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PVC suspension polymerization of PVA -based dispersant Development and Research

Author: HangYu
Tutor: YinWei
School: Kunming University of Science and Technology
Course: Chemical processes
Keywords: Polyvinyl acetate The degree of polymerization test Dispersant PVA-2486 Serialization distribution
CLC: TQ325.9
Type: Master's thesis
Year: 2010
Downloads: 125
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Abstract

Polyvinyl alcohol (PVA) is a special kind of water-soluble polymer, The polymerization degree and the alcoholysis degree are the two important factors that influence the performance of Polyvinyl alcohol products. The field of applications of Poly vinyl alcohol can be broadened via the control of two main factors to produce different varieties of Poly vinyl alcohol. The development of suspension polymerization of PVA system dispersant can not only increase the brand of Polyvinyl alcohol,but also break the monopoly place of abroad in the field of dispersant applications which has profoud significance.Vinyl acetate, azodiisobutyronitrile, methanol,polyvinyl acetate,sodium hydroxide,etc are main raw materials in this experiment.The target product polyvinyl alcohol 2486 can be prepared through polymerization and alcoholysis reaction. And molecular design theory can be used to research the preparation technics of disperse polyvinyl alcohol of Serialization distribution.Through the study of disperse series products of polyvinyl alcohol, the following meaningful research results are obtained.listed as follows:1. As intermediate product of alcoholysis reaction, the accuracy of test result of degree of polymerization of PVAc will inevitably affect the control of degree of polymerization of target product PVA. To solve the degree test of polymerization of Polyvinyl acetate, based on the data of polymerization degree in GPC test. PVAc is configured to certain concentration dilute solution in the experiment, which is approximate regarded as Newton fluid.The empirical formula of test of PVA 1nP= 4.72871n[η]/C+6.1796 is deduced through rotating viscometer. Then the method of Ubbelohde viscometer gradually extrapolation is uesd to measure degree of polymerization of PVAc.There are minor deviation and certain reliability among three methods.2. In the technics research of PVAc polymerization,methanol dosage,initiator dosage,polymerization time is respectively analysed on single factor. It is found that with the increase of methanol dosage and initiator dosage,the degree of polymerization of PVAc is degraded.But with the time rise, the degree of polymerization increase first and then decrease. The better process condition determined by orthogonal experiment of late alcoholysis degree of polymerizationof PVAc for 2905 and molecular weight distribution for 2.0719 are VAc=600ml、MeOH:VAc=12%、AIBN:VAc=0.025%、3h reaction time.The repetitiveness of this process is better.3. In the process of alcoholysis reaction by PVAc to prepare PVA-2486,the content of water, the usage of alkali and the time of polymerization is respectively analysed on single factor. It is found that with the increase of alkali dosage,the degree of polymerization of PVAc is increased which is opposite to effect of water dosage. But with the time rise, the degree of polymerization decrease first and then increase. The better process condition determined by orthogonal experiment for PVA2486 which has better repetitiveness is listed as follows:PVAc=50g、PVAc:MeOH=20%、NaOH:PVAc=0.6%、H2O:PVAc=14%、T=40℃、t=30min Also, the indicators of PVA-2486 prepared are completely accord with the requirement of PVA 2486 in Japan. There are little difference for two kinds of products by comparison of surface tension and dispersion properties.4. Based on Molecular design theory,—OH and—OAc in PVA can be Serialization distributed by using different ratio of polar and nonpolar solvent in alcoholysis process.The segment rate can be measured by 13CNMR,and the condition for preparing PVA with segment rate of 0.46 and excellent dispersive performance can be determined by uniform design method:PVAc=50g、NaOH:PVAc=0.6%、H2O:PVAc=14%、T=40℃、benzene 120ml.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Polymer resin and plastic > Polyvinyl alcohol
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