SynopsisThe occurrence of nonsteady-state conditions in the melt extrusion of fibers is described. Data obtained from cinephotographs are presented which indicate that the spin line diameter a t a fixed point in space can have wide fluctuations dependent upon spinning parameters. I t is postulated that the interaction of an elastic bulge and variable spin line tension due to a melt inhomogeneity may be responsible for the effect. Some evidence for melt inhomogeneity is presented to demonstrate the existence of domains having flow properties different from the main mass of polymer melt.

No abstract

and azoisobutyronitrile (3.24 g.) were refluxed in 30 ml. of benzene for 8 hr. under nitrogen. The benzene and tetramethylsuccinonitrile were removed by steam distillation. The yellow residue was dissolved in benzene, dried, and the solvent was removed by heating on the steam-bath for 1 hr. in vacuo.The yellow glass which resulted (1.82 g.) did not form a crystalline picrate. Seeding of 187 mg. of this material in benzene-absolute ethanol with a crystal of dihydro-bis-(cyanopropyl)-benzpyrene (X, m.p. 222-224°) yielded 10 mg. of white crystals, m.p. 220-224°. Dehydrogenation of the yellow glass with sulfur at 215°a nd with 10% palladium-charcoal at 315°yielded benzpyrene as the sole identifiable product. Dehydrogenation with chloranil in boiling xylene for 47 hr. yielded an impure sample of X.Dehydrogenation of Dihydro-bis-(cyanopropyl)-benzpyrene (X).-The bis-compound X (29 mg., m.p. 208-220°) was mixed with 4 mg. of 10% palladium-charcoal and heated under nitrogen at 315°for 1 hr. in a sublimation apparatus. The sublimate was rinsed into the apparatus with benzene, the benzene was removed on the steam-bath, and the material was heated at 315°for 1 hr. more.The mixture was dissolved in benzene, filtered and was concentrated on the steam-bath under nitrogen. The residue could not be recrystallized from benzene-hexane; it was therefore sublimed at 140-165°( 0.1 mm.), and the yellow sublimate (9.2 mg.) was recrvstallized from benzene-hexane. The yellow crystals obtained (4.5 mg.) melted at 176-178°and gave no depression on mixed m.p. with authentic benzpyrene.