Process features in production of polyolefin monofilaments

Abstract

In the assortment of polyolefin fibres and yarns, monofilaments are a low-tonnage product. For this reason, it is very difficult to separate out data on their capacities and production in pure form. In many countries, for example, in the USA and Japan, monofilaments are included in the volumes of other lines of fibres and yarns. In addition, due to the simplicity of fabrication and compactness of the units for manufacturing monofilaments, they are frequently manufactured by the users themselves, so that the statistical data on them does not always fall into the chemical fibres division.Special horizontal units have been developed for manufacturing monofilaments. They include extruder, spinning device, cooling bath, drawing stations and chambers, and winding machine. Polyolefin (polypropylene and polyethylene) monofilaments are basically used for manufacturing cables, ropes, fish and trawl nets, filter cloths and gauze, and mats and coarse canvas. The use of monofilaments in these areas in place of traditional materials is highly effective and economical due to the lower cost, lower raw material consumption, and better properties of the articles.We will discuss the effect of the production conditions on the structure and properties of polypropylene and polyethylene monofilaments below. POLYPROPYLENE MONOFILAMENTSTogether with valuable performance properties, polypropylene (PP) monofilaments have a serious drawback low abrasion resistance. Improving this index will increase the lifetime of such articles as cables, fishing tackle, filter gauze, and upholstery fabrics. In this section, we will report the result of a study of the effect of PP monofilament production parameters on their structure and abrasion resistance.Effect of the spinning conditions. Undrawn monofilaments 0.3, 0.6, and 1.2 mm in diameter (diameter of drawn monofilaments: 0.15, 0.2, and 0.5 mm) fabricated at different melt temperatures were investigated. The small melt jets coming out of the spinneret fell into a cooling bath whose temperature varied from 0 to 80°C in the different experiments.Polypropylene with an intrinsic viscosity of 2.07 (in decalin at 135°C) was the raw material. In all experiments, the distance from the spinneret to the surface of the cooling bath (10 mm), the path of the filament in the cooling bath (900 mm), and the takeup rate of the undrawn fibre (7 m/min) were kept constant. All of the samples were drawn at the rate of 49 m/min in boiling water to the same draw ratio (7 times).The structural characteristics of the monofilaments were determined with published methods [1][2][3]. All microscopic studies were conducted on a MBI-6 microscope. The x-ray patterns were taken on a URS-60 unit and the diffractograms were made on a DRON-1 x-ray diffractometer. CuK α radiation filtered with a Ni filter was used in both cases. Crystallographic plane indexes (hkl) were taken in accordance with the published criteria [4]. The abrasion resistance of the monofilaments was determined with the instrument and method described in [5] and the...