Fibre extrusion

Similar considerations regarding both dispersion and quick colour changes in wire extrusion also apply to fibre extrusion. When combined with gear pumps, the dynamic 

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The polymer V containing 67 moles % of p-oxybenzoyl units was marketed by the Carborundum Co. as Ekkcel 12000. According to Jackson 35), the properties of this copolymer, which melts at 380 °C, are highly anisotropic when it is injection-moulded at 400 °C but the melting point proves too high for fibre extrusion. 

Riekel, C., and Vollrath, F. "Spider silk fibre extrusion Combined wide- and small-angle X-ray microdiffraction experiments". Int. J. Biol. Macromol. 29(3), 203-210 (2001). 

The use of conical twin screw extruders for the extrusion of wood filled PVC has also been presented (156). The characterisation of apparent viscosity for PVC wood fibre extrusion has been carried out and quadratic models used to establish tolerances within which the dimensional and physical specifications were achieved (69). 

Fibre-reinforced NR composites are manufactured by various processes, the most common being extrusion, injection moulding and compression moulding (Figure 9.6). To fabricate glass-reinforced NR composites with unidirectional long fibres, extrusion is not used because this process can only result in short fibre-reinforced polypropylene composites (a few millimetres at most). 

With the advance of LCP technology, considerable attention has been directed towards the blending of LCPs with conventional polymers (6-9). Indeed, the presence of a LCP as a minor component in a conventional synthetic fibre offers several major benefits. For example, the low melt or solution viscosity of the LCP facilitates fibre extrusion (7), and the fibre mechanical performance, notably tenacity and initial modulus, can be improved by virtue of the superior mechanical properties of the LCP (8,9). However, incompatibility between the conventional polymer and the LCP will result in poor interfacial adhesion between the two phases, with the result that the reinforcement offered by the LCP may be severely diminished. 

Black Fibre - for staple and continuous tape and fibre extrusion, characterized by a very high level of dispersion, with a carbon black content of 30-40%. 

Figure 12.5 Arrangement for liquid colour pre-blended with polymer granules for fibre extrusion. Reproduced with permission from Colour Matrix. 2008, Colour Matrix)...

Recent progress in the technology of fibre extrusion has important implications for the optimum scale of production and, ultimately, for the structure and organization of the fibres supply industry. 

A characteristic of LCP molecular orientation is their anisotropy -a natural consequence of having such a rigid molecular structure. This polymer structure is exploited for the development of high material extension and chain orientation in a fibre-extrusion process. A conventional polymer (e.g. PET) is assumed to be in a random coil con-... 

K. Hanawalt, Natural fibre extrusion. Plastics, Additives and Compounding 4 (11), 22-5 (2002). 

Lacty produces PLA pellets for film and fibre extrusion. 

Deformation of a solution usually either by spreading or by extrusion as used in making cast film and certain synthetic fibres and filaments. 

The most important of the esters is cellulose acetate. This material has been extensively used in the manufacture of films, moulding and extrusion compounds, fibres and lacquers. As with all the other cellulose polymers it has, however, become of small importance to the plastics industry compared with the polyolefins, PVC and polystyrene. In spite of their higher cost cellulose acetate-butyrate and cellulose propionate appear to have retained their smaller market because of their excellent appearance and toughness. 

Our aim was to use extrusion-cooking and to investigate its effect on some pectin-rich materials, especially citrus fibres. 

The effects of extrusion-cooking mainly on citrus fibres will be now detailed on samples which have been, unless otherwise stated, extruded in the same average conditions (SME 250kWh/t). 

An important feature concerned the degree of methylation (dm). A value of 81 % was obtained after acid extraction and a very high value of 91 % was obtained for the pectins from extruded fibres. This is an unusual value for a dm and this result shows that extrusion-cooking had a very limited effect on the methylation of the pectin. 

In addition to the conventional dyeing of acrylic fibres, there is considerable interest in so-called gel dyeing of acrylic filaments during the manufacturing process after extrusion. From the viewpoint of auxiliary usage this is outside the scope of the present work, but a useful account of the factors involved is available [61]. 

Using co-extrusion it is possible to make fibres with a nylon 6,6 inner core (Tm 264°C) and a nylon 6 outer shell (Tm 215°C). By applying pressure and heat between these two temperatures to bundles of these two fibres, a non-woven mat can be made. 

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