Study On The Synthesis, Properties And Application Of Cross-linked Polyvinyl Pyrrolidone

Polyvinyl pyrrolidone is a kind of non-ionic water-soluble polymer. It is the most characteristic fine chemical in the N-vinyl amido polymers that applied widely. N-vinylpyrrolidone is useless in the industry field. The homopolymers and copolymers of N-vinylpyrrolidone, obtained by homopolymerization of the monomer and copolymerization of NVP and other vinyl monomers, have different properties to meet for diverse requirements in various application areas. Cross-linked PVP can be obtained by cross-linking of linear PVP. And more densely cross-linked products are obtained by precipitation polymerization of N-vinyl pyrrolidone with a cross-linking agent.The main contributions of the dissertation are as follows:1, Main physical and chemical properties and synthesis of N-vinylpyrrolidone are introduced in this dissertation. The research and developement of the three types of PVP including homopolymers, copolymers and cross-linked polymers of PVP are discussed. We will mainly introduce the cross-linked PVP in detail.2, Cross-linked PVP were synthesized by suspension polymerization and popcorn polymerization of N-vinyl pyrrolidone respectively in this dissertation. We can get different products when we changed the kind of crosslinking and reaction atmosphere.3, The chemical structure, thermal property and surface appearance of cross-linked PVP were characterized by means of infrared spectrum, differential scanning calorimetry and scanning electron microscopy etc. 4, On the base of literatures we analyse the properties of cross-linked PVP under the different reactive conditions in theory. Effects of temperature, the content of initiator, dispersing agent and crosslinking agent and reaction atmosphere on the yield, the swellable power and adsorption properties of cross-linked PVP were discussed.The results showed that cross-linked PVP prepared by suspension polymerization had the gel volume of 5-50 mL/g. The adsorption quantity of these cross-linked PVP for tannin and salicylic acid could reach 80 mg/g and 169 mg/g. The yields were above 90%. However, cross-linked PVP prepared by popcorn polymerization had the gel volume of 5-8 mL/g. The adsorption quantity of the cross-linked PVP for tannin and salicylic acid could reach 103 mg/g and 194mg/g.The yields were 70-80%. DSC studies showed the glass transition temperature of cross-linked PVP formed by suspension and popcorn polymerization was much higher than that of linear PVP and Tg of cross-linked PVP increased with increasing the crosslinking agent content. SEM photographs showed popcorn PVP presented itself as loose particles with large surface area and cross-linked PVP prepared by suspension polymerization were compact particles. In order to get different product particles we can change the kind and content of crosslinking agent. When NMBA is used as the crosslinker the product has a lower gel volume than using DVB. The adsorption quantity of the cross-linked PVP for beer and beverage were good.