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A modified method with respect to an earlier conventional procedure was successfully attempted and we now report the new procedure for the synthesis of surface-grafting technique by the delayed addition of inexpensive vinyltoluene (VT) functionality to the partially polymerized supporting monomers viz., styrene (St) and divinylbenzene (DVB) via suspension polymerization. The resulting copolymer beads containing surface-enriched with methyl group were converted into a catalyst by chlorination followed by a quaternization process. Two groups (I and II) of SE-PSPTC beads were prepared by fixing the crosslinking amount (DVB) as 2% and 6%, respectively, 25% of VT as a common active site functionality and the rest of the contribution was styrene. Each group contains six different catalysts based on the concentration of active sites on the surface which in turn depends upon the partial polymerization time (PPT) of St/DVB i.e., 0, 3, 6, 9, 12, and 15 hrs. These two different groups and 6 different catalysts categ...

We prepared two batches of surface-enriched (with active sites) polymer-supported phase-transfer catalysts (SE-PSPTC) by fixing the crosslinking monomer divinylbenzene (DVB) at 2% (first batch) and 6% (second batch) through a free-radical suspension copolymerization method with vinylbenzyl chloride (VBC; 25%) as a functionality and with styrene (St) as a supporting monomer, followed by the quaternization of the resulting terpolymer beads with triethylamine. The enrichment of the active sites on the surfaces of the beads was accomplished by a surface-grafting technique through the delayed addition of the functional monomer (VBC) to the partially polymerized copolymer beads of poly(St/DVB). To bring the active sites fully onto the surfaces, we prepared six different types of terpolymer beads in each batch by varying the partial polymerization time (PPT) of St/DVB-0 h [0 VBC (conventional)], 3 h (3 VBC), 6 h (6 VBC), 9 h (9 VBC), 12 h (12 VBC), and 15 h (15 VBC)-and then gradually adding the functional monomer (VBC) to the partially polymerized poly(St/DVB) system. The resulting terpolymer beads, containing different concentrations of pendant benzyl chloride (-CH 2 Cl) on the surface in each batch, underwent facile quaternization [-CH 2 N + (C 2 H 5 ) 3 Cl - ] with an increase in the PPT of St/DVB and remained constant at 12 VBC and 15 VBC. To asses the superiority of the catalysts according to the surface enrichment of the active sites, particularly between conventional (0 VBC) catalysts and other PPT-based SE-PSPTCs, we characterized all the catalysts by estimating the chloride-ion concentration, by using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), EDAX, and ESCA, and by carrying out the dichlorocarbene addition to olefins. The chloride-ion concentration by the Volhard method and the peak intensity of the C-N stretching absorbance concentration, that is, the quaternary onium group in the FTIR spectra of both batches, increased with the PPT of St/DVB in both batches of catalysts. In particular, the chloride concentration of a first-batch catalyst of a representative mesh size (-120 + 140) had a twofold enhancement between the conventional catalyst (0 VBC; 1.88 m equiv g -1 ) and 9 VBC/SE-PSPTC (3.74 m equiv g -1 ), although the same amount of the functional monomer was added in both preparations. These results showed the higher enrichment of the active site on the surface of 9 VBC, and the same trend was also maintained for second-batch catalysts, regardless of the catalyst mesh size. SEM images of both batches showed that there was a higher concentration of nodules [due to the grafting of poly(VBC)] on the surfaces of the beads of 9 VBC/SE-PSPTC and the aforementioned PPT catalysts than on the surfaces of the conventional catalysts (0 VBCs), which exhibited smooth surfaces (because of the simultaneous addition of all three monomers). This observation confirmed the enrichment of active sites on the surfaces. In the EDAX analysis, up to a depth of 0.5-1 μm, the surface chloride concentration increased from 0 VBC to 9 VBC/SE-PSPTC and remained constant in 12 VBC and 15 VBC, first-batch catalysts of a representative mesh size (-120 + 140). The same trend was also observed in second-batch catalysts, indicating the enrichment of the onium group more on the surface in 9 VBC/SE-PSPTCs.

l-Proline lithium bromide monohydrate (LPLBM), a promising semiorganic nonlinear optical material, was synthesized and single crystals of LPLBM were grown from solution by slow evaporation technique. Single crystal X-ray structure solution reveals that the grown crystal belongs to monoclinic system with space group P21. Presence of various functional groups was identified by FT-IR and FT-Raman spectral analyses. UV-Vis-NIR spectroscopic study shows that the LPLBM crystal possesses 90% of transmittance in the range of 250-1100nm. Vickers microhardness values, the dielectric constant and dielectric loss of the LPLBM crystal were reported. Elemental analysis by energy dispersive X-ray analysis shows the presence of carbon, nitrogen, oxygen and bromine. The surface morphology of the crystal was investigated using scanning electron microscopic study. The thermal stability of the LPLBM crystal was studied from TGA and DSC analysis. Second harmonic generation efficiency of the LPLBM crystal measured by Kurtz and Perry powder technique using Nd:YAG laser is about 0.3 times that of urea.

The anionic manganese (III) porphyrin was immobilized onto crosslinked poly(benzylpicoline-co-styrene) resin through coordinate linkage. The immobilized metalloporphyrin was employed as a heterogeneous catalyst for the hydroxylation of cyclo-octane by NaOCl. The observed reaction rates depend on experimental parameters such as stirring speed, substrate amount, temperature, and catalyst amount. The influence of different polymer-based axial ligands, particle size, and percent crosslinking of the polymer support was also discussed. The imidazole-based polymer supports show higher rate constant values than the pyridine-based supports. The catalyst shows significant decrease in catalytic activity on recycling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 104–111, 2000

The kinetics of phase transfer catalyzed free radical polymerization of alkyl methacrylates (MMA and EMA) using potassium peroxomonosulphate (water-soluble initiator) coupled with phase transfer catalyst viz., tetrabutylphosphonium chloride (TBPC) have been investigated in ethylacetate-water biphase system at 50 ± 0.1°C. The rate of polymerization increased with an increase in the quaternary salt concentration, but showed a tendency to level off at a higher concentration. An increase in peroxomonosulphate concentration also increased the rate of polymerization (Rp). The order with respect to monomer was found to be in unity. A square root order was observed for both peroxomonosulphate and phase transfer catalyst. A suitable kinetic scheme has been proposed to account for the experimental data and its significance is discussed.

This article presents the systematic study of kinetics and mechanism of phase-transfer-catalyzed free-radical polymerization of acrylonitrile (AN) and watersoluble initiator potassium peroxomonosulphate (PMS) coupled with tetrabutyl phosphonium chloride (TBPC) in ethyl acetate/water biphase system in the temperature range 45-55°C at fixed pH and ionic strength. The rate of polymerization increases with an increase in concentrations of AN, PMS, and phase transfer catalyst, PTC. It was observed that R p is proportional to [AN] 1.5 , [KHSO5 5 - ] 0.5 , and [TBPC] 0.5 . A suitable kinetic scheme has been proposed to account for the experimental observations and its significance was discussed.

Polymer-supported phase transfer catalysts with active sites mostly on the surface were prepared by suspension copolymerization of styrene (St), divinylbenzene (DVB), and vinylbenzyl chloride (VBC) with AIBN, followed by the quaternization of the resulting copolymer beads with triethylamine. Active sites on the surface were achieved by the delayed addition of functional monomer (VBC) to the partially copolymerized St/DVB. Polymer beads enriched with active sites were characterized by SEM, EDAX, FTIR, and ESCA. The electron micrographs showed that the exterior surface of delayed-addition functional monomer catalysts (type 1) has a large number of nodules attached to the surface compared to the smooth surface exhibited by the conventional type 2 catalyst upon the simultaneous addition of all three monomers. In the EDAX analysis up to a depth of 100 A, the surface chloride of type 1 peak intensity is greater (compared with type 2), indicating the CH2Cl enrichment on the surface. In FTIR, the peak intensities of the CN stretching (quaternary onium group) in type 1 are greater than those of type 2, confirming the evidence of more quaternization on the surface than in the bulk. From ESCA analysis to a depth of about 30 A, it was found that type 1 (beads) contains 26% and type 2 contains 14% of covalent chloride on the surface, which strongly supports the grafting of VBC on St/DVB. In the estimation found by the Volhard method, type 1 has 4.73 m eq g−1 and type 2 has 2.29 m eq g−1 of ionic chloride, thus supporting the surface grafting of VBC. The catalytic activity of these two different catalysts was tested by studying the reaction, that is, the C-alkylation of phenylacetone. The rate constants of this reaction for type 1 are almost twofold greater than those of type 2, a finding that could uphold the preceding experimental observations. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 408–418, 2000

Insoluble poly(4-vinylpyridine-co-styrene) beads are prepared using divinylbenzene as the crosslinking agent. These polymer beads are converted into poly(4-vinylpyridine-N-oxide) (PVPNO) under peracetic acid conditions. The resulting polymer is functionalized with titanium tetrachloride (TiCl4) to afford the corresponding PVPNO-TiCl4 complex. This complex shows good catalytic activity for esterification reactions. The kinetics of formation of n-octylacetate from acetic acid and n-octanol is reported. The effects of stirring speed, reactant concentration, catalyst amount, percent crosslinking, particle size, and temperature on the conversion is investigated. The rate constants are found to increase with an increase in the stirring speed, concentration of n-octanol, catalyst amount, and temperature and decrease with an increasing percentage of crosslinking and the mesh size of the polymer beads. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2075–2080, 2000

Crosslinked poly(4-vinylpyridine-co-styrene) was prepared and functionalized with titanium tetrachloride to afford the corresponding poly(4-vinylpyridine-co-styrene)-titanium tetrachloride complex. This insoluble functionalized polymer-supported catalyst shows good catalytic activity for esterification reactions. In this article, the kinetics of esterification of acrylic acid with n-butanol is reported. The rate of formation of product depends on many experimental parameters, viz., stirring speed, concentration of acrylic acid, catalyst amount, temperature, percent active site, percent crosslinking, and mesh size of the polymer catalyst. The reaction rates were found to increase with increase in the stirring speed, concentration of acrylic acid, catalyst amount, and temperature, and decreases with increasing percentage crosslinking and mesh size of the polymer beads. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 727–733, 1997

In the title coordination polymer, {[Li(C2H5NO2)2(H2O)]Br}n, the Li+ cation is coordinated by three carboxylate O atoms of zwitterionic glycine molecules and by a water molecule, forming a distorted tetrahedral geometry. One of the two glycine molecules bridges neighbouring complexes, forming an infinite chain parallel to the c axis. Polymeric chains are further linked by extensive hydrogen bonds involving the Br− anions and glycine and water molecules, producing a three-dimensional network.

In the title compound, C2H5NO2·C8H6O4, the glycine molecule exists as a zwitterion (2-azaniumylethanoate) with a positively charged amino group and a negatively charged carboxylate group. In the crystal, N—H...O and O—H...O hydrogen bonds link the components into layers parallel to the ab plane. The central part of each layer is composed of hydrogen-bonded glycine zwitterions, while phthalic acid molecules interact with the zwitterions in such a way that benzene rings protrude up and down from the layer.

A Labrador retriever pup with a bilateral dermoid in the eyes was treated successfully by the use of a unipolar hand held electrocautery unit., Štene pasmine labrador retriver s obostranim dermoidom u očima bilo je uspješno izliječeno upotrebom jednostranog ručnog elektrokautera.

Insoluble microporous polystyrene-bound diphenylamine-titanium tetrachloride complex has been used as a catalyst in the ketalization of cyclohexanone with ethylene glycol. The kinetics of the reaction was studied, and a suitable mechanism was proposed based on the results obtained. The observed reaction rates depend on many experimental parameters, viz., stirring speed, concentration of cyclohexanone and ethylne glycol, temperature, percent active site (percentage of ring substitution), and percent crosslinking of the polymer. The rates were found to increase on increasing the stirring speed from 0 to 500 rpm and then decrease from 500 to 800 rpm. The rate of ketalization increases with increasing concentration of ethylene glycol, catlyst amount, and temperature, and decreases with increasing concentration of cyclohexanone and percentage crosslinking of the polymer.

A three step synthesis of novel ‘multi-site’ water soluble phase transfer catalyst viz., α,α′-bis(triethyl ammonium methylene chloride) β-phenyl ethene and its utility in various organic biphase reactions are described.

The kinetics of phase-transfer catalyzed free-radical polymerization of acrylonitrile (AN) was carried out with water-soluble initiator peroxomonosulphate (PMS) with phase-transfer catalysts (tetrabutylammonium chloride and benzyltributylammonium chloride (TBAC and BTBAC) in tolune/water two-phase systems in the temperature range of 45–55°C at fixed pH (4) and ionic strength. The rates of polymerization (Rp) were evaluated at various values of [PMS], [PTC], and [AN]. It has been observed that the rates of polymerization increase with an increase of [AN], [PMS], and [PTC]. A kinetic scheme has been proposed to account for the experimental observations. © 1994 John Wiley & Sons, Inc.

The kinetics of phase-transfer-agent-assisted free-radical polymerization of methyl methacrylate using K2S2O8 as the water-soluble initiator and triethylbenzylammonium chloride (TEBA) as the phase-transfer catalyst (PTC) was investigated in toluene-water biphase media at 60°C. The effect of varying [MMA], [K2S2O8], [TEBA], [H+], the ionic strength of the medium, and the temperature on the rate of polymerization (R p) was studied. R p was found to be proportional to [MMA]2, [K2S2O8]1, and [TEBA]0.5. Based on the kinetic results, a mechanism involving initiation of polymerization by phase-transferred S2O8 2- and termination by Q+ (quaternary ammonium ion) is proposed.

Following the chemical reaction method pure and doped lead hydrogen phosphate single crystals were grown in silica gel using different gel density, various concentrations of phosphoric acid, and lead nitrate solutions. As the gel pH plays an important role in the formation of different H 3 PO 4 species in the phosphoric acid system, the pH range in which HPO 4 -2 ions dominate, was considered which in turn is necessary for the growth of lead hydrogen phosphate crystals. Characteristics of these crystals were carried out by infrared spectral analysis and microhardness study

Insoluble microporous polystyrene-bound benzyltriethyl ammonium chloride has been used as a catalyst in the alkylation of phenylacetone with 1-bromobutane, and the kinetics of this reaction was investigated under phase-transfer catalytic conditions. The observed reaction rates depend on many experimental parameters, viz., stirring speed, substrate amount, basicity of aqueous NaOH, amount of 1-bromobutane, temperature, order of addition of the reactants and particle size, percent active site, and percent crosslinking of the polymer. The rates are nearly 12 times higher at lower concentrations of base than at higher concentrations and do not vary appreciably with a variation in stirring speed from 200 to 700 rpm. The rate of alkylation increases with a decrease in the particle size of the catalyst and crosslinking of the polymer. Based on the results obtained, a suitable mechanism in which a combination of intraparticle diffusion and intrinsic reactivity limit the reaction rates has been proposed. © 1993 John Wiley & Sons, Inc.

Supernumerary nipples are common congenital anomalies, most often occurring along the embryonic milk lines. We present a patient with an ectopic nipple on the foot. We are unable to explain the aetiology of this anomaly; however, several theories have been proposed. They are also associated with disorders of the renal and cardiovascular systems as well as pathology that affect normal breast tissue.

Amino acid family crystals exhibit excellent nonlinear optical and electro optical properties. l -Ornithine monohydrochloride single crystal, belongs to the amino acid group, was grown by the slow evaporation solution growth technique at room temperature. The grown crystals were characterized by single crystal and powder X-ray diffraction analysis, Fourier transform infrared (FTIR) spectroscopy, TGA, DTA and DSC analyses. UV–vis–NIR spectrum shows excellent transmission in the UV, visible and NIR region (300–1600 nm). The mechanical properties of grown crystals were studied using Vickers microhardness tester. Its second harmonic generation efficiency was tested using Nd:YAG laser and is 1.25 times that of KDP.

The alkylation and cycloalkylation of phenylacetonitrile (PAN) with excess of 1-bromobutane and 1,4-dibromobutane respectively catalyzed by aqueous NaOH and insoluble polystyrene-bound benzyltriethylammonium chloride were studied and the rates depend upon several experimental parameters. The rate of cycloalkylation of PAN is five times faster than the alkylation and the former proceeds even in the absence of the solid catalyst. Both alkylation and cycloalkylation gave higher rates in reverse addition method than in direct addition. Deprotonation of PAN by hydroxide ion takes place without participation of the polymeric catalyst. The electrostatic force between the positive charge on the nitrogen atom of catalyst and carbanion is responsible for alkylation of active nitrile with polystyrene-bound phase-transfer catalyst. The rates of both the reactions increase with increased stirring speed, ring substitution, hydroxide ion concentration and catalyst amount and decrease with increased particle size and the degree of cross-linking of the polymer. Apparent activation energies for the reactions were calculated. The kinetic results are discussed in terms of mass transfer and a combination of intraparticle diffusion and intrinsic reactivity limitations of the rates.

Nonlinear optical single crystals of ammonium pentaborate (APB) were grown by the slow cooling method from aqueous solution. Grown crystal was characterized by powder X-ray diffraction (PXRD) and FT-IR spectral analysis. Perfection of the grown crystal was evaluated by high-resolution X-ray diffractometry (HRXRD). The effect of nylon threading on the perfection of the grown bigger crystal was also studied by HRXRD. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. Thermal properties were investigated by TG-DTA and DSC analyses. Its mechanical hardness was estimated by Vickers microhardness tester.

Single crystals of gamma-glycine were grown from a mixture of glycine, water and lithium bromide. Single crystal X-ray diffraction analysis confirmed the growth of gamma-glycine phase. Presence of various functional groups of gamma-glycine was identified by FTIR spectrum. Optical absorbance spectrum recorded in the wavelength range of UV-vis-NIR revealed that this crystal has good optical transparency in the range 250-1500 nm. Vickers microhardness values were estimated on the prominent (100) face. Thermogravimetric and differential scanning calorimetric analyses were carried out to study the thermal properties of gamma-glycine. Second harmonic generation efficiency of the crystal measured by Kurtz's powder method using Nd:YAG laser is about three times that of KDP.

This paper presents the design and analysis of a compact microstirp fed wide band printed dipole antenna operating in L band. The dipole antenna bandwidth is improved by flaring of dipole arms, tapering ground plane, and the best impedance matching is achieved by introducing an open circuited stub with dipole arm. Parametric study is carried out to study the effect of dipole length and arm width on the antenna resonant frequency and bandwidth has also been investigated. The antenna is printed on FR4 substrate and the simulated return loss bandwidth is validated by the measured result. The fabricated antenna provides a wide bandwidth of 51.2% at the centre frequency of 1.3 GHz and the peak gain of 3.2 dB which is suitable for phased array radar applications.

A new proximity-coupled patch antenna is designed using a novel concept for wide impedance bandwidth of 2.3 GHz that corresponds to an impedance bandwidth of 30% (S11

Secondary surveillance radar (SSR) aids in the identification of aircrafts and often works in conjunction with the primary radar for better target awareness. An important module of the SSR system is the reply signal processor unit. One of the major issues in reply processing is the occurrence of garbled replies, which occurs due to the overlapping of replies. Overlapping occurs when range difference between the two targets is less than de-garble resolution (3045 m). In practical scenarios SSR replies are often garbled (e.g.: formation flights). So efficient de-garbling algorithms are required for providing the target identification. In this paper a new algorithm towards de-garbling of SSR replies is discussed. The information derived from the delta to sigma ratio channel (Delta/Sigma) and the Sigma (sum) channel of the monopulse receiver are effectively combined for separating the garbled replies

An attempt is made to achieve a wide band antenna element with low return loss for a surveillance radar application. A stepped probe fed capacitively coupled patch is chosen and the step size & step length are optimized to give 20% bandwidth for 20dB return loss or 40% bandwidth for 10dB return loss.

Potential for EMI measurement application of a quadrifilar helical antenna is investigated through computer simulated design and testing for a given set of specifications.

In the title coordination polymer, {[Li(C2H5NO2)2(H2O)]Br} n , the Li(+) cation is coordinated by three carboxyl-ate O atoms of zwitterionic glycine mol-ecules and by a water mol-ecule, forming a distorted tetra-hedral geometry. One of the two glycine mol-ecules bridges neighbouring complexes, forming an infinite chain parallel to the c axis. Polymeric chains are further linked by extensive hydrogen bonds involving the Br(-) anions and glycine and water mol-ecules, producing a three-dimensional network.

In the title compound, C2H5NO2·C8H6O4, the glycine mol-ecule exists as a zwitterion (2-aza-niumyl-ethano-ate) with a positively charged amino group and a negatively charged carboxyl-ate group. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the components into layers parallel to the ab plane. The central part of each layer is composed of hydrogen-bonded glycine zwitterions, while phthalic acid mol-ecules inter-act with the zwitterions in such a way that benzene rings protrude up and down from the layer.

The vestibulo-ocular reflex stabilizes vision in many vertebrates. It integrates inertial and visual information to drive the eyes in the opposite direction to head movement and thereby stabilizes the image on the retina. Its adaptive nature guarantees stable vision even when the biological system undergoes dynamic changes (due to disease, growth or fatigue etc), a characteristic especially desirable in autonomous robotic systems. Based on novel, biologically plausible neurological models, we have developed a robotic testbed to qualitatively evaluate the performance of these algorithms. We show how the adaptive controller can adapt to a time varying plant and elaborate how this biologically inspired control architecture can be employed in general engineering applications where sensory feedback is very noisy and/or delayed.

A systematic study of the thermal polymerization of α-chloroacrylic acid and α-bromoacrylic acid in aqueous nitric acid was carried out. The effect of variation of monomer concentration lead tetraacetate concentration, hydrogen ion concentration, ionic strength, and temperature on the rate of monomer disappearance was carried out. Based on the experimental observations, suitable reaction schemes were proposed for the polymerization of the above monomers. The rate constants and the thermodynamic parameters were evaluated.

The kinetics of redox -initiated polymerization of acrylic acid (AA) by the systerm Mn 3+ -isobutyric acid (IBA) in sulfuric acid was studied in the temperature range of 35-50°C. The overall rates of polymerization (R p ), disappearance of manganic ion (−R m ), and degree of polymerization (X n ), were measured with variation in [monomer], [Mn 3+ ], [IBA], H + , μ, [Mn 2+ ], and temperature. The polymerization is initiated by the organic free radical that develops from the Mn 3+ -isobutyric acid oxidation reaction. Two types of termination reactions, one by the metal ion (Mn 3+ ) and the other by the MN 3+ -isobutyric acid complex are proposed to explain the kinetic results. The various rate parameters were evaluated an discussed.

The oxidative cleavage of some aliphatic ketoximes by thallium(III) acetate was studied in the temperature range of 20-40°C. The reactions were followed by determination of the rates of disappearance of thallium(III) acetate for variations in [substrate], [Tl(III)], [H + ], ionic strength, temperature, etc. The reactions were found to be totally second order-first order with respect to each reactant. The second-order rate constants and thermodynamic parameters were evaluated and discussed. The mechanism proposed involves one-electron oxidation to the iminoxy radical followed by an another one-electron oxidation to the hydroxynitroso compound which dimerizes and decomposes to give the carbonyl compounds and hyponitrous acid.

Differential thermal analysis of random terephthalate copolyesters of ethylene glycol and butane-1,4-diol showed that the thermal properties (Tm, Tc, ΔHf, ΔSf, and Xc) follow an independent curve with comonomer composition. The kinetics of thermal degradation of these copolyesters were studied by thermogravimetry and the major degradation mechanism was found to be unimolecular.

The kinetics of γ-radiation-induced bulk polymerization of methyl phenoxymethacrylate and methyl paracresoxymethacrylate was studied at dose rates of 0.3 and 0.075 Mrad/h and at temperatures of 0 and 30°C. The polymerization was first order with respect to the monomers and the rate of polymerization had a direct dependence on dose rate. The activation energy value for the polymerization of methyl phenoxymethacrylate was 1.2 and 0.7 kcal/mol for methyl paracresoxymethacrylate. The polymerization proceeded predominantly by an ionic mechanism.

Random copolyesters of different compositions were synthesized by melt polycondensation of poly(ethylene terephthalate) and 3-bromo - and 3,5-dibromo-p-hydroxybenzoic acids. The copolymer compositions were determined by proton nuclear magnetic resonance spectroscopy. The thermal behavior of these copolyesters was investigated by differential scanning calorimetry. The glass transition temperature, crystallization temperature, and decomposition temperature were found to increase with increase in the paraoxybenzoate content of the copolyesters. The limiting viscosity number and the weight-average molecular weight were determined.

The kinetics of the thermal polymerization of methyl acrylate (MA) and acrylamide (AAM) initiated by manganic ion in aqueous sulfuric acid medium has been studied. The rate of disappearance of [monomer] (Rp) was found to bear a square dependence on monomer and to be independent of [Mn2+] in the case of both the systems. Rp for acrylamide increased with the increase in [H+] but that for methyl acrylate remained almost constant. The degree of polymerization of the polymers (Xn) determined viscometrically was directly proportional to the [monomer] and inversely proportional to [Mn3+], for both systems. Xn increased with an increase in [H+] in the case of acrylamide and decreased in the case of methyl acrylate. Suitable reaction schemes to explain these experimentally observed facts have been proposed. Kinetic and thermodynamic parameters are also evaluated.

The kinetics of polymerization of acrylamide (AM), acrylic acid (AA), and acrylonitrile (AN) initiated by the redox system Mn 3+ -diglycolic acid (DGA) was studied. All three systems followed the same mechanism; namely, initiation by an organic free radical arising from the oxidation of diglycolic acid and termination by the interaction of polymer radicals with Mn 3+ ion. The rate coefficients k i /k 0 and k p /k t were related to monomer and polymer radical reactivity, respectively. An inverse relation between monomer and polymer radical reactivity was observed. Monomers with higher Q values gave higher k i /k 0 values but lower k p /k t values. The e values of the monomers were important in determining the reactivities of monomers with nearly the same Q values.

The kinetics of polymerization of acrylic acid (AA) and methacrylamide (MAM) initiated by the redox system Mn3+ -ethoxyacetic acid (EAA) in aqueous sulphuric acid was studied at 35°C. The polymerization of both the monomers followed the same mechanism, viz., initiation by the primary radical arising from the oxidation of EAA and termination by the Mn3+ ion. The rate coefficientski/k0 andkp/ki were correlated to monomer and polymer radical reactivities, respectively. Acrylic acid was found to have higher monomer and polymer radical reactivities than methacrylamide.

Terephthalate copolyesters of ethylene glycol and propane-1,3-diol of various compositions were prepared by trans-esterification of poly(ethylene terephthalate) (PET) with propane-1,3-diol [PrG(1,3)] . The compositions of the coDolyesters were determined by1H NMR. The melting and crystallization temperatures were measured by differential thermal analysis (DTA). Intrinsic viscosities were measured in orthochlorophenol at 30°C.

This article describes a new, spontaneous, 1:1 alternating copolymerization between a Schiff base, N-benzylidine aniline (NBA), and α-haloacrylic acids (XAA) such as α-chloroacrylic acid (ClAA) and α-bromoacrylic acid (BrAA). The structure of the copolymers was identified by nuclear magnetic resonance (NMR) and infrared (IR) spectra. By using the isolation method we determined the order of each monomer. On the basis of kinetic studies, a mechanism that involves initiation, propagation, and termination by zwitterion is proposed. The effects of copolymerization under various conditions were studied and the intrinsic viscosity and number-average molecular weight were measured. The overall energy of activation, ERp, for the copolymerization was determined and thermal degradation studies were made.