Application of a compositional rotatable plan in modeling the propylene content in a vinyl chloride/propylene copolymer
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Application of a compositional rotatable plan in modeling the propylene content in a vinyl chloride/propylene copolymer Marzena Wiener1 · Andrzej Gawdzik1 Received: 15 August 2019 / Revised: 19 October 2019 / Accepted: 28 October 2019 © The Author(s) 2019
Abstract Using a fractional rotatable plan, the effect of five input parameters of the conduct of the copolymerization process on the amount of propylene built into the copolymer, obtained as a result of free radical suspension copolymerization of vinyl chloride with propylene in a batch suspension polymerization reactor, was analyzed. Using the results obtained, the analysis of variance was carried out and the influence of particular factors and their interactions on the product properties was determined. Thus, it was determined that the greatest influence on the amount of the incorpo‑ rated propylene in the copolymer is exerted by the amount of propylene introduced into the system, while the effect of the initiator on the product properties analyzed was found to be negligible. A mathematical model was also made, and then it was improved through the use of stepwise regression and verification with the results of laboratory experiments. The adequacy of the achieved model was confirmed using the Fisher–Snedecor test. It was obtained the conformity of the constructed model with the analysis of the influence of particular factors on the propylene content in the copolymer.
Introduction The polymerization of vinyl chloride in suspension results in a high purity prod‑ uct and is one of the most frequently used methods of polymer production. It is carried out in autoclaves lined with clad steel or acid resistant steel and equipped with a propeller stirrer and a heating and cooling shell. The polymerization pro‑ cess is carried out in an aqueous medium, which allows maintaining a strictly defined temperature. Too high a temperature can lead to the abstraction of hydro‑ gen chloride and the transfer of the kinetic chain to the polymer. In an aqueous
* Marzena Wiener [email protected] 1
Institute of Technical Sciences, University of Opole, Dmowskiego 7‑9, 46‑365 Opole, Poland
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Polymer Bulletin
medium, a water insoluble monomer and suspension stabilizer are dispersed. Pol‑ yvinyl alcohol, methyl cellulose and gelatin are used as stabilizers. Modifiers of polymer properties, pH regulators and initiators are also introduced into the aque‑ ous phase. The polymerization time, morphology and properties of the product are influenced by the type and number of initiators used. Organic peroxides and nitrogen compounds are most often used as initiators in suspension polymeriza‑ tion. Depending on the type of polymer obtained, the maximum polymerization pressure may range from 0.5 to 1.4 MPa, while the polymerization temperature usually remains within the range of 52–63 °C. The completion of the polymeriza‑ tion process is determined by the achievement of the assumed pressure drop to the level of about 0.35–0.2 MPa. After degassing of the unreact
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