Influence Of Monomer Research Articles

Studies on the Influence of Monomers on the Performance Properties of Epoxy Acrylate Resin

Twelve blend samples were prepared by physical mixing of epoxy acrylate resins with various monomers viz. ethoxylated phenol monoacrylate (EOPA), tripropylene glycol diacrylate (TPGDA) and trimethylol propane tri acrylate(TMPTA), having weight ratio of epoxy acrylate resin and monomers are 50:50, 60:40, 70:30, 80:20. These samples were cured under UV radiation using 5% photo initiator by weight. These blends were evaluated for mechanical, chemical & thermal properties. It was found that the sample having mono & tri functional monomers shows better properties than the samples having di functional monomer.

Synthesis of highly reactive polyisobutylenes using solvent‐ligated manganese(II) complexes as catalysts

AbstractManganese complexes with benzonitrile ligands were synthesized, characterized, and applied for the preparation of the isobutylene polymerization. Low and medium molecular weight polyisobutylenes containing high amount of exo‐type double bond end groups (70–80%) were successfully prepared using these manganese(II) complexes as catalysts at room temperature. The influence of monomer and catalyst concentration was intensively analyzed for achieving high monomer conversion and high exo double bond content of the products. Details on end group distribution in the products and development of the exo‐type end group content with reaction time were evaluated by 1H NMR. The catalysts are also active for the homopolymerization of styrene and the copolymerization of isobutylene and styrene. The highly reactive polyisobutylene products obtained by these manganese complexes show features similar to products obtained by conventional cationic polymerization, but the polymerization characteristics clearly deviate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5636–5648, 2007

Facile synthesis and characterization of hyperbranched poly(ether amide)s generated from Michael addition polymerization of in situ created AB2 monomers

AbstractA new straightforward strategy for synthesis of novel hyperbranched poly (ether amide)s from readily available monomers has been developed. By optimizing the reaction conditions, the AB2‐type monomers were formed dominantly during the initial reaction stage. Without any purification, the AB2 intermediate was subjected to further polymerization in the presence (or absence) of an initiator, to prepare the hyperbranched polymer‐bearing multihydroxyl end‐groups. The influence of monomer, initiator, and solvent on polymerization and the molecular weight (MW) of the resultant polymers was studied thoroughly. The MALDI–TOF MS of the polymers indicated that the polymerization proceeded in the proposed way. Analyses of 1H NMR and 13C NMR spectra revealed the branched structures of the polymers obtained. These polymers exhibit high‐moderate MWs and broad MW distributions determined by gel permeation chromatography (GPC) in combination with triple detectors, including refractive index, light scattering, and viscosity detectors. In addition, the examination of the solution behavior of these polymers showed that the values of intrinsic viscosity [η] and the Mark–Houwink exponent α were remarkably lower compared with their linear analogs, because of their branched nature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4309–4321, 2007

The grafting of maleic anhydride onto natural rubber

Graft copolymers of natural rubber and maleic anhydride (NR -g-MA) or maleated natural rubber (MNR) were synthesized in a toluene solution. Benzoyl peroxide (BPO) was used to initiate the free radical graft copolymerization. Influence of monomer and initiator concentrations together with effect of the reaction temperature and reaction time were investigated. Quantities of the grafted anhydride (MA) were determined by titration of the carboxylic acid functions derived from the anhydride functions. Estimation of the grafted MA level was also performed using IR absorbance ratio of the peaks at 1780–1784 cm −1 plus 1854 cm −1 to 835 cm −1. We found that quantities of the grafted MA on NR molecules increase with increasing monomer and initiator concentrations. The increase in reaction time and reaction temperature also causes increasing levels of the grafted MA. We also found that the glass transition temperature of the MNR was higher than that of the pure NR. Furthermore, the T g values increase with increasing the monomer concentration used in the graft copolymerization.

Deviation from Single-Site Behavior in Zirconocene/MAO Catalyst Systems, 1. Influence of Monomer, Catalyst, and Cocatalyst Concentration

The polymerization of 1-hexene with the catalyst systems Cp2ZrCl2/MAO and Me2SiInd2ZrCl2/MAO is investigated in order to elucidate the nature of the active species in zirconocene/MAO catalyzed polymerizations. Varying monomer concentration and monomer conversion does not result in any unexpected behavior. However, changing catalyst and cocatalyst concentration leads to broadened, or even bimodal, molecular weight distributions under certain reaction conditions. These results may be interpreted in terms of a coexistence of two active species with different rates of propagation and of termination.

The Influence of Monomers upon Microemulsions with Short Chain Cosurfactant

Several monomers (i.e., acrylonitrile (ACN), ethyl acrylate (EtA), acrylate of 2 ethylhexyl (EHA), butyl acrylate (BuA), vinyl acetate (VAc), methyl methacrylate (MMA) and styrene (St)) were investigated in order to study their capacities to form microemulsions. The surfactant was nonyl phenol ethoxylate with 25 moles ethylene oxide and ethanol was used as the cosurfactant. The phase diagrams prove that the capacity for microemulsion formation varies in the following sequence: ACN = EtA > VAc > BuA > MMA > St > EHA. Conductometric and refractometric studies allowed us to evidence the formation of microemulsions with W/O, bicontinuous or O/W structure. Fluorescence studies give interesting informations on the stabilization capacity of the monomers dispersed by interaction with hydrophobic chain of the cosurfactant. H-NMR studies suggest that the monomers in microemulsions lie in regions with various polarities as function of their chemical nature. In polymerization initiated with benzoyl peroxide the minimum conversions were obtained in zones of composition where the initial microemulsions possess a bicontinuous microstructure. The reactions of degradative transfer of the increasing macroradicals account for these conversion modifications. For initiation with ammonium persulphate, its rate of decomposition depends on its ability to displace the proton bonded to the substituted vinylic carbon of the monomer. The productivity of this initiator varies within the sequence MMA > EtA > BuA > St > ACN > VAc. The consumption of the initiator, as induced by the monomer, depends on its chemical nature and on the solubilization site of the microemulsions.

Synthesis and characterization of a silyl substituted bis(indenyl) zirconium dichloride and comparison of its olefin polymerization behavior to a siloxy substituted analogue

The synthesis and characterization of rac-[ethylenebis(1-(tert-butyldimethylsilyl)-3-indenyl)]zirconium dichloride (3) is reported. The silyl substituted 3/MAO was compared to its siloxy substituted analogue (4) in ethylene homo- and in ethylene-1-hexene copolymerizations to elucidate the effect of the heteroatom on polymerization performance. The influence of monomer and cocatalyst concentration and the polymerization temperature was investigated. The oxygen between the indenyl ligand and the bulky tert-butyldimethylsilyl group in the siloxy substituted 4/MAO was found to have a positive influence on polymerization activity and copolymerization performance. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 127–133, 2001

Influence of monomer and catalyst concentration on RF and carbon aerogel structure

Structure and density of organic RF (resorcinol formaldehyde) aerogels and pyrolized RF aerogels (carbon aerogels) can be modified upon variation of the resorcinol to catalyst (RC) ratio and by varying the mass ratio of the reactants resorcinol and formaldehyde in the sol. Here, series of RF and carbon aerogels have been produced with RC 200, 500 and 1500, each covering a wide density range. All samples were investigated using small angle X-ray scattering (SAXS), N 2 and CO 2 adsorption. The creation of a huge amount of microporosity due to pyrolysis was observed and investigated by CO 2 adsorption. SAXS scattering curves exhibit interesting structural changes. These investigation were accompanied by sound velocity measurements to obtain the elastic modulus.

The influence of monomer and polymer properties on the removal of organic vehicle from ceramic and metal moldings

This paper describes the effects of monomer and polymer properties on the competition between degradation of organic vehicle and transport of degradation products in ceramic moldings during pyrolysis. An experimentally tested model is studied systematically for ranges of material and process parameters characteristic of known polymers and their degradation products. The work highlights the properties having the greatest influence on the successful removal of organic vehicle from molded ceramics. The polymer properties controlling the diffusion constant are linked to the temperature dependence of viscosity of the molten suspension. Enthalpy of vaporization of the organic vehicle and the activation energy for the diffusion coefficient have a commanding influence on the critical heating rate for avoidance of defects. Preliminary guidelines emerge for the design of polymers for plastic forming of ceramic suspensions.

Surface modification of polymers—III. Photo-initiated grafting of water soluble vinyl monomers and influence on fibrinogen adsorption

Grafting of water soluble vinyl monomers in the superficial layer of styrene-(ethylene-cobutene)-styrene (SEBS) triblock copolymer has been performed by two different methods taking into account diffusion phenomena. The methods consist in successive or simultaneous diffusion of benzophenone and monomer into the film followed by u.v. irradiation of the film. Grafting of methacrylic acid and N-vinyl-2-pyrrolidone occurs by both methods, as detected by i.r. transmission spectroscopy. However, only grafting after simultaneous diffusion results in a change of surface properties, characterized by contact angle measurements, 125I human fibrinogen adsorption studies and ATR i.r. spectroscopy. Diffusion of monomer and photo-initiator into SEBS, kinetics of grafting and influence of monomer and benzophenone concentration have been studied.

Influence of Monomer and Initiator Concentrations on the Simultaneous Grafting of Several Monomers onto Insoluble Collagen

Abstract Simultaneous grafting of 2-hydroxyethyl methacrylate and methyl methacrylate (3:1 and 3:2 mole ratios) onto insoluble collagen with ceric ammonium nitrate as initiator was attempted with a view to optimizing conditions for the preparation of hydrogels. The influence of monomer and initiator concentrations on the grafting reactions was investigated. The grafting results are discussed in the light of grafting efficiency and percentage of grafting. They were found to be lower when the 3:1 mole ratio of monomers was used.

Polymerization of acenaphthylene by BF 3-Et 2O

The polymerization of acenaphthylene initiated by BF 3-Et 2O has been studied in ethylene dichloride and in methylene dichloride. The influence of monomer and catalyst concentrations, as well as that of the temperature, on the polymerization rate and on the polymer molecular weight has been investigated. The polymerizations are internally of second order with respect to the monomer, at least for conversions below about 50 %. Reaction order with respect to the catalyst is 1·5 and the overall activation energy is about 20 kcal/mole. The application of a d.c. field (0·1 to 1·0 kV/cm) appreciably enhances the polymerization rate and reduces the order with respect to the catalyst to 1 0. Also the molecular weights are increased by the application of the electric field.