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Vinyl acetate molecular weight-conversion

The intrinsic viscosities and molecular weights of poly(vinyl acetate), poly(vinyl trideuteroacetate), and poly(trideutero-vinyl acetate) at three conversions. [Pg.458]

In this synthesis, the reactivity of monomers M decreases in the classic order methyl acrylate > MMA acrylonitrile vinyl acetate > Sty, and DPn values increase linearly with the monomer conversion. Moreover, molecular weights range from 9000 (styrene) to 70000 (methyl acrylate) and the yields are quite high after only 3 h (ca. 90%) [230,231]. In addition, the authors observed that the initial value of DPn decreases with increase in the concentration of xanthogen disulfide [TX], an observation in agreement with the following kinetic equation ... [Pg.128]

Continuons emulsion polymerization is one of the few chemical processes in which major design considerations require the use of dynamic or unsteady-state models of the process. This need arises because of important problems associated with sustained oscillations or limit cycles in conversion, particle number and size, and molecular weight. These oscillations can occur in almost all commercial continuous emulsion polymerization processes such as styrene (Brooks et cl., 1978), styrene-butadiene and vinyl acetate (Greene et cl., 1976 Kiparissides et cl., 1980a), methyl methacrylate, and chloropene. In addition to the undesirable variations in the polymer and particle properties that will occur, these oscillations can lead to emulsifier concentrations too low to cover adequately the polymer particles, with the result that excessive agglomeration and fouling can occur. Furthermore, excursions to high conversions in polymer like vinyl acetate... [Pg.339]

The dynamic model developed by Kiparissides et al M,2] and subsequently modified by Chiang and Thompson [ J] can predict the conversion, number of particles, particle diameters, etc., for the continuous emulsion polymerization of vinyl acetate. In this paper, the model is extended to predict molecular weight averages and long chain branching as well. [Pg.210]

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