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Polyvinyl Alcohol and Polyvinyl Acetate
Published in Abdullah Al-Mamun, Jonathan Y. Chen, Industrial Applications of Biopolymers and their Environmental Impact, 2020
VAM is manufactured through catalytic conversion reaction of acetic acid and ethylene with oxygen. Due to higher reactivity of vinyl acetate monomer, a polymerization inhibitor is required in order to control the degree of polymerization. VAM can be produced starting from ethylene, which is converted to acetic acid via acetaldehyde by two sequential oxidation steps, the first step being the famous Wacker process [50]. Another way to produce acetic acid is based on a carbonylation of methanol in the so-called Monsanto process, which is the dominant technology for the production of acetic acid today [51]. Acetic acid is then converted to VAM by addition of ethylene to acetic acid in the gas phase using heterogeneous catalysts, usually based on palladium, cadmium, gold, and its alloys [52] supported on silica structures.
Novel in-depth profile control agent based on in-situ polymeric microspheres in low permeability reservoir
Published in Journal of Dispersion Science and Technology, 2020
Jirui Zou, Xiangan Yue, Jie Dong, Minglu Shao, Liqi Wang, Jun Gu, Weijie An
ISPM emulsion was prepared by emulsion polymerization. Figure 2 shows the ISPM emulsion reaction mechanism. “Emulsified dispersion crosslinker - crosslinker polymerization nucleation - grafting of external functional monomers” method was used to prepare ISPM microspheres. The aqueous solution of AM was exogenous while DVB was introverted. Oil-soluble initiator AIBN first initiated the polymerization of DVB. After the polymerization of DVB was completed, the AM monomer in the aqueous phase was captured by the active radical on the divinylbenzene microsphere, thereby obtaining the ISPM microsphere. The addition of the polymerization inhibitor p-hydroxyanisole retarded the rate of free radical polymerization, thereby prolonging the reaction time of the polymerization reaction.