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Monomer Type (monomer + type)
Selected AbstractsEffect of the carboxylic acid monomer type on the emulsifier-free emulsion copolymerization of styrene and butadieneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Mahdi Abdollahi Abstract Carboxylated styrene,butadiene rubber latexes were prepared through the emulsifier-free emulsion copolymerization of styrene and butadiene with various carboxylic acid monomers. The effects of various carboxylic acid monomers on the particle formation process were investigated. The type of carboxylic acid monomer strongly affected the particle nucleation. The number of particles and thus the polymerization rate increased with the increasing hydrophobicity of the carboxylic acid monomers. There was a significant difference in the polymerization rate per particle. The results showed that particle nucleation and growth were dependent on the hydrophilic nature of the carboxylic acid monomers. The average particle diameter of the carboxylated styrene,butadiene rubber latexes in the dry state was obtained through some calculations using direct measurements of the average particle diameter in the monomer-swollen state by a dynamic light scattering technique. Several parameters, such as the polymerization rate, number of latex particles per unit of volume of the aqueous phase, and polymerization rate per particle, were calculated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Emulsion polymerization of divinyl monomers stabilized by sodium dodecyl sulfate and bis(2-ethylhexyl)sulfosuccinate sodium saltJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2002Barbara Gawdzik Abstract The emulsion polymerization of divinyl monomers is investigated. Emulsions were obtained in the presence of sodium dodecyl sulfate and bis(2-ethylhexyl)sulfosuccinate sodium salt as surfactants. The influence of monomer type and kind of surfactant on the particle size distribution is studied. The porous structure of the broken emulsions is also determined. The results indicate that the diameter of nanospheres obtained from two divinyl monomers are significantly larger than those obtained from polystyrene. Aggregation of the particles and the pore-forming diluent added to the emulsion are responsible for the existence of pores. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3967,3973, 2002 [source] Ethylene and Propylene Polymerization Using In Situ Supported Me2Si(Ind)2ZrCl2 Catalyst: Experimental and Theoretical StudyMACROMOLECULAR MATERIALS & ENGINEERING, Issue 3 2006Fernando C. Franceschini Abstract Summary: Me2Si(Ind)2ZrCl2 was in situ immobilized onto SMAO and used for ethylene and propylene polymerization in the presence of TEA or TIBA as cocatalyst. The catalytic system Me2Si(Ind)2ZrCl2/SMAO exhibited different behavior depending on the amount and nature of the alkylaluminum employed and on the monomer type. The catalyst activity was nearly 0.4 kg polymer,·,g cat,1,·,h,1 with both cocatalysts for propylene polymerization. Similar activities were observed for ethylene polymerization in the presence of TIBA. When ethylene was polymerized using TEA at an Al/Zr molar ratio of 250, the activity was 10 times higher. Polyethylenes made by in situ supported or homogeneous catalyst systems had practically the same melting point (Tm). On the other hand, poly(propylenes) made using in situ supported catalyst systems had a slightly lower Tm than poly(propylenes) made using homogeneous catalyst systems. The nature and amount of the alkylaluminum also influenced the molar mass. The poly(propylene) molar mass was higher when TIBA was the cocatalyst. The opposite behavior was observed for the polyethylenes. Concerning the alkylaluminum concentration, the molar mass of the polymers decreased as the amount of TEA increased. In the presence of TIBA, the polyethylene's molar mass was almost the same, independent of the alkylaluminum concentration, and the poly(propylene) molar mass increased with increasing amounts of cocatalyst. The deconvolution of the GPC curves showed 2 peaks for the homogeneous system and 3 peaks for the heterogeneous in situ supported system. The only exception was observed when TEA was used at an Al/Zr molar ratio of 500, where the best fit was obtained with 2 peaks. Based on the GPC deconvolution results and on the theoretical modeling, a proposal for the active site structure was made. Molar mass distribution deconvolution of polyethylene prepared with the system Me2Si(Ind)2ZrCl2/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst. [source] Effects of hydrophilic monomer types on poly(styrene-acrylate)/montmorillonite nanocomposites made by in-site emulsion polymerization,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2009Fa-Ai Zhang Abstract Organic modified montmorillonite (OMMT) was made of pristine montmorillonite (MMT) treated with cetyl trimethylammonium bromide (CTAB). Two kinds of nanocomposites, poly(styrene-acrylate)/MMT (P(S-A)/MMT) and poly (styrene-acrylate)/OMMT (P(S-A)/OMMT) were prepared from styrene (St), hydrophilic acrylate monomer, and MMT (or OMMT) by in-site emulsion polymerization. Effects of different monomers, , -hydroxyethyl methacrylate (HEMA), acrylic acid (AA), methacryclic acid (MAA) on the thermal stability of the two nanocomposites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The structures of the nanocomposites were characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD). The morphology of the nanocomposite was observed by transmission electron microscope (TEM). The results showed that the thermal stabilities of the two composites were enhanced by the addition of HEMA, AA, or MAA. The P(S-A)/OMMT nanocomposite showed higher thermal stability than that of the P(S-A)/MMT nanocomposite. In particular, HEMA improved the thermal stability of the P(S-A)/OMMT nanocomposite, which is more efficient than methacrylic acid (MA) and AA. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||