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White flake or floc , polyvinyl alcohol (PVA) , non-toxic , tasteless, has good mechanical properties and adjustable surfactant , is widely used in the textile, construction , packaging , polymer and chemical industry soluble polymers. PVA, degree of polymerization and degree of alcoholysis determine its nature and range of applications, the present study analyzed the reaction temperature, reaction time , PVAc and PVA degree of polymerization initiator agent and solvent and other factors , PVAc molecular weight distribution was measured by gel chromatography , Albright viscometer PVA having an average polymerization degree of the PVAc judgment polymer molecular weight difference before and after the branched alcohol solution , the use of infrared spectroscopy to characterize the PVA . Azobisisobutyronitrile as the initiator and methanol as solvent , using a solution polymerization , with step in a water bath temperature of 70 ° C when synthetic PVAc was added methanol solvent method of methanol through regulation ratio regulating the degree of polymerization of the PVA , Synthesis of a higher degree of polymerization of the PVA process parameters : the amount of initiator is added to 0.00065% of the monomer mass , the solvent content of 20% , two steps Add 11% to 10.28% , the ratio of the stepwise addition , reaction time is 2.5h 2.5h, the conversion was 32.82% , the PVAc was an average polymerization degree of 3311 , the PVA having an average polymerization degree of 3083 , Mw / Mn of 1.549 . Vinyl acetate conversion with the reaction time and improve the polyvinylalcohol degree of polymerization with the reaction time extended first gradually increased , and subsequently increased to a certain optimum value decreased with time , by controlling the reaction time to balance vinyl acetate the relationship between the conversion ratio and the PVA polymerization degree , to obtain a higher degree of polymerization of polyvinyl alcohol , in a higher conversion rate , its optimal process parameters: the amount of initiator is added to 0.00065% of the monomer mass , solvent content of 20% , two steps Add 14.77% 6.32% , the ratio of the stepwise addition , the reaction time was 2.5h 2.5h , vinyl acetate conversion was 29.51% , the average degree of polymerization of the polyvinyl acetate is 2956, average degree of polymerization of the polyvinyl alcohol 2917 , Mw / Mn 142.4 ; reaction time was 2.5h 3.5h , vinyl acetate conversion was 44.94% , and the average degree of polymerization of the polyvinyl alcohol was 2588 .
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