinyl acetate were discussed. The results indicate that the polymerization rate expression is and the apparent activation energy of polymerization is 47.86kJ/mol.The effects of alcoholysis factors on the alcoholysis degree of poly(vinyl alcohol) were discussed. The optimal technological conditions of alcoholysis for high molecular weight poly(vinyl acetate) were obtained. The poly(vinyl acetate) with 9.8×10~5 viscosity average molecular weight was alcoholyzed under the optimal alcoholysis conditions. The experimental results indicate that: the viscosity average molecular weight of poly(vinyl alcohol) is 4.1×10~5 and the alcoholysis degree is 99.16%.