SynopsisSemicontinuous emulsion copolymerization of styrene and butyl acrylate with a constant rate of feed of monomer emulsion was investigated. The integral composition of the copolymer at the end of the feeding was different from the feed composition, and the difference was proportional to the monomer feeding rate. The closer the feed composition was to the composition at the azeotropic point, the lower was the sensitivity of the system to the feeding rate. At low feeding rates, the copolymerization proceeded at conversions of about 90-95%, and the composition of the copolymer was practically equal to that of the monomer feed. The reactivity ratios determined under these conditions were probably influenced by diffusion inside the growing polymermonomer particles.
SynopsisSemicontinuous emulsion copolymerization of acrylonitrile (MI), butyl acrylate (Md, and styrene (M:l) was investigated. The copolymerization proceeded under the conditions used with a high degree of conversion, whereby a stationary state characterized by a constant monomer mixture composition and a constant composition of the arising copolymer was achieved. From the analytically estimated free monomers and arising copolymer compositions, the reactivity ratios for the pair ANDA r 1 2 = 0.71, r21 = 1.17 and for the pair AN/Sty r13 = 0.06, r31 = 0.28 were calculated. The applicability of the reactivity ratios found was verified also for the ternary system acrylonitrilehutyl acrylatel styrene.
EXPERIMENTALCopolymerizations were carried out in a 2-liter steel reactor at 70°C in a nitrogene atmosphere from the following materials:
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