Fiber extrusion

Fiber drums, as industrial materials packaging, 18 9-10 Fiber dyebath, damage to, 9 169 Fiber etalons, 11 151, 152 Fiber extrusion, VDC copolymers in, 25 725, 727-728... 

Monofilament fiber extrusion, 79 790 VDC copolymers in, 25 725, 727-728 Monofilament sutures, 24 218 Monofilament suture threads, 24 207 Monofunctional glycidyl ethers, 70 376-377 Monoglycerides, 72 55 melting points of, 70 821 Monohaloalkylations, 72 167 Monohalogenoboranes, 73 636... 

Spinnerets, for olefin fiber extrusion, 22 627, 630-631, 11 231-232 Spinner flasks, 15 691-692 Spinning. See also Solution spinning Yarn spinning technologies air gap, 11 209 of continuous-filament yarns,... 

Spinning basket reactor, 21 352, 353 Spinning-cup atomizers, 23 659 Spinning-cup sulfur burner, 23 660 Spinning machines, 19 749 Spinning processes, hollow-fiber, 16 7-12 Spinning pump, for olefin fiber extrusion, 11 231... 

Polypropylene Resin Injection Molding Fiber Extrusion Sheet Forming Thermoforming... 

Accessible precursor architectures (building imits, dimensionality of the polymer molecule) are dictated by the methods of the chemical synthesis of the monomer units and the associated polymerization reactions. The type of shape-forming procedure used (fiber-extrusion firom solution or melt, spincoating, etc.) engenders constraints on what is considered useful polymer rheology. Especially in the case of fiber-drawing or -extrusion the precursor should exhibit thixotropic or non-Newtonian viscoelastic behavior. The viscosity should be sufficiently high at zero shear such that once formed, the material will retain its new shape. 

Presence of small amounts of isotropic material within the mesophase can have important practical implications in processing of polydisperse samples. We have observed, for example, that upon fiber extrusion from the nematic melt, optimum mechanical strength is not developed until extrusion temperatures are below the l/N transition temperature of the shortest components. Similarly, measurement of order parameter shows that presence of a minor isotropic component deters optimum overall alignment until a temperature some 25-30 C below the transition to a "homogeneous nematic phase, as observed by microscopy. ... 

Nanocomposite fibers have been produced by compounding a semi-aromatic poly(m-xylene adipamide) with an organophilic montmorillonite [61]. Partially oriented fibers of the nanocomposite were obtained by melt spinning on a mulfifilament fiber extrusion system. The effect of the drawing velocity on... 

Figure 3.17 Tensile strength plotted against %Vf cartion liber for aluminum/chopped fiber extrusion. Broken line as predicted by Law of Mixtures. Source Reprinted with permission from Howlett BW, Minty DC, Old CF, The fabrication and properties of carbon fibre/metal composites, Paper No. 14, International Conference on Carbon Fibres and Applications, The Plastics Institute, London, 1971. Copyright 1971, Maney Publishing (who administers the copyright on behalf of lOM Communication Ltd, a wholly owned subsidiary of the Institute of Materials, Minerals Mininng).

Cangle water temperature n. The temperature of the water surrounding the candle filter or within the heating jacket during fiber extrusion. 

While the extruder pumps the molten polymer, the die and downstream equipment determine the final form of the plastic. Blown film and flat film extrusion both produce plastic films, but require very different dies and take-off systems. Similarly, different extrusion lines are used for pipes, tubing, profiles, fibers, extrusion coating, and wire coating. 

The MWD can be made broader by using a two-reactor configuration that produces different melt flow rates in each reactor. Recently, metalloeene PP eata-lysts have shown the ability to produce PPs with very narrow molecular weight distributions, on the order of 2-3. These resins have a great deal of value in fiber extrusion applications where less shear sensitivity of the viscosity is important. 

In some applications, it is actually possible to segregate antagonistic coadditives such as the flame retardant from the stabilizer by coextrusion. For example, bicomponent fiber extrusion is one such application. Figure 4.45 shows a filament cross-section where the flame retardant is restricted to the core whereas the sheath is UV stabilized. Figure 4.46 demonstrates the advantage in UV durability from bicomponent construction. 

Primary concerns in fiber extrusion are the fiber uniformity and avoidance of breaks. Both of these can be traced to an uneven feeding of the polymer through the die. Textured and hoUow fibers can also be produced. 

In fiber extrusion, in particuiar PP, a screen build-up test is used in some cases. This test reflects not just the gel level in the polymer because other materials can be trapped in the screen as well. Also, not all gel particles may be captured in the... 

Pigment-inherent properties, such as heat resistance and chemical inertness to other additives present in PP, have to be considered to achieve color consistency during the whole conversion process. High quality of pigment dispersion is required for film and especially for continuous filament fiber extrusion, to avoid breakage of laments and to ensure process stability. 

Melt Processing. Vinylidene chloride copolsrmers are melt processed via a variety of fabrication techniques. These include molding, monofilament fiber extrusion, monolayer blown film extrusion, multilayer cast- and blown-film extrusion, and multilayer sheet extrusion. There are a number of elements of melt processing and melt-processing equipment that are common to all of these fabrication techniques (184 187). These include proper equipment design and materials of construction, proper and accurately controlled operating conditions, and a properly formulated resin. 

MonofilamGnt Fiber Extrusion. Monofilament fiber extrusion was another early application for VDC resins (184,191,193). Monofilament applications have included automotive seat covers, window screens, and upholstery fabrics, where the durability and ease of cleaning were important. Fabrics made from VDC copolymer monofilaments are still used today in applications such as filter fabrics, light screens, greenhouse covers, pool or bath fabrics, and shoe insoles (194). Such fabrics claim excellent resistance to flame, chemicals, uv light, moisture, and microbial attack. 

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