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The kinetics of polymerization of acrylamide (AM) initiated by manganese(III) acetate–ethoxyacetic acid (EAA) redox system in aqueous sulphuric acid was investigated in the temperature range 35–45°C. The effects of variations in [monomer], [Mn3+], [EAA], [H+], and ionic strength on the rates of monomer disappearance (Rp) and Mn3+ disappearance (−Rm) were studied. The polymerization process is initiated by the free radical arising from the oxidation of ethoxyacetic acid by Mn3+ and terminated by the mutual combination of growing polymer radicals. Based on the kinetic results, a suitable reaction scheme is proposed and the rate expressions are derived. The study on degree of polymerization supports the proposed scheme for polymerization. The various rate and thermodynamic parameters are evaluated.

Melt-polycondensation of poly(ethylene terephthalate) (PET) and 3-bromo-p-acetoxybenzoic acid or 3,5-dibromo-p-acetoxybenzoic acid in different mole ratios yielded random copolyesters. The copolyesters have higher Tgs than PET because of an increase in mol % of the substituted p-oxy-benzoate units and follow Wood's equation for copolymer Tgs. Using this equation, we calculated the Tgs of the homopolymers of 3-bromo-p-oxybenzoate and 3,5-dibromo-p-oxybenzoate, which are not available experimentally, to be 113 and 123°C, respectively. Up to certain percentages of the comonomer composition the copolyesters exhibited cold crystallization and melt transitions which we attribute to the crystallizable segments of PET. The variation in melting temperatures in the composition of the copolymer was explained by Flory's theory. The differences in the melting behavior of the polymer, annealed at various crystallization temperatures for a constant time interval, throws light on the morphological changes that took place in it. Using the Hoffman and Weeks method, we determined the extrapolated equilibrium melting temperatures of these copolyester which were used to calculate the enthalpy of melting for the crystallizable units.

The kinetics and mechanism of polymerization of acrylamide (AM) initiated by manganese (III) acetate (MTA)-diglycolic acid (DGA) redox system in aqueous sulfuric acid were studied in the temperature range 20-35°C. The overall rates of polymerization and the disappearance of Mn 3+ and the kinetic chain lengths of polyacrylamide were determined. The polymerization reaction is initiated by the organic free radical arising from the Mn 3+ -diglycolic acid reaction and the termination is by the metal ions. The rate of polymerization of acrylamide was found to be proportional to the first power of monomer and diglycolic acid and independent of manganese(III) acetate. The various rate parameters were evaluated.

By exposure to ultraviolet and gamma radiation and by the usual methods of thermal polymerization, the stereospecific polymerization of methyl aryloxymethacrylates was carried out at different temperatures in several solvents. Triad tacticity values of the polymers obtained by free-radical and ionic routes were computed from nuclear magnetic resonance spectral data. Results of this investigation support our earlier observation that, under the conditions used, heterotactic content is the maximum in most of these polymers, thereby justifying the high steric effect of the bulky and polar aryloxy side chain which offers equal isotactic and syndiotactic placements.

New 1:1 alternating copolymers of 2-methyl-2-oxazoline with (i) α-chloroacrylic acid and (ii) α-bromoacrylic acid were synthesized and characterized by i.r., n.m.r. and the products of alkaline hydrolysis. The copolymerization occurred at a temperature of 60°C without any added catalyst or initiator. The copolymerization kinetics were studied and the order with respect to each monomer was found to be unity. A scheme for the copolymerization involving a zwitterion intermediate is proposed.

Polymer blends of thermosetting and thermoplastic polymers were developed by properly mixing them in the presence of compatibilizers. Two compatibilizers that are structurally and chemically similar to thermosetting and thermoplastic polymers and a compatibilizer that does not have such similarity were synthesized. Polymer blends of phenol formaldehydepoly(methyl methacrylate) and phenol formaldehyde-polystyrene were prepared by using the compatibilizers, poly(phenol formal dehyde-s-triazine-methyl methacrylate), P(PF-g-MMA), poly(phenol formaldehyde-s-triazine-styrene), P(PF-g-S), and poly (cinnamaldehyde-co-oxy propylene oxy isophthaloyl-cooxy propylene oxy fumaroyl), P(C-g-E). The effects of molecular weight and quantity of the copolymer on the compatibility of the polymer were examined. The optimum compatibility which leads to superior tensile properties of the present blends was observed with P(PF-g-MMA) and P(PF-g-S) copolymers. The superior properties were also found to occur only in the range of the optimum molecular weight and quantity of the copolymer present in the blend. The polymer blends were analyzed by differential scanning calorimetry (DSC) and Electron Microscopy. DSC scans of P(PF-g-MMA) and P(PF-g-S) copolymer blends showed a single Tg whereas the scans of P(Cg-E) copolymer blends showed an additional Tg for unblended thermoplastic fractions. The electron microscopy studies also revealed good compatibility in P(PF-g-MMA) and P(PF-g-S) copolymer blends in which the unblended thermoplastic fractions are negligibly less. The UV-vacuum and heat resistance of the P(PF-g-MMA) and P(PF-g-S) copolymer blends were found to be good.

Terephthalate unsaturated copolyesters with ethylene glycol and 2-butene-1,4-diol, with ethylene glycol and 2-butyne-1,4-diol, with ethylene glycol and diethylene glycol, and with 2-butyne-1,4-diol were synthesized by trans-esterification reactions. Proton nuclear magnetic resonance spectroscopy was used to elucidate the structures of the copolyesters. The intrinsic viscosities of the copolyesters were measured in o-chlorophenol at 30°C. The number-average molecular weights of these copolyesters were determined by using a vapor pressure osmometer. The thermal behaviors of the copolyesters were studied by differential thermal analysis and are discussed in terms of structural differences.

Random copolyesters of dimethyl terephthalate (DMT), ethylene glycol (EG) and propane-1,3-diol (PrG) and the homo-polyesters poly(ethylene terephthalate) (PET) and poly(trimethylene terephthalate) (PPrT) have been subjected to differential thermal analysis (DTA) and thermogravimetry (TG). Thermodynamic parameters like enthalpy of fusion (ΔHf), entropy of fusion (ΔSf) and percent crystallinity (Xc) are discussed in terms of structural differences, particularly the effect of composition and chain flexibility. Kinetic order and activation energy for the thermal degradation of the copolyesters are discussed.

High polydispersity values obtained for the molecular weights, as determined by light scattering, osmometry, and GPC, of polymers prepared by different methods from the monomers recently synthesised indicate the presence of large quantities of low molecular weight species besides the high molecular weight species besides the high molecular weight species. Intrinsic viscosity data were used to evaluate Mark–Houwink constants K and “a” for this new series of monomers. DSC analyses show that the polymers have low Tg. X-ray diffraction studies made on the fibers show a high percentage of crystallinity in poly(methyl α-phenoxymethacrylate).

Random copolyesters of dimethyl terephthalate (DMT), ethylene glycol (EG), and butane-1,4-diol (BD) and the homopolyesters poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) have been subjected to degradation and pyrolysis studies. Differential thermal analysis (DTA) showed that the decomposition temperature is dependent on the percentage of EG and BD present in the copolyesters. Thermal volatilization analysis (TVA) also showed that the decomposition temperature is dependent on the percentage of EG and BD present in the copolyesters. The trend for the decomposition temperatures obtained from TVA studies for these copolyesters is similar to such other thermal properties as melting temperature Tm, ΔHf, ΔHc, etc. The subambient thermal volatilization analysis (SATVA) curves obtained for these polymers are also presented. The SATVA curve is the fingerprint of the total volatile products formed during the degradation in high vacuum. The isothermal pyrolysis of these materials was carried out in high vacuum at 450°C. The products formed were separated in a gas chromatograph and were subsequently identified in a mass spectrometer. The major pyrolysis products from PBT were butadiene and tetrahydrofuran, whereas those from PET were ethylene and acetaldehyde. The ratio of acetaldehyde to ethylene increases with the EG content in the copolyester, suggesting a different decomposition mechanism compared to the decomposition mechanism of PBT and PET.

The glass transition temperature of the random copolyesters of poly(ethylene terephthalate) and p-hydroxybenzoic acid prepared by molten state polycondensation increases with increasing concentration of p-oxybenzoate units (oxy-1,4-phenylenecarbonyl units). The observed values of the glass transition temperature are compared with the values predicted from various empirical equations on the Tg's of copolymers and the concave Tg composition curve is explained in terms of the internal stiffening effect of the p-oxybenzoate unit. The melting temperatures of the copolyesters vary with composition and show an eutectic phase diagram. The melting temperature and enthalpy of fusion of the homopolymer of p-hydroxybenzoic acid were determined making use of Flory's equation on the melting point of a copolymer.

Random copolyesters were prepared from dimethyl terephthalate (DMT), ethylene glycol (EG) and butane 1,4-diol (BD) by melt-polycondensation techniques, using varying amounts of EG and BD. Compositions have been established by 1H n.m.r. spectroscopy. Intrinsic viscosity and number average molecular weight ( M n ) were measured. Thermal properties have been studied by differential thermal analysis. Melting and crystallization temperatures and thermodynamic parameters are discussed in terms of structural differences, particularly the effect of composition and chain flexibility. The degree of crystallinity from differential thermal analysis, i.r. and wide angle X-ray scattering (WAXS) are discussed.

Modified copolymers or compatibilizers were prepared to blend thermosetting (phenol formaldehyde resin) and thermoplastic (PMMA/PS) polymers. Two compatibilizers, modified phenol formaldehyde-(s-triazine)-polystyrene, P(PF-g-S) and poly-(cinnamaldehyde-co-oxypropyleneoxyisophthaloyl-co-oxypropyleneoxyfumaroyl), P(C-g-E), were synthesized and characterized. The behaviour of the compatibilizers towards UV vacuum irradiation and heat was studied with low molecular weight P(PF-g-S) and P(C-g-E). Crosslinking was found to occur during the initial 20 h of UV vacuum irradiation, which was confirmed by solubility and swelling data. Thermal degradation of thermoplastic segments in P(PF-g-S) was found to occur initially during thermal exposure. Crosslinking of the degraded radical fragments and phenolic segments took place in the continued thermal exposure. A method yielding a simultaneous interpenetrating network (SIN) was adopted to increase the molecular weight of P(PF-g-S) and its allied copolymers which is a prerequisite for the present polymer blends. Condensation reaction in phenolic segments and addition reaction in thermoplastic segments were carried out simultaneously, the former reaction was carried out thermally and the latter by photo irradiation. Es wurden modifizierte Copolymere oder Kompatibilisierungsmittel hergestellt, um Duromere (Phenol-Formaldehyd-Harze) und Thermoplaste (Polymethylmethacrylat/Polystyrol) zu mischen. Zwei Kompatibilisierungsmittel, modifiziertes Phenol-Formaldehyd-(s-triazin)-Polystyrol(P(PF-g-S)) und Poly(Zimtaldehyd-co-oxipropylen-oxi-isophthaloyl-co-oxipropylen-oxifumaroyl (P-(C-g-E))) wurden hergestellt und charakterisiert. Das Verhalten der Kompatibilisierungsmittel gegen UV unter Vakuum und Hitze wurde an P(PF-g-S) und P(C-g-E) mit niedrigem Molekulargewichtuntersucht. Vernetzung trat wuhrend der ersten 20 h der UV Bestrahlung unter Vakuum auf, sie wurde uber Loslichkeits- und Quellungsdaten festgestellt. In der An-fangsphase der thermischen Belastung wurden die thermoplastischen Segmente im P(PF-g S) abgebaut, bei weiterer Warmeeinwirkung vernetzten die radikalischen Bruchstucke und die phenolischen Segmente. Uber Durchdringungsnetzwerke (interpenetrating networks) wurde das Molekulargewicht der P(PF-g-S) und der verwandten Copolymeren erhoht, was fur die vorliegenden Polymere erforderlich ist. Kondensationsreaktionen in phenolischen Segmenten und Additionsreaktionen in thermoplastischen Segmenten wurden gleichzeitig durchgefuhrt, erstere thermisch und letztere durch Photobestrahlung.

The particle size distribution of suspension copolymers of styrene, chloromethylstyrene, and divinylbenzene prepared with gelatin and poly(diallyldimethylammonium chloride) as suspension stabilizers can be varied widely by variation of the relative amounts of monomer and aqueous phases, the stirring speed, and the amount of added anionic surfactant sodium dodecylbenzenesulfonate.

Oberonia wynadensis is described from India. It belongs to the subgenus Oberonia and is related to O. acaulis and O. verticillata in having the flowers arranged in whorls.

A fewα, α-disubstituted vinyl monomers were prepared for the first time : They have been polymerized and characterization of these polymers is in progress.

The kinetics of polymerization of acrylamide (AAM) and methacrylamide (MAM) with manganese(III) acetate as thermal initiator was studied. In the temperature range between 303 and 313 K, the initial rate of polymerization follows the relation: v=k[Monomers] · [Initiator] ½ . The rate of initiation of the polymerization was determined from the rate of decomposition of manganese(III) acetate. The reactivity of the two monomers under the same conditions was compared.

Department of Physical Chemistry, University of Madras, A. C. College Campus, Madras-600 025 Kinetics of Polymerization of Acrylamide Initiated by Lead Tetraacetate in Aqueous Acetic Acid

Random terephthalate copolyesters of ethylene glycol and butane-1,4-diol of various compositions were prepared by trans-esterification of poly(ethylene terephthalate) (PET) with butane-1,4-diol (BD). Proton nuclear magnetic resonance spectroscopy (NMR) was used to elucidate the structure and compositions of copolyesters. The thermal behaviour of the copolyesters were investigated by differential thermal analysis (DTA). Intrinsic viscosities were measured in orthochlorophenol at 30°C.

The monomer reactivity ratios of methyl phenoxymethacrylate (MPMA), methyl p-cresoxymethacrylate (MCMA) and methyl p-nitrophenoxymethacrylate (MNMA) were evaluated both by Fineman-Ross and Kelen-Tudos methods. The tendency to form alternating copolymers of these monomers is discussed.

Department of Physical Chemistry, University of Madras, A C. College Campus, Madras-600 025 Heat and impact resistant plastic foam of dehydrochlorinated poly(vinyl chloride) (DHPVC)-poly(oxy propylene oxy isophthaloyl-co-oxy propylene oxy fumaroyl) (PPPF) was prepared for cryogenic insulation in liquid propellant tanks of space vehicle. The foam was prepared by the method of hot compacting and chemical blowing. High temperature resistant, high tensile strength and optimum impact resistant foams were obtained by the formation of crosslinked DHPVC-CO-PPPF copolymer and the blend DHPVC/PPPF/DHPVC-CO-PPPF during the process of foaming. The copolymer and the blend were separated individually from the plastic foam. The effect of foaming period on the crosslinking of DHPVC and PPPF was studied by determining the swelling value and \(\bar{M}\)n of the copolymer. The compatibility of DHPNC and PPF was investigated by uv, ir and DSC studies. The effect of \(\bar{M}\)n of the copolymer on the compatibility was studied by DSC.

Department of Physical Chemistry, University of Madras, A. C. College Campus, Madras-600 025 (India) Manuscript received 80 July 1976, accepted 22 July 1978 The kinetics of oxidative hydrolysis of acetaldoxime(AAO), propionaldoxime(PAO), butyraldoxime(BAO) and benzaldoxime(BNAO) leading to carbonyl compounds have been examined. The second-order rate constants (k,), the Arrhenius energy of activa­tion(Ea), the frequency factor(A), the entropy of activation(∆S#) and the free-energy of activation(∆G#) were evaluated and discussed. A mechanism in accordance with the kinetic data is proposed.

Epoxy resin is chosen for our present study owing to its exceptional combination of properties such as easy processing, high safety, excellent solvent and chemical resistance, toughness, low shrinkage on cure, good electrical, mechanical and corrosion resistance with excellent adhesion to many substrates. This versatility in formulation made epoxy resins widely applied for surface coatings, adhesives, laminates, composites, potting, painting materials, encapsulant for semiconductor and insulating material for electric devices. There are numerous paint/coating systems based on epoxy resin available for corrosion and fouling prevention. They however are not completely satisfactory in field applications, where high corrosion, fouling and flame resistance are required. The demand for epoxy resin as corrosion/fouling resistant coatings is restricted mainly due to its inferior characteristics like poor impact strength, high rigidity, and moisture absorbing nature besides inadequate flame retardant properties. It is for this reason that silicones and phosphorus-based compounds are used as modifier in this work by intercrosslinking network mechanism (ICN) to obtain epoxy resin with desired properties ideally suitable for field applications for preventing corrosion and fouling with flame retardantancy. The present work involves the development of solvent free silicone/phosphorus modified epoxy coating systems, since solvent free coating systems are widely used for numerous applications due to their lower cost per unit film thickness, freedom from fire and pollution hazard and ability to provide better performance. For the development of coating systems, epoxy resin (X) serves as base material, hydroxyl terminated dimethylsiloxane (HTPDMS) as modifier, aminopropyltriethoxysilane (APS) as crosslinking agent and dibutyltindilaurate (DBTDL) as catalyst. Polyamidoamine (A), aromatic amine adducts (B) and phosphorus-containing diamine (C) were used as curing agents. The study also describes the evaluation of corrosion resistant behaviour of unmodified epoxy and siliconized epoxy coatings by potentiodynamic polarization method, electrochemical impedance spectroscopy (EIS), salt-spray and antifouling tests. The results are discussed., CSIR. National Metallurgical Laboratory. Madras Centre. Fundação para a Ciência e Tecnologia.