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Water Resistance of Polyvinyl Acetate Emulsion

Author: LiuHaiYing
Tutor: GuJiYou
School: Northeast Forestry University
Course: Wood Science and Technology
Keywords: Vinyl acetate Emulsion Water resistance Modified
CLC: TQ316.334
Type: PhD thesis
Year: 2008
Downloads: 512
Quote: 1
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Abstract


In the Summary of the emulsion polymerization techniques, polyvinyl acetate emulsion and polyvinyl acetate emulsion water resistance on the basis of the method of copolymerizing with a carboxyl functional monomer, from the kind of the carboxylic acid monomer concentration, adding method and neutralization degree angle of view, the system of the carboxylic acid in a large water-soluble vinyl acetate copolymer systems emulsion stability, particle size and the viscosity and water resistance of the impact of the single component, synthesis of the water resistance improved vinyl acetate / Veova10 copolymerizable emulsion. Zeta potential analyzer, conductometric titration, laser particle size analyzer, DMA, DSC, SEM, rheometer and other means from the interaction of the Zeta potential, surface carboxyl density, carboxyl and emulsion components, carboxylic acid modified film The mechanical properties, the existence of the state of the water, particle size distribution, rheological properties and microstructure of exploration the carboxyl mechanism to improve the water resistance of the emulsion. The results show that: the surface carries a negative charge of the carboxyl-modified latex particles of the emulsion, adding the carboxyl monomer, the carboxyl moieties distributed in the surface of the latex particles, emulsion Zeta potential is increased, the emulsion stability enhancements. SEM results show that the the emulsion microstructure after the carboxylic acid-modified good dispersion state, the moderate surface carboxyl density and the amount of ionized carboxyl is effective to improve the wet strength of the emulsion. From the DMA, DSC and rheological test result: the acid is added after the emulsion film modulus increased under certain conditions, the emulsion at -42.6 ℃ ~ -50.1 ℃ bound water may freeze freezing peak appears, and PVAc and VAC / Veova10 unmodified emulsion compared Onset of the melting peak value reduced, the water resistance is preferably an emulsion of the emulsion in the low shear rate maximum viscosity when the shear rate is smaller. A suitable particle size and particle size distribution narrow emulsion of water and better performance. Consolidated results of the above analysis, the preliminary draw a carboxyl group to improve the mechanism of emulsion water as follows: When the participation of a small amount of carboxy functional monomer is copolymerized, a certain amount of carboxyl group and ionized carboxyl group located on the surface of the latex particles, a carboxyl group, and polyvinyl-hydroxy Since hydrogen role enhanced interaction, changing the state of the presence of free water, there may freeze the combination of water and polyvinyl alcohol combined, can be \The interaction between the carboxyl and hydroxyl group on the polyvinyl alcohol, so that the emulsion the Foreign Secretary entangled structure hair the cow changed, to enhance the fluidity of the emulsion, to improve the water resistance of the emulsion. Between the carboxyl group and the emulsion hydroxy the pseudo crosslinked phenomenon, to improve the modulus of the film itself, and to increase the densification of the film, to improve the emulsion water resistance. Due carboxy play into the nucleus, and changing the emulsion particle size and distribution a suitable emulsion particle diameter and a narrow distribution of particle size, can improve the penetration capacity of the substrate, the utilization of the emulsion increases, the emulsion water is improved . In situ polymerization, the addition of inorganic nanoparticles SiO 2 synthetic water resistance increased inorganic / organic hybrid emulsion using SEM, DMA, DSC, laser particle size analyzer, rheometer testing means, from the microscopic The morphology, the state of water in the system, rheological properties, film mechanical properties and other aspects characterize the performance of the emulsion. The results show that: by the sonication SiO 2 particles added to the emulsion in a good dispersion state of the latex particles, improve the water resistance of the emulsion. Add SiO 2 after, the modulus of the film is increased, the glass transition temperature, water resistance of the emulsion a shear rate corresponding to the maximum viscosity at low shear rate under the emulsion, emulsion bound water may freeze freezing peak does not appear to change the starting position of the melting peak of the free water the speculated Add SiO 2 change the state of presence of the free water in the system, in this regard differs from the carboxylic acid The modified emulsion. Synthesized emulsifier modified a with a carboxyl group-containing polymer P (VAc / AA), emulsifying agents and used in vinyl acetate emulsion, as compared with conventional emulsifying system of the OP-10, and SDS composite emulsifier, the film of Water absorption decreases. Systems studied SVS HAPS HPMAS,, DNS-86 four kinds of reactive emulsifiers and composite emulsifier DNS-628 polyvinyl acetate emulsion polymerization, results showed that: DNS-86 as emulsifier pre-emulsified process, the DNS-628 emulsifier semi-continuous seed emulsion polymerization process can be synthesized stable emulsion, and open up new avenues for the synthesis of polyvinyl acetate emulsion.

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CLC: > Industrial Technology > Chemical Industry > Molecular compound Industries ( polymer industry ) > Production process > Polymerization process. > By method of sub- > Emulsion polymerization
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