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Study of the Particles Design and Size Contorl in Styrene-Acrysic Emulsion Poltmerization

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Tutor: GeShengSong
School: Shandong University of Science and Technology
Course: Chemical processes
Keywords: Styrene-acrysic Emulsion,Emulsifier,Size control
CLC: TQ316.334
Type: Master's thesis
Year:  2011
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A serise of styrene-acrysic latexes with a size ranging from 90nm to 1.3¦Ìm perpared by emulsion polymerization. In this thesis, the test results of BT9300z Particle Sizer showed they had a narrow size distrubution. The influence factors on polystyrene-acrysic particles diameter have been investigated and discussed, such as different emulsifier, polymerization technologies, monomer concentration, the ratio of ST and BA, the functional monomer, the organic solvent and the ionic strength of electrolyte, at last we found a regular pattern of the element infect the diameter of the styrene-acrylic latex.KL-100, COPS-1, A-103, CO-436, TW20, TW80, AMPS, JRF1986 and other general surfactants were usd as emulsifier in emulsion polymerization and produced a serise of polystyrene-acrysic particles with different diameters. With KL-100 we get the largest particles and with SLS get the smallest. By comparing them we found molecular structure and molecular weight of the emulsifier have a great impact to the particles diameter, when the hydrophobic group longer, the particles diameter increased; and when the hydrophilic property of the hydrophilic group stronger, the particles diameter discreased; use the emulsifier with double bond also can get the large particles. Mixed different emulsifier, the diameter will compromised except COPS-1 and AMPS. Emulsifier¡¯s change had no significant effect on the film hardness but important to the film water resistance.Particles diameter also infected by the polymerization technologies, we get the largest particles by pre-emulsification process and the smallest by batch polymerization process. When other factors were kept constant, the particles diameter inereased with monomer conceniration, but the size distrubution wider. When the BA ratio raised, the particles diameter inereased. But when the AA ratio raised, the particles diameter discreased first and then inereased, only the ratio of the AA is 1/5 in the monomer we can get the smallest diameter. Ionic strength, organic solvent and polypolyols also can increast the particles diameter, but size distrubution became wider with its¡¯ added.With petroleum ether and acrylic acid as raw materials, we synthesis a amphiphilic polymer surfactant, then used it as emulsifier in emulsion polymerization. The results showed that the average particle size was 0.62¦Ìm, and the latex has preferable properties of the stability in latexs and films. To the emulsifier molecular, the experiments also showed that the longer the chain the easier it curly, only increase the chain length or molecular weight can not increase the particles size, the complex ralationship of emulsifier¡¯s structure and particles diameter are also still need systematic research.
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