نتایج جستجو برای ' polymerization '

Generation of free radical species is an essential element of all free-radical polymerization reactions. A lot of organic molecules are stable at moderate and elevated temperatures. Therefore, in some reactions the addition of stable free radical which shows very little or almost no tendency in self-combination is of great importance, as free radical species are aimed to initiate reactant molecules in a specific reaction. The radical species differ in a wide range from organic to inorganic chemi...

Polyamide 6 (PA6)/MMT nanocomposites prepared by in-situ polymerization and melt compounding methods were used in this study. The organoclay PA6 nanocomposites were then injection molded by conventional and microcellular methods. Carbon dioxide was used as the blowing agent. The effect of injection screw speed, organoclay content, and preparation methods on the mechanical/thermal properties was investigated. The results showed that the screw speed of the injection had major effect on the mechani...

In this work, we used grinard reagent to prepare dithiocarboxylic acid. Then as first option, oxidation with dimethyl sulfoxide (DMSO) to diphenyldithioperoxyanhydride and its derivate was carried out. The formation of dithoesters is possible when the coupled compounds (disulfides) are allow to react with initiators such as 4,4- azobis(4-cyano pentanoic acid). The synthesized RAFT agent were identified by fourier-transform infrared (FTIR) and nuclear magnetic resonance spectroscopy (NMR).

Using extruder as batch reactors, for processes such as polymerization, polymer adjustment or polymeric alloy adaptation is among the technologies which are getting more favorable day to day and they can challenge traditional ways through their economical efficiency. In the present paper, technical advantages, disadvantages and characteristics of reactor extruder and the state of flow mechanism performance in extruder have been investigated and studied, and the effective parameters on the proces...

 To improve both the mechanical and thermal properties of kaolin/polypropylene (PP) composites, kaolin was modified by using 3-(trimethoxysilyl) propylmethacrylate (YDH-570) as a coupling agent to form polymerizable particle. Styrene was radically polymerized through the immobilized vinyl using benzoyl peroxide (BPO) as an initiator. Fourier transform-infrared (FTIR) spectroscopy, particle size distribution, X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA) well demonstrated tha...

 This paper presents a novel and facile route to preparation of highly uniform polymeric microspheres through a quiescent polymerization with the reactor standing still without any stirring. Using one single monomer, isophorone diisocyanate (IPDI), highly uniform polyurea microspheres are achieved with high yield via precipitation polymerization of IPDI with water in water–acetone mixed solvent. Full conversion of IPDI to polymer is readily achieved thanks to the step polymerization m...

 Poly(4-vinylpyridine) (P-4VP) brushes of different lengths were grafted onto halloysite nanotubes (HNTs) by surface-initiated atom transfer radical polymerization (SI-ATRP) and methyltrioxorhenium(VII) (CH3ReO3, MTO) was immobilized onto HNTs through P-4VP brushes to catalyze epoxidation of soybean oil. 2-Bromoisobutyryl bromine was chosen as the initiator of SI-ATRP and anchored by reacting with hydroxyl groups of HNTs. To reduce the effect of 4-vinylpyridine on the initiator, Me6tren as ...

 Ultrasonic transmission is a simple, non-destructive method to characterize turbid systems like e.g. emulsions or polymer dispersion. Here we use this technique for in-line monitoring of the miniemulsion polymerization of styrene. Either the ultrasound attenuation or the velocity signal provides a fingerprint characterizing the reaction process. During the reaction process the sound velocity increases by about 150 m/s and the attenuation coefficient α changes by more t...

 A synergetic dispersion strategy was developed for the preparation of the well-defined magnetic Fe3O4@graphene oxide/polystyrene (Fe3O4@GO/PS) tri-component nanocomposite by the facile one-pot in situ radical bulk polymerization of styrene in the presence of the Fe3O4 nanoparticles modified graphene oxide (Fe3O4@GO) magnetic hybrid with oleic acid (OA) as surface modifier. Compared with the tri-component nanocomposite prepared with the graphene oxide (GO) and Fe3O4 nanoparticles ...

 The preparation process and optimization condition for synthesize polyamide microparticles directly onto cellulosic surface carried out by interfacial polymerization were investigated by a design screening method. The influences of organic solvent choice, the impregnation time, the monomer amount as well as the temperature bath and the reaction time were studied. Based on the encapsulation yield percentage (polymerization yield), the optimum conditions for microparticles preparation were (...