Extruded Fibers

Wu [353] who studied extruded fiber-filled composite samples established that the distribution of fibers along the radius of the specimen depended on the extrusion rate at low rates the fiber distribution is uniform, at medium rates the minimum of filler concentration occurs at 0.63 R (R is the extrudate radius) (in case of spherical particles this point corresponds to the maximum filler concentration) at high extrusion rates most of the fibers are concentrated about the flow axis and there are almost none on the extruded sample surfaces. 

Not many attempts on applying this procedure to organic filaments have been recorded in the literature. In a relatively recent paper55), extruded fibers of paraffin wax were examined and the conclusion was reached that the method was unsuitable for determining the ys of paraffinic solids. 

The extruded fiber is then often uniaxially stretched by take-up rollers rotating at different speeds. The fiber stretching encourages the polymer chains to align on a molecular level producing increased strength in the direction of the pull. 

In the Redaimator, a bigb pressure extruder, fiber-free mbber is heated to 175—205°C with oils and other ingredients. High pressure and shear between the mbber mixture and the extruder barrel walls effectivdy devulcanize the mixture in one to three minutes. In the Lancaster-Banbury method, bigb temperature, pressure, and shear are applied to the mbber in a batch process that is otherwise similar to the Redaimator process. In another high pressure process, scrap mbber is devulcanized at 5.5—6.9 MPa (54—68 atm) for ca five minutes. The product is milled, baled, or pelletized as in other processes. 

The extrusion temperatures of the polymer far below the melting point of the drug. Upon cooling of the extruded fibers, dissolved drugs may either recrystallize or remain soluble, which results in a supersaturated state. The amount of the dissolved drug can be correlated to the release properties. The state in which the drugs are left after extrusion determine their properties of permeation. 

You are to use a square pitch 60 mm diameter extruder to extrude fibers through a spinnerette with 100 capillaries. Each capillary has a 0.2 mm diameter and is 1mm long. 

This work has demonstrated that we have been successful in extruding fibers from these polymer nanocomposites, knit them into textiles, and test their flammability. These prototype nanocomposite FR fiber-forming polymers and textile materials based upon them could be taken forward by interested parties for scale-up and commercial development. 

Strzelecki has studied the orientation of a nematic polymer in its LC state in a 0.3 T magnetic field by X-ray diffraction and found that the sample had an order parameter of 0.64 The orientation of LC polymers in a magnetic field has also been observed by others using X-ray techniques I Extruded fibers have been studied by Roviello and Sirigu to measure the degree of orientation achievable in mesomorphic polymers by shear field, but only solid samples were studied and even though they were oriented, the results gave little quantitative indication of the order of the mesophase... 

Liquid polymers (at ambient temperature) are in general macromolecules with a relatively low molecular weight, many of them being in fact oligomers. Some liquid polymers are utilized as synthetic oils. Certain polymers can form liquid crystals in other words they can have an ordered structure while being in liquid state (either melted or in a solution). The orientation of certain polymeric molecules in liquid state such that the properties of the material are anisotropic is possible. Polymer liquid crystals have practical applications, and solution of liquid crystal polymers can be used for extruding fibers that have a highly crystalline structure after solvent elimination. 

Fibers and hollow fibers made of chitosan and alginate materials are less frequently cited. The preparation of fibers and hollow fibers obeys the same two-step procedure (1) dissolving the biopolymer, followed by (2) the extrusion of the solution into a coagulation bath, as described for gel bead preparation. The fiber is extruded through a thin nozzle into a bath and falls from a spinneret directly into the coagulation bath or alternatively in air to stretch the extruded fiber and reduce its diameter before it enters into the coagulating bath [61]. 

Figure 2. Wide Angle X-ray (WAXS) pattern of 303-50 extruded fiber (right) and of zinc stearate powder (left) (adapted from Ref. 16).

Multifilament cloths are constmcted of a bundle of fibers twisted together. Only synthetic materials are available in this form, since long continuously extruded fibers must be used. Spun fabrics are composed of short sections of bound fibers of varying length. Retention of small particles is increased as the number of fibers or filaments in a bundle increases. The greater the amount of twist in the yam, the more tightly packed the fabric, which contributes to retention. This twist will also increase the weight of the fabric and frequently extends filter cloth lifetime. 

FR-1034 1-Propanol, 3,3 -oxybis(2,2-bis(bromotT ethyl)- TBDPE. Flame retardant for PP extruded fibers processing aid for ABS and HIPS. Powder mp = 75-82 LDso (rat ori) > 5000mg/kg. AmeriHaas Bromine Dead a. 

Starch pyrodextrins and British gums have the ability, in aqueous dispersion, to form films capable of bonding like or unlike materials. Thus, they have uses as adhesives for envelopes, postage stamps, and other products. These dextrins are used in glass-fiber sizing to protect the extruded fiber from abrasion, and as binders for metal core castings, water color paints, briquettes, and many other composite materials (qv). 

At present, hollow-fiber membranes used for gas and liquid separations are mostly prepared from amorphous polymers by means of a phase inversion technique. In this technique, a polymer is dissolved in a suitable solvent or solvent mixtures and spim into a coagulation bath, where solvent exchange occurs between the extruded fiber and coagulant, yielding the asymmetric membrane structure. 

Rat-tail collagen type I extruded fibers tested after stretching from 0 to 50%. 

Finally, many polyphosphazenes have been studied as tbin films, solvent-extruded fibers, and nanofibers by solvent casting, spin casting, solvent extrusion, and electrospinning methods (Figures 7.2 and 7.5). These techniques have proved useful for semi-crystalline fluoroalkojyphosphazene polymers and for arylojy-substituted derivatives. 

LCP characteristics, such as high mechanical properties (strength, modulus), ease of processibility, excellent thermal resistance, low water absorption, and low gas permeability, make LCPs attractive for a wide range of applications. The applications of main-chain LCPs can be divided into several areas extrudates (fibers, rods, sheets) used in the chemical and materials industry, and moldings (chip carriers, connectors, switches) used in microelectronics [6]. 

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