677.044.22 T. I. Samsonova, and O. A. Roshchina Studies were conducted to evaluate the indexes of the accuracy of methods of determining the mass fraction of oil on chemical fibres and data were obtained on the accuracy of the methods. The values of the standard deviations of the repeatability and the standard deviation of the reproducibility for each method are presented in the form of the wt. percent content in absolute form. Based on the results of the studies conducted in the SRISF Testing Center together with Studies to establish indexes of the accuracy of methods of determining the mass fraction of oil on chemical fibres for a new intergovernmental standard to replace GOST 29332-92 are reported [1]. Two methods of removing the oil from the fibre are proposed in the new standard: a shaker is used in the first and a Soxhlet apparatus is used in the second. The accuracy of the methods is established in the entire range of measurements of the oil content. The studies were conducted in accordance with the requirements of GOST R ISO 5725-2002 [2].An interlaboratory experiment involving laboratories that constantly measure the mass fraction of oil on a fibre was conducted to establish the accuracy of the methods. The testing laboratories at SRISF, Grodnokhimvolokno, Khimvolokno Amtel Kuzbass, Saratovorgsintez, Mogilevkhimvolokno, and Svetlogorsk Khimvolokno IA participated in the experiment using the shaker, and the laboratories at SRISF and Mogilevkhimvolokno participated in the experiment using the Soxhlet apparatus.Samples of the fibres with different levels of oil content (test level), one close to the lower boundary of the range of measurements, the other close to the upper boundary, while the remainder were positioned between them, were prepared for conducting the interlaboratory experiment. The experiment using the shaker was conducted on eight test levels, and the experiment with the Soxhlet apparatus was conducted on five levels ( Table 1).The analytical samples were prepared in accordance with . The coded samples were sent to the laboratories involved in the experiment. The tests in each laboratory were performed by the same person, on the same equipment in accordance with the methods in draft GOST 29332. The oil was extracted from the fibre samples with n-hexane* (samples No.
UDC 677.051.125.262:677.494.745.32 and Yu. V. ValetkinWe present comparative results of tests on commercial and experimental platinum/palladium spinnerets in forming polyacrylonitrile fi lament yarn of 50 tex. The experimental spinnerets were made with holes of high precision diameter (0.08±0.001 mm). The spinnerets were characterized by their integrated throughput (the fl ow-through time for distilled water) while the fi lament yarns were characterized by their linear density. We demonstrate a correlation between the fi lament linear density and the fl ow-through time. In this case, the criteria for uniformity of the fi lament with respect to linear density (variance, range, mean-square deviation, coeffi cient of variation) are statistically signifi cantly smaller for the experimental spinnerets than for the commercial spinnerets.We know that chemical fi lament yarns and tows have transverse nonuniformity (with respect to cross section) and longitudinal nonuniformity (with respect to length) [Ref. 1, p. 213]. Transverse nonuniformity is determined by the irregularity of individual fi laments in a strand [2], while longitudinal nonuniformity is determined by the nonuniformity in the properties of fi lament yarns in an arbitrary length segment [3]. The reason for both types of nonuniformity is assumed to be the nonuniformity of the individual fi laments in the cross section of the fi ber strand. It is due to nonuniformity in the properties of the polymer system to be processed (solution, melt) [1], the precision within which the spinneret holes are made [2, 4-6], the conditions for forming and subsequent treatments in the production steps for obtaining the chemical fi bers [1][2][3][4][5][6].In the literature, generally parameters are given describing the nonuniformity in the physical and mechanical properties of fi laments, where the determining parameter is considered to be the nonuniformity in the transverse cross section [3,4]. Furthermore, insuffi cient information is available about the reasons for the nonuniformity and the parameters describing it for fi lament yarns as a whole. And high irregularity, for example with respect to linear density, reduces the unit breaking load (strength) of the fi laments. Therefore study of the irregularity in fi lament yarns continues to be an important problem, especially study of the correlation between the linear density of fi lament yarns and the precision of the geometric characteristics of the spinneret.There have been many attempts to theoretically and experimentally study the correlation between tolerances for the diameter and length of the spinneret hole and the nonuniformity of the individual fi bers with respect to thickness. A comprehensive review of this work is given in [7]. It is reported in particular that:-the coeffi cient of variation for the diameters of individual fi laments of a polyvinyl alcohol fi ber is approximately equal to twice the coeffi cient of variation for the diameters of the spinneret holes [2]; -the distribution curves for the calculated ...
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