Polyesters. I. Rate of polyesterification of γ-arylitaconic acids with ethylene glycol

A kinetic study of the polyesterification reaction of γ-phenyl- γ-p-methoxyphenyl-, and γ-p-chlorophenylitaconic acids (1 mole) with ethylene glycol in the presence or in absence of p-toluenesulfonic acid as a catalyst has been carried out in order to show the effect of substituents on the rate and degree of polymerization. The reaction of 1 mole of the acid and an excess of ethylene glycol has also been studied. In all cases the reaction is found to follow the second-order rate equation. The mechanism of polyesterification has been discussed. In catalyzed polyesterification electron-withdrawing groups (CI) decrease the velocity of the reaction. The low values of ρ in both the auto-catalyzed and catalyzed reaction indicate that this polyesterification is slightly sensitive to the polar nature of the substituent.     

Polyesters. part IV. Structural elucidation of γ-phenylitaconic polyesters by joint application of I.R., U.V. and NMR spectroscopy

Infrared, u.v. and NMR spectroscopy have been used for both qualitative and quantitative analyses of polyester resins and their hydrolyzate products, after curing with styrene. Application of the analytical procedure to each of the polyester resins is described in detail. The average number of styrene molecules for each fumarate group present in the hydrolyzate products of polyesters (II), (III) and (IV) has been determined, as well as the number of reacted fumarate groups per copolymer chain.     

Graft polymerization of monomers onto cellulose and lignocelluloses by chemically induced initiator

The presence of a low percentage of lignin retards and inhibits the graft polymerization reaction of some vinyl monomers on lignocellulosic substrates. The retardation or inhibition effects of lignin in situ are discussed.     

Synthesis and study of polymerization and copolymerization of some oligounsaturated esters—V

A number of oligoacetylenic acrylates have been synthesized and characterized. The i.r. as well as the physical and chemical properties show the probable formation of oligomers possessing a proposed structure. The oligomers undergo further reaction in the presence of peroxide initiators to give crosslinked products. The i.r. spectra of the crosslinked products show that the oligomers undergo addition polymerization on the terminal double bonds. The triple bond in these oligomers is relatively unreactive under the conditions of polymerization, while that in the glycolic residue is reactive to a certain extent, as indicated by the higher per cent conversion of the oligomers having such unsaturated glycolic residue.Copolymerization of various oligoacetylenic acrylates, methacrylates and esters with terminal allylic group with styrene give crosslinked products. The polymers and copolymers are pale yellow in colour, glassy, insoluble in organic solvents and infusible; the copolymers were more rigid than the homopolymers. The volume shrinkage of various oligomers during polymerization lies between 5 and 13 per cent.     

In vitro antimicrobial evaluation and in silico studies of coumarin derivatives tagged with pyrano-pyridine and pyrano-pyrimidine moieties as DNA gyrase inhibitors

Molecular Diversity - Several coumarin-containing substitute nitrogen heterocycles have recently received considerable importance due to their diverse pharmacological properties. One-pot and rapid...     

Tests of a fiber-optic velocity transducer

A novel transducer is developed and tested. The transducer utilizes optical fiber to measure mean and instantaneous flow rates in turbulent flows, and is capable of detecting flow reversal. Calibration of the transducer is conducted in both air and water. The dynamic response of the transducer is tested against hot-wire anemometery in the wake flow of a circular cylinder over a wide range of Reynolds number.List of symbols C _D drag coefficient - D diameter of cylinder - d diameter of fiber - E modulus of elasticity of the fiber - e output voltage - F drag force per unit length of a cylinder - f frequency (Hz) - L length of the fiber cantilever - M magnification factor - m mass per unit length of the fiber - Re Reynolds number - q dynamic pressure (= 1/2 U ²) - U free stream velocity - density - v kinematic viscosity