Research And Production Of Polyvinyl Alcohol With High Degree Of Polymerization

Polyvinyl alcohol(PVA)is one kind of versatile water-soluble polymers which is widely used in the production of vinylon,textile slurry,paint,adhesive,emulsifier,paper processing aids,film,and so on.In this paper,the preparation of polyvinyl alcohol with high degree of polymerization via solution polymerization and low alkalinity alcoholysis process using methanol as solvent was completely studied.The results indicated that methanol ratio in the polymerization process,initiator amount of azodiisobutyronitrile(AIBN),and rate of polymerization are the main influencing factors for the production of PVA with high degree of polymerization.Rheological properties of polymerization and alcoholysis process were studied respectively in order to understand these two processes better.The results show that methanol solution of PVAc is a shear thinned non-Newtonian fluid with the non-Newtonian index is 0.56-0.65,and the rheological properties of the solution are consistent with the law of power exponent.The structure and property characterizations of the obtained products were also conducted with GPC,FT-IR,and TGA.On the basis of laboratory research,pilot production of PVA2499,2488 with high degree of polymerization was preceded using the existing 5000 tun/year multispecies PVA production unit with the adjustment of technological parameters.The effect of methanol ratio,polymerization rate and alkli mole ratio on the the production was summarized,and our own process technology was developed and its optimization was discussed to table a proposal for better production in the future.