Examinando por Materia "POLIBUTADIENOS"
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- Artículo de Publicación PeriódicaExperimental and theoretical study of the use of multifunctional initiators in the high impact polystyrene bulk process(2018-02) Berkenwald, Emilio; Laganá, María Laura; Maffi, Juan M.; Acuña, Pablo; Morales Balado, Graciela Elizabeth; Estenoz, Diana"The performance of three multifunctional peroxide initiators in a bulk high impact polystyrene (HIPS) process was experimentally and theoretically investigated. For the experimental work, a series of batch reactions was carried out, comprising the main stages of an industrial HIPS bulk process using multifunctional initiators with varying functionality and structure: DEKTP (cyclic trifunctional), PDP (cyclic bifunctional) and L331 (linear bifunctional). The theoretical work consisted of the development of a comprehensive, generic yet detailed mathematical model for bulk HIPS polymerization using multifunctional initiators. The model predicts the evolution of the main polymerization variables (including conversion, molecular weights, grafting efficiency) as well as the detailed molecular structure of the polymeric species (free polystyrene, residual polybutadiene and graft copolymer), and the melt flow index of the obtained HIPS. The model was adjusted and validated using experimental results, obtaining a good agreement between measured and predicted values. The model was used to theoretically evaluate the effect of the operating conditions on the molecular and physical characteristics of the obtained polymer. It was found that the use of multifunctional initiators leads to high polymerization rates and high molecular weights simultaneously, while promoting the grafting of styrene onto butadiene, generating a microstructure with salami-type morphologies."
- Artículo de Publicación PeriódicaMechanisms and conditions that affect phase inversion processes. The case of high-impact polystyrene(2019) Maffi, Juan M.; Casis, Natalia; Acuña, Pablo; Morales Balado, Graciela Elizabeth; Estenoz, Diana"The phase inversion during the bulk polymerization of the styrene-polybutadiene system (HIPS manufacturing process) is empirically and theoretically studied in this article. In the experimental work, a series of reactions were performed with benzoyl peroxide as initiator and at temperatures considered of industrial interest (80ºC and 90ºC), varying also the reactor stirring level. Phase inversion was determined by offline viscosity measurements and verified by scanning electron micrography in transmission mode (STEM). The rheological behavior of each reacting system was analyzed and an empirical correlation to predict its apparent viscosity from fundamental reaction parameters was derived. This was achieved successfully for bothbefore and after the phase inversion point."