Melt Spinning of PET Fibers

An example of typical equipment used to make PET fibers is shown in this figure. Prior to melting, the polymer chips must be thoroughly dried, typically under vacuum at elevated temperatures for several hours. The equilibrium moisture content of PET under ambient conditions is about 0.4 % [3] and this much moisture would cause unacceptable levels of degradation. The dried polymer chips are fed to an extruder which melts the chips and forwards them to a 

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At the bottom of the pack the polymer exits into the air via a multiplicity of small holes through a thick plate of metal (the spinneret). The number of holes can 

A key parameter which controls the rate at which orientation is being generated is the rate of extension, as follows  

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Dutta, A., Role of Quench Air Profiles in Multifilament Melt Spinning of PET Fibers , Textile Research Journal, 57, 13-19, 1987. 

Bico fibers are a new class of fibers, rather than a sub-set of PET fibers. Such fibers are formed from two different polymers, which are melted separately, and then combined into a single fiber at the last moment before extrusion. In some cases, the fibers are actually extruded separately, and then combined beneath the spinneret while they are still molten, so that they fuse together after spinning. 

Fot the producer of fibers vdio uses tlus process, the trouble begins with astrong drop of the mdt viscosity % due to the lower molecular weight and the intrinac viscosity of the polymer. Since, for regular spinning of PET, it is a requirement that melt viscosity should not be less than 1000 at 280 °C, a process othor than that based on the decrease of molecular weight may be mme convenient. 

Figure 12.7 Schematic of the melt-spinning process used to produce PET fibers...

The melt spinning process for PET fibers can be divided into three regions of take-up speed, as follows ... 

This article is an overview of the novel technology of self-reinforced LCPs with polyesters, poly(ethylene terephthalate) (PET) and poly(ethylene naphtha-late) (PEN) [10-13, 21, 23], LCP/polyester blends in a polyester matrix form in situ fibrils which improve the mechanical properties. LCPs have an inherently low melt viscosity, and provide LCP/polyester blends that effectively lower the melt viscosity during melt spinning [24], and fast injection-molding cycles. The miscibility between the LCP and polyesters can be controlled by the degree of transesterification [25] in the reactive extrusion step, and fibril formation in LCP-reinforced polyester fibers has been studied. 

Commercial PET has a melting point of about 270°C. Thus, a fiber is produced from the bulk resin by melt spinning into a dry inert gas using a melt temperature of 280-300°C (Fig. 21.1). Fabrics woven from PET resin fibers include the well known Dacron, Fortrel, Crimplene, and Trevira trade names. Although fibers dominate PET processing, a substantial fraction is also blow... 

Ternary blends from a thermotropic liquid crystalline polymer, PEN, and PET were prepared by melt blending and melt spinning to fibers. The mechanical properties of ternary blend fibers could be significantly improved by annealing at 180°C for 2 h. This is attributed to the development of more ordered crystallites and to the formation of more perfect crystalline structures. The interfacial adhesion between PEN and liquid crystalline polymer phases is enhanced when the blends are processed with dibutyl-tindilaurate as a reactive catalyst to promote transesterification. 

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