the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

The slurry polymerization of ethylene was studied by employing a (TiCl4/Mg(OEt)2/TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, Mv, were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and Mv were achieved at 60 °C. The concentrat...

poly(vinyl acetate) is synthesized via solution polymerization, and then it is converted to poly(vinyl alcohol) by alkaline alcoholysis. the aim of the work study was to investigate statistically the  influence of reaction variables in vinyl acetate polymerization, the conversion of this monomer to polymer, degree of branching of acetyl group in poly(vinyl acetate), as well as the molecular wei...

in the current work, ethylene polymerization was investigated from a mathematical modeling point of view. the initiation (activation), propagation, termination, and deactivation reactions were taken into account and the relevant equations used in the modeling were obtained from the elementary reactions. some assumptions including neglecting the transfer and deactivation reactions were considere...

BACKGROUND Actin filaments polymerize in vivo primarily from their fast-growing barbed ends. In cells and extracts, GTPgammaS and Rho-family GTPases, including Cdc42, stimulate barbed-end actin polymerization; however, the mechanism responsible for the initiation of polymerization is unknown. There are three formal possibilities for how free barbed ends may be generated in response to cellular ...

Microtubule inhibitors can be classified into two categories: 1) those which inhibit the polymerization-dependent GTPase activity of phosphocellulose-purified tubulin, but induce a significant polymerization-independent GTPase activity (e.g. colchicine, griseofulvine, daunorubicine); 2) those which inhibit the GTPase activity associated with tubulin polymerization and that induced by inhibitors...

this study aims at exploring an effective route in the in situ graft polymerization of aniline from fe3o4 nanoparticles. to this goal, fe3o4 magnetic nanoparticles were prepared by coprecipitation method using ammonia solution as the precipitating agent, and were characterized by fourier transform infrared (ft-ir) spectroscopy, x-ray diffraction (xrd) and transmission electron microscopy (tem)....

styrene polymerization through frp and atrp methods was carried out at 110oc, while in-depth studies were performed by monte carlo simulation.the changes in monomer conversion, initiator concentration, average molecular weight, and polydispersity index were computed over the course of the polymerization. as the results indicate, compared to atrp, the frp reaches higher conversion in a similar r...

We report the first use of a polymerization-based ELISA substrate solution employing enzymatically mediated radical polymerization as a dual-mode amplification strategy. Enzymes are selectively coupled to surfaces to generate radicals that subsequently lead to polymerization-based amplification (PBA) and biodetection. Sensitivity and amplification of the polymerization-based detection system we...

OBJECTIVE To examine the amount of change in color and color parameters of a composite resin (Filtek P60) polymerized by five different polymerization methods. METHODS A Teflon mold (6mm in diameter, 2mm in height) was used to prepare the composite resin discs (n=10). G1: Polymerization with inlay oven; G2: Polymerization with HQTH and autoclave; G3: Polymerization with LED and autoclave; G4:...