NOPR Collection:

A theoretical investigation of the lowest Bu state of trans-butadiene

2019-03-19T04:32:51Z

Title: A theoretical investigation of the lowest Bu state of trans-butadiene Authors: Rai, Sachchida N; Buenker, Robert J Abstract: Results of an ab initio CI study of the lowest singlet B_u state of trans-butadiene are presented. It is found that a minimum exists for the 1 ¹Bu state of the present system in a geometry in which all C - C bond lengths are equal and both terminal CH₂ groups are rotated by 10°. An attempt is made to provide an interpretation of the appearance of the broad intense π-π* band in the spectrum of trans-butadiene. Page(s): 215-218

Thermal properties of ABA and BAB triblock copolymers

2019-03-19T04:30:40Z

Title: Thermal properties of ABA and BAB triblock copolymers Authors: Maiti, Sukumar; Shit, Subhas Chandra Abstract: Thermal studies (TGA and DSC) of various ABA and BAB copolymers have been made and the crosslinking and swelling behavior of the polymers have been reported in order to establish the suitability of these polymers for their application as thermoplastic elastomers. From the thermal recycling and outdoor stability studies it is concluded that the ABA copolymers having polyester as the hard block and butadiene based rubber as the soft block would be suitable for use as thermoplastic elastomers. Addition of appropriate antioxidants increases the outdoor stability and thermal recycle ability of these block co-polymers. Page(s): 219-226

Solvation behaviour of cupric chloride in non-aqueous solvents

2019-03-19T04:29:34Z

Title: Solvation behaviour of cupric chloride in non-aqueous solvents Authors: Singh, Prem P; Soni, Manjula; Maken, S Abstract: Electromotive force measurements have been made at 303.15K on the cell Cu_xHg/CuCl₂-(m) (in solvent S; S=FD, W or DMF)/AgCI/Ag where FD=formamide, W=water and DMF=dimethylformamide. The data obtained suggest that while FD and W favour deposition of Cu²⁺ from the solution onto the copper amalgam electrode in the order FD > W, DMF favours dissolution of metallic copper in the concentration range 0 < m < 0.0056 (the effect becomes more pronounced as m -> 0), but it favours deposition of Cu²⁺ ions from the solution onto the copper amalgam when m > 0.0056. This has been explained on the basis of kinetics of electrode processes. Equilibrium constants for the dissociation processes as also the respective degrees of dissociation have been obtained by iterative procedure. The standard electrode data of the above cell have also been evaluated in FD, Wand DMF and the same have been utilized to evaluate standard molar Gibbs free energy of transfer of CuCl₂ from W -> FD or DMF. The data have been considered in terms of solute-solvent interactions. Page(s): 227-231

Studies on solute-solvent interactions in aqueous solution of isomeric mono-hydroxybenzoate salts

2019-03-19T04:27:21Z

Title: Studies on solute-solvent interactions in aqueous solution of isomeric mono-hydroxybenzoate salts Authors: Chatterjee, D K; Seal, B K Abstract: Measurements of the relative viscosities of aqueous solutions of sodium salts of o-, m- and p-hydroxybenzoic acids in the temperature range 298-308 K have revealed that among the three salts, o- hydroxybenzoate has the smallest B-coefficient and it behaves as a structure breaker while the meta- and para-isomers act as water structure makers, the structure forming capacity of the latter two being almost the same. The energy of activation data support the above conclusions. The smaller B-coefficient of o- hydroxybenzoate ion may be due to involvement of the ortho-hydroxyl group in intra- and inter-molecular hydrogen bonding with the carboxylate group and the solvent water respectively. Since the probability of intra-molecular hydrogen bonding is absent in the case of meta- and para hydroxybenzoates, these have B-values higher than that of the o-isomer, A comparison of B-coefficients of the three isomeric mo no- hydroxybenzoate salts with that of sodium benzoate at 298 and 308 K shows that introduction of an hydroxyl group destroys partly the hydrophobic character of the benzene ring in the benzoic acid molecule. Page(s): 232-236