Semibatch Emulsion Polymerization of BA : Effect of Functional Monomers

• Main Authors: Fong-Yi Lin, 林豐儀
• Other Authors: Chorng-Shyan Chern
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/59847090717128220902

碩士 === 國立臺灣科技大學 === 化學工程研究所 === 83 === The concentration of surfactant in the initial reactor charge is the most important parameter in determining the particle size of the latex product produced in the semibatch ( BA/ functional monomers ) . The functional monomers ( acrylic acid or methacrylic acid ) incorporated into the emulsion polymer can increase the latex stability . Increasing the concentration of the functional monomers can increase the polyelectrolytes in the bluk and also can change the particle nucleation mechanism. Experimental data of the molecular weight distribution show that the aqueuous reaction plays an important role during the early stage of polymerization when the concentration of AA is high. The particle size and Zeta potential of the latex with a high level of functional monomer is more sensitive to pH .The ratio of the concentration of AA on the surface of the particles to that "buried" with in the particles was approximately 4.3:1 ，where as the ratio of MAA on the particles surface to that buried inside the particles was 2.25:1. Experimental results of the stability study show that the amount of coagulum decreases with increasing concentration of SLS in the monomer emulsion feed. Another importrant variable is the concentration of SLS in the initial reactor charge. When the concentration of AA is relatively high or low ， the amount of scrap formed during the reaction is singificant. We find for new particles produced during the monomer emulsion feed the large latex particles with various solid contents . Finally， we use the Novak theory to analyse the effect of AA on the final latex particle size . The slope of the log(df) -log(1/Ga) graph is 0.295 that is close to the theortical value of 0.333. We then change the experiment''s recipes to study the coagulation and secondary nucleation processes . The slope is decreased when we increased the ion strength or added extra SLS in the monomer emulsion feed .