Rajani K. Samal

GRAFT COPOLYMERIZATION OF CELLULOSE, CELLULOSE DERIVATIVES, AND LIGNOCELLULOSE

Abstract The growth of polymer science has led to the development of new materials in direct competition with natural materials, many of which have been in use since earliest times. This has caused researchers to look more critically at both natural and synthetic macromolecules in order to learn more about their underlying structures and their relation to the properties exhibited by the macromolecules. In this regard, chemical modifications have been devised to impart certain desirable properties of both natural and synthetic macromolecules, and their applications have become an integral part of such chemical modifications. Various chemical modifications (e.g., change of functionality, oxidative degradation, inter- and intramolecular gelation, graft copolymerization), have been practiced to add improved properties to the base polymers. However, among all these methods, modification of polymers via graft copolymerization has been the subject of much interest and has made paramount contribution toward impro...

Effect of chemical modifications on FTIR spectra. II. Physicochemical behavior of pineapple leaf fiber (PALF)

This article highlights chemical modifications like alkali treatment, dinitrophenylation, benzoylation, and benzoylation-acetylation carried out on an pineapple agrowaste leaf fiber (PALF). The parent and chemically modified PALF were characterized by FTIR spectra, pH measurement, and detection of nitrogen. The percent moisture regain (extent of hydrophobicity), mechanical strength, and chemical inertness of parent and chemically modified fibers were evaluated. The modified fibers showed significant hydrophobicity, improved mechanical strength, and moderate chemical resistance.

FTIR spectra and physico-chemical behavior of vinyl ester participated transesterification and curing of jute

In this article we report the transesterification of jute with n-Butylacrylate (BA) under appropriate condition using NaOH, Pyridine (Py), and a Pyridine–acetone mixture as a catalyst. The modified vinylog jute was subsequently cured with benzoylperoxide (BPO) in acetone at 50–60°C. The parent and chemically modified jute were characterized by FTIR spectra. The percent moisture regain, mechanical strength, and behavior to common chemical reagents of the parent and modified fibers have also been tested. Transesterification and curing of jute lowered the percentage of moisture regain, imparted mechanical strength, and resistance to common chemical reagents.

Aqueous Polymerization of Methyl Methacrylate Initiated by the Mn(lll)-Fructose Redox System

Abstract The kinetics of vinyl polymerization of methyl methacrylate initiated by the redox system Mn3-fructose were investigated in aqueous sulfuric acid in the temperature range of 20-25°C, and the rates of polymerization and disappearance of Mn3+ were measured. The effect of certain water-miscible organic solvents and certain cationic and anionic surfactants on the rate of polymerization has been investigated. A mechanism involving the formation of a complex between Mn3+ and fructose whose decomposition yields the initiating free radical with the polymerization being terminated by the metal ion has been suggested.

Polymerization of Acrylonitrile Initiated by the Redox System, K2S2O8-Citric Acid Catalyzed by Silver Ion

Abstract The polymerization of acrylonitrile initiated by the redox system K2S2O8-citric acid catalyzed by Ag+ ion has been studied over the temperature range 35–50°C. The rate of polymerization is proportional to the square root of peroxydisulfate concentration. The initial rate increases with increasing citric acid concentration, but at relatively higher concentration of citric acid the rate decreases. The rate of polymerization also increases with increasing monomer concentration and temperature. The overall activation energy calculated from the Arrhenius plot was found to be 4.6 kcal/mole. On the basis of the observation, a suitable kinetic scheme has been proposed for the reaction.

Aqueous polymerization of acrylonitrile initiated by the Mn3+/citric acid redox system

Abstract Kinetics of polymerization of acrylonitrile initiated by the redox system Mn 3+ /citric acid were investigated in aqueous sulphuric acid in the range of 20–25°; initial rates of polymerization and Mn 3+ disappearance etc. were measured. The effects of certain water miscible organic solvents and certain cationic and anionic detergents on the rate of polymerization have been examined. A mechanism has been suggested involving formation of a complex between Mn 3+ and citric acid, decomposition of which yields the initiating free radical and with polymerization being terminated by mutual interaction of growing radicals.

Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Mn3+/Ascorbic Acid Redox System

Abstract Vinyl polymerization of acrylonitrile initiated by the Mn3+/ascorbic acid redox system was investigated in aqueous sulfuric acid in the temperature range of 30–45°C. The rate of polymerization Rp and the rate of Mn3+ ion disappearance were measured. The effect of additives like water -miscible organic solvents, neutral salts, complexing agents and different surfactants on the initial rate of polymerization were investigated. Depending on the results obtained, a suitable reaction mechanism is suggested which involves the formation of a complex between Mn3+ ion and the acid whose decomposition generates the initiating free radical, with the polymer chain being terminated by mutual combination of the growing chains.

Influence of Cu(II) salicylaldehyde couple on potassium monopersulphate decomposition and acrylonitrile polymerization in solution

Abstract The influences of various Cu(II) salts and Cu(II)/phenol couples on potassium monopersulphate decomposition and initiation of the polymerization of acrylonitrile have been examined in aqueous medium at 50°C. Cu(II)-sulphate/salicylaldehyde couple has been selected for detailed study of the kinetics of the polymerization. The polymerization has been studied at various concentrations of reacting components and over the range of 35 to 50°C. The rate of polymerization is given by R p = constant [Cu(II)] 0.21 [SA] 0.31 [KHSO 5 ] 0.58 [AN] 1.03 . The overall activation energy and entropy of activation of the polymerization have been calculated. From the experimental results, the catalytic efficiency of Cu(II)/salicylaldehyde couple on the KHSO 5 decomposition and acrylonitrile polymerization has been examined.

Synthesis and characterization of aniline-doped mixed copolymer resins. II

Copolymer resins were synthesized by the mixed condensation of resorcinol-CH 2 O, resorcinol-aniline-CH 2 O, resorcinol-aniline-urea-CH 2 O, resorcinol-aniline-thiourea-CH 2 O, and resorcinol-aniline-urea-thiourea-CH 2 O with a view to develop synthetic resins having improved properties and performance like toughness, mechanical properties, thermal resistance, chemical inertness, and adhesion. The resins were characterized by IR and TG analyses. The thermal analysis showed that the mixed copolymer resins have significantly better thermal stability than that of the simple phenol-CH 2 O, aniline-CH 2 O, urea-CH 2 O, and thiourea-CH 2 O resins. At 600°C, only a 50% weight loss is observed, and even at 800°C, the weight loss is about 70%. The resins are insoluble in most of the organic solvents including DMSO-d 6 . They too are unaffected by diluted HNO 3 , but dissolve in concentrated HNO 3 .

Acidic peroxo salts: A new class of initiators for vinyl polymerization—II: Kinetics of polymerization of acrylonitrile initiated by potassium monopersulphate catalysed by Mn(II)

Abstract Kinetics of the polymerization of acrylonitrile initiated by an acidic peroxo salt (potassium monopersulphate) catalysed by Mn(II) have been investigated in aqueous systems over the range 30–50°. The rates of polymerization (Rp) have been studied for various concentrations of monomer and initiator. The efficiencies of various metal salts in catalysing the polymerization have been determined from the values of Rp. The effects of catalyst (MnSO4), initiator, monomer and various aromatic and heterocyclic amines on Rp and conversion have been studied. The end-groups of the recovered polymers have been studied using standard methods. From the observed end-groups and kinetic results, a reaction scheme has been proposed, involving initiation by OH. or S O 4. radicals, generated by the interaction of the initiator with manganous sulphate, and termination by mutual combination.