Synthesis, Characterization and Reactivity Ratios of Phenylethyl Acrylate/Methacrylate Copolymers

2-Phenylethyl acrylate (PEA) and 2-Phenylethyl methacrylate (PEMA) were synthesized by reacting 2-Phenyl ethanol with acryloyl and methacryloyl chloride respectively. Homopolymers and copolymers were prepared by free radical polymerization technique using benzoylperoxide as initiator. Copolymers of PEA and PEMA with methyl acrylate (MA) and N-vinyl pyrollidone (NVP) of different compositions were prepared. The monomers and polymers were characterized by IR and NMR techniques. Thermal stability of the polymers were determined by TG analysis. The composition of the copolymer was determined using ¹H-NMR analysis. The reactivity ratios of the monomers were determined by the application of Finemann–Ross and Kelen–Tudos methods. The prepared copolymers were tested on leather for their pressure sensitive adhesive property.     

Influence of the comonomers (styrene and methyl acrylate) on the rate of photocrosslinking of 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}‐ phenyl acrylate

[2,6‐Bis(4‐hydroxybenzylidene)cyclohexanone] (HBC) was prepared by reacting cyclohexanone and p‐hydroxybenzaldehyde in the presence of acid catalyst. Acrylated derivative of HBC, 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}phenyl acrylate (HBA), was prepared by reacting HBC with acryloyl chloride in the presence of triethylamine. Copolymers of HBA with styrene (S) and methyl acrylate (MA) of different feed compositions were carried out by solution polymerization technique by using benzoyl peroxide (BPO) under nitrogen atmosphere. All monomers and polymers were characterized by using IR and NMR techniques. Reactivity ratios of the monomers present in the polymer chain were evolved by using Finnman–Ross (FR), Kelen–Tudos (KT), and extended Kelen–Tudos (ex‐KT) methods. Average values of reactivity were achieved by the following three methods: r₁ (S) = 2.36 ± 0.45 and r₂ (HBA) = 0.8 ± 0.31 for poly(S‐co‐HBA); r₁ = 1.62 ± 0.06 (MA); and r₂ = 0.12 ± 0.07 (HBA) for poly(MA‐co‐HBA). The photocrosslinking property of the polymers was done by using UV absorption spectroscopic technique. The rate of photocrosslinking was enhanced compared to that of the homopolymers, when the HBA was copolymerized with S and MA. Thermal stability and molecular weights (M_w and M_n) were determined for the polymer samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2494–2503, 2004     

Study of mechanical properties of urethane-chlorinated rubber graft copolymer system. I

The isocyanate-terminated urethane prepolymer was prepared from toluene diisocyanate and a mixture of castor oil-polypropylene glycol (PPG) (MW 2000). The chlorinated rubber (CR) graft copolymers (A and B) containing small percentage of hydroxyl groups were mixed with the urethane prepolymer in different proportions (1:1, 2:3, and 1:2), and the films were cast using these systems. Tensile strength and percent elongation were evaluated for A and B series with and without triethanolamine (TEA). Morphological characteristics of the films were also studied by using a scanning electron microscope (SEM). Deviations noticed in tensile strength values at yield as well as at break for A and B series and for the samples cured with additional TEA have been discussed.     

Kinetic studies on the condensation reaction of 2-methylol-4-t-butylphenol with 4-t-butylphenol using acid catalysts. I

The rates of the individual reactions of 2-methylol-4-t-butylphenol with 4-t-butylphenol were measured under varying mole ratios of reactants in the presence of different acid catalysts (5.0 × 10^?3 N to 2.0 × 10^?4 N) at five different temperatures (60, 65, 70, 75, and 80°C). In all the experiments, the reactions were found to obey second-order rate law. The values of the Arrhenius parameters and the entropy of activation for the overall reaction were calculated. The relative catalytic efficiencies of the acid catalysts followed the order HNO₃ > HCl > H₂SO₄.     

Selective oxidation of secondary amines over titanium silicalite molecular sieves,TS-1 and TS-2

Titanium silicalite molecular sieves, TS-1 and TS-2 having MFI and MEL structures, respectively, catalyze the oxidation of secondary amines to the corresponding hydroxylamines using hydrogen peroxide as the oxidant. Higher concentrations of H₂O₂ lead to further oxidation of hydroxylamine to nitrone. Diffuse reflectance spectroscopy shows the formation of a titanium peroxo complex upon addition of hydrogen peroxide to the TS-1 catalyst. The titanium peroxo complex oxidizes the substrate and reforms to a titanyl group.     

COMBINED FORCED AND FREE CONVECTION IN BOUNDARY LAYER FLOW OF NON-NEWTONIAN FLUID ON A HORIZONTAL PLATE

An analysis is presented to study the effects of buoyancy-induced streamwise pressure gradients on laminar forced convection heat transfer to non-Newtonian fluids from a horizontal plate. Numerical solution of the transformed boundary layer equations has been carried out for different values of the flow behavior index and the buoyancy parameter by means of the local nonsimilarity method. A discussion is provided for the effect of the buoyancy force on the friction factor, the dimensionless heat transfer rate and the details of the velocity as well as temperature fields.     

Cocoa butter extenders from Kokum (Garcinia indica) and Phulwara (Madhuca butyracea) butter

Cocoa butter extenders, suitable for use in chocolate and confectionery, were prepared from Kokum fat and a Phulwara butter fraction. The latter fraction was prepared from Phulwara butter by two-stage dry fractionation and blended with Kokum fat in selected proportions to obtain a series of hard butters with different melting profiles. The blends with higher proportions of Kokum fat were harder and hence may find application in warm climates. The blends with higher proportions of Kokum fat were harder and hence may find application in warm climates. The blends had solidification properties, fatty acid and triacylglycerol compositions similar to those of cocoa butter. In addition, they had narrow melting ranges like cocoa butter, and they were compatible with cocoa butter and have tolerance toward milk fat.     

Photodegradation of phenoxyacetic acid and carbamate pesticides on TiO2

An equation representing photocatalytic degradation rate of three phenoxyacetic acid and two carbamate pesticides was proposed, which includes substrate adsorbability to TiO₂ and Hammett’s constant of substituent groups. The data fitting to this equation indicated that the adsorption was a predominant factor in determining the degradation rate. A study was also conducted on the degradation process of 4-chloro-2-methylphenoxyacetic acid (MCP) by identifying aromatic (4-chloro-o-cresol, 4-chlorocatechol and methylhydroquinone) and aliphatic acid (acetic, formic, glyoxylic and glycolic acids) intermediates. Particularly acetic acid formation was related to methyl substituent on aromatic ring.     

A comparative study of tetraisobutyldialuminoxane and methylaluminoxane as cocatalysts for Cp2ZrCl2 catalyzed ethylene polymerization

Summary The effect of [A1]/[Zr] mol ratio and temperature on the cocatalytic effects of tetraisobutyldialuminoxane (TIBDAO) and methylaluminoxane (MAO) for ethylene polymerization using Cp₂ZrCl₂ catalyst were studied. The decay type kinetic profile was observed for both TIBDAO and MAO cocatalyzed ethylene polymerizations. Catalytic activity and rate of polymerization were found to be low for TIBDAO cocatalyzed ethylene polymerization when compared to MAO cocatalyzed ethylene polymerization. The differences in catalytic activity and rate of polymerization for ethylene polymerization catalyzed by Cp₂ZrCl₂-TIBDAO and Cp₂ZrCl₂-MAO were discussed with respect to the structures of MAO and TIBDAO. An active species for Cp₂ZrCl₂-MAO and Cp₂ZrCl₂-TIBDAO catalyzed ethylene polymerizations was also discussed. The polyethylene was characterized by intrinsic viscosity measurements.     

Cyclopropanation of Olefins Using a Silica Gel Anchored Palladium Phosphine Complex

A silica gel anchored palladium phosphine complex is synthesized and used as a catalyst for the first time in the cyclopropanation of several olefins using ethyl diazoacetate as a carbene source.