Polymerization Processes

A novel route for synthesis of cross-linked polystyrene copolymer beads with tunable porosity using guar and xanthan gums from bioresources as alternative synthetic suspension stabilizers

“…The permeability limits according to the molecular size and the accessibility of reactive and catalytic sites depend on the porous structure and swelling properties of the copolymers [19]. It has been established that these properties are deeply influenced by the copolymer synthesis conditions: suspension stabilizers, crosslinking degree, porogenic agent or diluent nature, etc [20–26]. …”

Influence of the geometric factors of the experimental device used in suspension polymerization on the properties of poly(styrene‐co‐divinylbenzene) microparticles

“…[12][13][14] Therefore, it would be desirable to have available quantitative relationships between the characteristics related to the size and morphology of the microparticles obtained and the experimental conditions of the suspension polymerization used in their synthesis. In fact, as stated earlier, there is a lack of reported experimental works focused on obtaining polymeric particles smaller than 100 lm.…”

“…10,11 This kind of microparticle is usually obtained by free radical crosslinking copolymerization of styrene and divinylbenzene monomers using the suspension polymerization technique, with divinylbenzene as the crosslinker. [12][13][14] With regard to the properties of the microbeads obtained with this technique in relation to their size, it must be emphasized that their mean size and their size distribution are significant characteristics regarding their applications, and, consequently, control of these aspects is one of the most important aims of suspension polymerization technology. [12][13][14] This is because the size distribution should be as narrow as possible to facilitate the use of the product, 15 and because the optimum particle size may be different, depending on the application in which the beads are to be used.…”

“…Therefore, the design of experiments addressed to obtain a given final particle size, in the case of reactive systems such as polymerization reactions in suspension, is challenging, because it is very probable that during the intermediate and final stages of the polymerization processes, the agglomeration and deformation of the droplets/particles will vary the original liquid droplet size distribution and mask the real influence of the above experimental factors on that distribution. 14,17 However, in spite of the complexity of the processes that occur throughout the polymerization reaction, several models 12,13,15,18,19 with different degrees of complexity have been developed that attempt to take into account the effects of the geometry of the reactor, the type of mixing of reactants, and even the kinetics of polymerization on particle size. Thus, Arshady 20 has reported an empirical relationship whose aim is to represent most of the results obtained earlier by combining the values of the synthesis conditions and those of certain geometric factors of the experimental device to predict the mean size of the microparticles.…”

Rheo-mechanische Untersuchungen der Netzwerkstruktur von Elektrodenkontaktgelen und HPLC-Methode zur Bestimmung des Restmonomergehaltes

“…4). Bei der statistischen Copolymerisation von Vinyl-und Divinylmonomeren entsteht ein relativ hoher Anteil an freien Kettenenden 35) , da mit fortschreitendem Umsatz aufgrund der steigenden Lösungsviskosität die Rekombination von wachsenden Polymerradikalen eingeschränkt ist. Zudem wurde gefunden, daß die Effektivität des Vernetzers mit 1%, unabhängig vom Vernetzungsgrad, sehr niedrig ist.…”