Sorption characteristics of needle-punch and modified materials

Abstract

The use of bicomponent fibre in needle-punch materials and processing them on a calender results in materials that combine high sorption characteristics and mechanical strength. The optimum content of bicomponent fibre for obtaining fibre sorbents with high sorption capacity is 7-12% and the calendering speed is greater than 4 m/min. The size of the capillaries in the needle-punch materials formed during needle punching ensures that they are partially filled with liquids.The effective use of fibre sorbents requires developing parameters for evaluating their sorption capacity and its dependence on the structure of the materials. The index G m (kg/kg), equal to the ratio of the mass of the sorbed liquid to the mass of the sorbent, is usually used as such a parameter [1][2][3][4][5]. The analysis of the use of this parameter for assessing the sorption capacity of fibre materials demonstrated its dependence on the chemical nature of the liquids [1,4,5]. Its dependence on the structural characteristics of the materials is complex in shape [1,5], which makes it difficult to model the structure of the materials with a given sorption capacity. We investigated sorption of liquids by needle-punch and modified materials and developed a criterion for assessing their sorption characteristics.Samples of needle-punch materials with a different surface density made from polyester fibre with a linear density of 0.33 tex by the mechanical method of forming fibre webs were investigated. The bulk density of the samples was varied by altering the punching density from 120 to 700 cm 2 . Samples based on a blend of polyester and bicomponent fibres (poly(ethylene terephthalate) core), polypropylene shell) [6] were also used to increase the mechanical strength of the fibre sorbents processed on the calender [7]. The concentration of bicomponent fibre in the materials varied from 7 to 30%, the calender shaft temperature varied from 150 to 220°C, and the calendering speed varied from 1.2 to 15 m/min. The sorption characteristics of the needle-punch and modified materials were determined with the method in [1,5].In processing the experimental data, a linear dependence ( Fig. 1) was established between parameter (G V , m 3 /m 3 ), calculated as the ratio of the volume of the sorbed liquid (V l , m 3 ) to the sample volume (V sam , m 3 ), and the real volume of the porosity of the samples per unit of area (V r , m 3 /m 2 ). Use of parameter V r for assessing the porosity of the needlepunch materials is substantiated in [1,4,8]. The linear dependences of the sorption capacity in this system of coordinates are also characteristic of modified materials with a different bicomponent fibre content (C, wt. %). Sorption of liquids by the needle-punch and modified materials can be evaluated with the value of the tangent of the slope of these dependences (k V , m -1 ). The proposed approach to assessing the sorption capacity of the materials excludes its dependence on the chemical nature of the liquids and is reflected by one variable in comparison to ...