Chemical changes in polyvinyl fluoride during the process of fibre-spinning

Conclusions The change in some properties of polyvinyl fluoride during the process of fibre spinning has been investigated.It has been found that during the process of converting PVF powder into fibre, the degree of polymer crystallinity plus its resistance to thermal and thermooxidative degradation is increased; depending on the spinning regime, the densities and physicomechanical properties of PVF fibres are different.Translated from Khimicheskie Volokna, No. 4, pp. 34–35, July–August, 1984.     

N.m.r. line shape-relaxation correlation analysis of bitumen and oil sands

The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent.     

Steric requirements for coal swelling by amine bases

A set of six coals ranging in rank from lignite to hvA bituminous was swollen with a series of alkyl-substituted pyridines and a smaller set of 4-alkylanilines. The size and branching of the alkyl groups was varied and the effect of this variation on the dissolution of the amines in the coal and the resulting coal swelling was measured volumetrically. In a few cases, substituents which hindered the amine nitrogen were studied. The lignite and subbituminous coal have a much higher tolerance to branched, bulky groups than do the bituminous coals. The presence of tertiary groups in a solute strongly inhibits their dissolution in bituminous coals. Bituminous coals behave as if extensive parallel packing of structures occurs. Often, they can accept very large planar groups but have a low capacity for branched groups.     

H2S optimization for lignite liquefaction

Two lignite samples, Beulah No. 3 and Big Brown No. 1, were liquefied at 420 °C using H₂ and synthesis gas to determine the optimum beneficial amount of H₂S in the batch autoclave reactor. Under the conditions employed, 50–100 psi partial pressure of H₂S, nominally 4–10 wt% of daf lignite, was optimum for both samples. Synthesis gas outperformed H₂ with and without H₂S for the liquefaction of the two coals.     

Mechanism of void formation in cable covering

Solidification after extrusion of coaxial cables has been experimentally simulated. Solidification tests were performed with two HDPE grades and under several pressures; the extrusion velocity was varied in a suitable range so as to detect the critical velocity for void formation. A qualitative analysis of the void formation mechanism is carried out, and the predicted trends favorably compare with the critical velocity data.     

Unsaturated polyesters. II. Structure and properties of polyester resins based on cinnamylsuccinic acid

Unsaturated Polyester resins were prepared by the reaction of cinnamylsuccinic acid with saturated diols, namely, ethylene, diethylene, propylene, dipropylene, tetramethylene, and hexamethylene glycols, and the unsaturated diols, namely, 1,4-butene- and 1,4-butynediols. All the polyester resins obtained have been characterized and were found to cure with styrene, with relatively low conversions. The properties of the cured polyesters in the form of films were determined. IR and ¹H-NMR spectroscopy were used for both qualitative and quantitative analyses of the polyesters and their hydrolyzate products, after curing with styrene.