Mrinal M. Maiti

Biodegradability of gelatin—PF resin blends by soil burial method

Abstract Cured gelatin-phenol formaldehyde (PF) resin blends have been tested for their biodegradability under soil burial test conditions. Over a period of two weeks and at an ambient temperature of 27 °C, the blends were found to be significantly resistant to biodegradation in the test soil up to a composition of 7:3 gelatin to resin ratio. At higher gelatin contents, the blends suffered extensive degradation. Scanning electron micrographs of the blend films after the tests showed extensive bacterial growth. Inorganic inclusions, presumably calcium salts, that are inherently present in gelatin are believed to support bacterial growth and biodegradation of the blends.

Polymerization of N-vinylcarbazole over cobalt (II) exchanged 13X molecular sieves

Abstract Polymerization of N-vinylcarbazole over Co(II)-13X molecular sieves in toluene solution has been studied. The rate of polymerization has been observed to be second order both in monomer concentration and in the exchange level of Co(II), and linearly dependent on catalyst loading. An apparent activation energy of 8.71 kcal mol−1 (36.41 kJ mol−1) has been found for the polymerization. The effect of different parameters on molecular weight has also been studied. The general kinetic features of the reaction are somewhat different from those reported for monomers like isobutyl vinyl ether, styrene etc. on simple and rare earth exchanged 13X molecular sieves.

A titrimetric method for estimation of fluorine in organic compounds

A simple and rapid titrimetric method for estimation of fluorine in organic compounds and fluoropolymers is reported. It involves combustion of the sample in oxygen, absorption of the combustion products in an aqueous solution of Ce(III) nitrate and glycerol, containing hexamethylenetetramine, and finally titration with EDTA, with Xylenol Orange and Methylene Blue as screened indicator.

Durability tests on polymer-cement mortar

Abstract Accelerated durability tests on several polymer-impregnated mortars have been studied in aqueous sulphuric acid (3:1 v/v) and hydrochloric acid (3:1 v/v) media. In addition to the reactivity of individual polymers and cement body in these corrosive environments, the cement-polymer interaction has been identified as an important factor which controls the durability properties of the composites.

N-vinylcarbazole polymerization by 13X molecular sieve exchanged with Mn (II), Co(II), Ni(II), Cu(II) and Zn(II)

Abstract The polymerization of N-vinylcarbazole by 13X molecular sieves modified by five different transition metal ions, viz. Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), has been studied under various conditions. The order of reactivity follows the trend: Mn(II) ≈ Cu(II) > Co(II) > Zn(II) > Ni(II) at pH ∼ 3.55 and an exchange level of 30% of the metal ion. The polymerizations are believed to occur by a dual-ion-initiation mechanism in which both metal ions and proton centres participate. The overall energy of activation (Ea) for each system decreases with decreasing pH of the exchanging salt solution. Average activation energy on proton centre (EH) and that on metal ion centre (Ea) have been evaluated for each system. Ea, EH and Ec have been shown to correlate with one another. The molecular weights and their distributions are affected by the nature of the metal ion and also by the protonic centres. The possibility of a correlation of the catalytic activity of the modified 13X with ionic radius, electronegativity and normal co-ordination number has been examined.

Polymerisation of dithiocarbamates by oxidative coupling using iodine as oxidant—I. Synthesis and characterisation

Abstract A novel polymer has been synthesised by reacting hexamethylene diamine with carbon disulphide by the oxidative coupling method using iodine as oxidant. The first step of the polymerisation involves the formation of dithiocarbamate by reacting a diamine with carbon disulphide in alkaline medium at low temperature (5–10°) in a protic solvent such as alcohol or water. Next, the dithiocarbamate is coupled with a diamine using iodine as the oxidant at ambient temperature. The polymerisation proceeds by a radical mechanism. The molecular weight of the polymer is not very high (∼ 12,000); it is soluble in polar solvents. It was characterised by elemental analysis (N, S) and i.r. and NMR spectroscopy. The physical characteristics have been studied.

New Accelerators for Vulcanization of Rubber—Part III: Synthesis, Characterization, and Evaluation of Some 2-Mercaptobenzimidazole Derivatives

Abstract Five derivatives of 2-mercaptobenzimidazole containing S—N bonds have been synthesized and evaluated for their action as accelerator-antioxidant in NR gum stocks. All these compounds exhibit varying degree of accelerating efficiency; some of them, viz. MBSTP, MBSPT, and MBDSPT, offer excellent cure characteristics and vulcanizate properties comparable to some of the best commercially available curatives such as CPTD. Substitution at the N or S atom of the MB molecule does not affect adversely its antioxidant properties; rather, an improvement in aging resistance has been achieved. The degree and nature of substitution play an important role in the antioxidation properties of these MB derivatives. Thus, disubstitution offers better antioxidation characteristics than monosubstitution, and the latter, in turn, is better than unsubstituted MB. Some discussion on correlation of reactivities of these MB derivatives and their cure synergism with CPTD have been reported. It was observed that these new ac...

Solubility characteristics of poly(N-vinylcarbazole) prepared by Co(II) loaded 13X molecular sieve

During the polymerization of N-vinylcarbazole (NVC) by Co(II)-13X the resultant polymer (¯Mn=6000) is soluble in benzene or toluene but partly soluble in methylethyl ketone (MEK). To ascertain whether the MEK insolubility is due to polymer tacticity, the polymer has been further characterized by13C NMR analysis. The atactic structure of polyN-vinylcarbazole (PNVC) initiated by Co(II) has been established from a comparison of methine carbon () peaks with the same for a cationic PNVC(BF3/Et2O, isotactic) and radical PNVC (AIBN, atactic).

Structure Property Relationship in Unsaturated Polyamides

Abstract Unsaturated polyamides from fumaric acid and ortho-, meta- and para-phenylene diamine were prepared by thionyl chloride activated low temperature polycondensation in polar solvents. The polymers were found to be soluble in highly polar solvents. The solubility parameter of the polymers was calculated from Smalls group contribution, which agreed well with the experimental values. X-ray diffraction study revealed that the polymers were amorphous. The isomeric effect on the thermal and electrical properties of polymers was discussed.

Effect of Solvents on the Network Order in Poly(Polyethylene Glycol) Phosphates

Abstract A set of network polymers (PPEGPs) obtained by polycondensation of polyoxyethylene glycols and phosphorous oxychloride, have been characterized in respect of their paracrystalline behavior both in dry and solvent-swollen states. A definite structure property correlation has been established between the polyoxythylene (POE) link length at one hand, and their XRD patterns and degree of swelling at the other.