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Polyelectrolyte’s Influence on the Behavior of Acrylic Emulsion

Author: ZhangHao
Tutor: XiaYuZheng
School: Beijing University of Chemical Technology
Course: Chemistry
Keywords: Emulsion polymerization behavior Polyelectrolyte Acrylate A styrene - acrylic resin
CLC: TQ316.334
Type: Master's thesis
Year: 2010
Downloads: 125
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Abstract

In the emulsion polymerization process, the polyelectrolyte may be by changing the degree of aggregation of the latex particles with the component (initiator, emulsifier and monomer) is affected by the rate of diffusion of acrylic emulsion polymerization behavior. Wherein the main factors affect the performance of the polyelectrolyte is the size and distribution of a weight average molecular weight of polyelectrolyte, the flexibility of the segment, the number of hydrophilic groups, density and distribution. Polyelectrolyte and its impact on emulsion polymerization behavior in-depth research has a great sense of acrylate emulsion polymerization mechanism further comprehensive study of the dynamic behavior and performance (viscosity, adhesion and stability). By orthogonal experimental design, the choice of in atmospheric low temperatures, as a protective gas in N2 atmosphere at 120 ℃, atmospheric semi-continuous solution polymerization process, benzoyl peroxide (BPO) as initiator, 3 - mercapto propionic acid (MPA) as a chain transfer agent, ethylene glycol monobutyl ether as a solvent, α-methyl styrene (AMS) / styrene (St), and methacrylic acid methyl ester (MMA), butyl acrylate (BA ), acrylic acid (AA) polyhydric copolymerization, was synthesized as a colorless and transparent water-soluble solid styrene - acrylate MW series, such as Styrene-acrylic A ((?) = 2880), Styrene-acrylic B ((?) = 3920), Styrene-acrylic C ((?) = 4678), Styrene-acrylic D ((?) = 7089), Styrene-acrylic E ((?) = 11039), the acid value = 230-240, and Tg = 30 -40 ℃, then by vacuum distillation and ammoniated to give a pale yellow water-soluble polymer electrolyte solution. On the basis of the polyelectrolyte, the paper focuses on varnished with acrylic emulsion (MMA / BA binary system) polymerization behavior, ie pre-emulsified semi-continuous dropping method to study polyelectrolyte (water-soluble solid styrene - acrylate resin the ammoniated solution) having a weight average molecular weight (Mw = 2500-12000), the amount (0-20%) of acrylate emulsion course, conversion rate, and the generation rate of the floc, the latex particle size and its distribution and Zeta potential and aggregation parameters. It was found that the polyelectrolyte acrylate emulsion polymerization behavior of their micellar aggregation degree, the rate of diffusion has important links. Specifically as follows: 1. By comparing a styrene - acrylic polyelectrolyte different concentrations and weight average molecular weight under the surface tension and the conductivity value was found polyelectrolyte CMC value of only 0.2%, the surface tension in the vicinity of 45N / m, the estimated HLB = 6-7, and its diffusion rate decreased with the increase in weight average molecular weight and the concentration of micelle degree of aggregation with the weight average molecular weight and the increase in the concentration of higher. By blank emulsion particle size - time and particle size distribution - time curve analysis can be found using the semi-continuous dropping of pre-emulsification processes and higher levels of MMA acrylate emulsion polymerization exist homogeneous nucleation and micelle nucleation and the the micellar nucleation to homogeneous nucleation process of transformation. 3 diameter through Styrene-acrylicA - time and conversion rate - time curve analysis can be seen, when the concentration is low, the system because of its high rate of diffusion of its homogeneous nucleation probability increased, the particle diameter is lower and the conversion higher; When the concentration is higher, the system because of its high micelle gathering degree it micelles to increase the probability of nucleation and the particle diameter is higher and lower conversion rates. 4. Polyelectrolyte weight average molecular weight of the latex particles with the emulsion conversion rate value impact analysis, can be seen, when the weight average molecular weight is low, the system because of the high diffusion rate of their probability of homogeneous nucleation Increased; while when the weight average molecular weight is high, the system because of its high micelle gathering degree it micelles to increase the probability of nucleation. 5 flocs generation rate increase at first and then the downward trend, but the overall basically stable at a lower value; Styrene-acrylic B and C values ??were bilinear transition trend; Styrene Styrene-acrylic A value was The value of the of-acrylic D and E, was the first drop after increasing trend. Zeta potential impact Styrene-acrylic A, B, C, and E values ??increased first and then decreased; Styrene-acrylic D values ??were generally decreased.

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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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