Monofilaments fibers

Analytical determination of the hydraulic resistance of the medium is difficult. However, for the simplest filter medium structures, certain empirical relationships are available to estimate hydraulic resistance. The relationship of hydraulic resistance of a cloth of monofilament fiber versus fiber diameter and cloth porosity can be based on a fixed-bed model. 

In selecting cloths made from synthetic materials, one must account for the fact that staple cloths provide a good retentivity of solid particles due to the short hairs on their surface. However, cake removal is often difficult from these cloths - more than from cloths of polyfilament and, especially, monofilament fibers. The type of fiber weave and pore size determine the degree of retentivity and permeability. The objective of the process, and the properties of particles, suspension and cake should be accounted for. The cloth selected in this maimer should be confirmed or corrected by laboratory tests. Such tests can be performed on a single filter. These tests, however, provide no information on progressive pore plugging and cloth wear. However, they do provide indications of expected filtrate pureness, capacity and final cake wetness. 

Monofilament fibers require special attention to ensure a uniform open space between the filaments. 

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... 

EFFECT OF DRAWING SCHEMES ON TENSILE PROPERTIES OF MONOFILAMENT FIBERS... 

In all cases the anisotropic polymerization mixtures (10% by weight) could be used directly in the formation of dry-jet wet-spun fibers. Monofilament fibers were obtained by coagulation in water, tension dried at 150 °C and heat treated at 500-600 °C with a 30s residence time. The best fibers were obtained from the high molecular weight PBZT polymer (VII) which exhibited modulus values that ranged between 172 GPa and 207 GPa and tenacity values up to 2.4 GPa. Unfortunately, the compressive property as measured by the tensile recoil test was only 380 MPa, showing only a slight improvement over PBZT. 

Table 8-2. Summary of properties of different types of monofilament fibers (Rebenfeld 1986 Smit, Jacobs, and van Dingenen 2003).

Nylon forms only at the interface of the two immiscible solutions because neither of the reagents is soluble in the other solvent. In addition, the nylon polymer is not soluble in either solvent. The rope pulled from the interface is actually a column of nylon filled with solvent and reagents. After washing and drying, the strand is considerably smaller in diameter. It lacks the strength of something like a monofilament fiber because the molecules in our nylon sample have not been oriented by stretching. In addition, the molar mass of our nylon is probably considerably lower than that of a commercial sample. 

Monofilament yarns consist of a single filament. The filament size is much larger than those found in multifilament yarn. Consequently, monofilament is relatively stiff and is used mainly for the production of rope and twine. Fiber size range is typically 75 to 5000 denier. Monofilament fiber is usually produced from polypropylene homopolymer with a relatively low melt flow index in the range 3.5 to 5.0 grams/10 min. 

Available forms Extrusion and molding powder, aqueous dispersion, film, monofilament fiber, and nonsticking finish. 

Industry Specific Technical Guidance Documents for Estimating Releases Monofilament Fiber Manufacture... 

As noted in Section 12.5.1, a family of polyaxial copolyesters described in Chapter 2 can be used to prepare two or more of the critical components of a femoral sealing device. Other compliant members of this family of polymers, which can be converted to compliant, stretchable membranes and strong, stretchable monofilament fibers, can be used to construct a mantle or cover for metallic endovascular stents. Thus, a composite of thin film, reinforced with a monofilament in cross-coiled configuration, can be assembled into a highly compliant, expandable, tubular mantle or sleeve. This can be placed tightly as a cover outside an expandable metallic or polymeric stent so that under concentric irreversible expansion at the desired site of... 

Most CMCs are reinforced with continuous, multifilament tow ceramic fibers. Fiber tows typically consist of 500 to 1,000 filaments, with a diameter of 10 to 15 pm (0.40 to 0.59 mils) each. These fiber tows are flexible, easy to handle, and can be woven into fabrics and used to fabricate complexshaped composites. Monofilament fibers have also been used to reinforce ceramic composites, but they have several disadvantages. For example, monofilaments (espeeially singleerystal fibers) are expensive, and their large diameter (> 75pm [3.0 mils]) limits their minimum bend radius, whieh ean make fabricating complex-shaped composites difficult. This chapter, therefore, focuses on small diameter, multifilament eeramie fibers. 

Uses Gas and moisture barrier food-pkg. film flexible pkg. films monofilament fibers in resinous/polymeric food-contact coatings in paper/paperboard in contact with aq./fatty foods in cellophane for food pkg. food-contact surfaces... 

The melt-spun monofilament fibers from this triblock material were achieved at temperatures about 10-40°C above the corresponding melting temperatures of the copolymers. An in vivo implantation study of a triblock copolymer fiber (of 5/5/90 feed ratio) in rat up to 240 days showed that the monofilament fibers were morphologically intact at 120 days but fragmented at 150 days. Complete mass absorption was achieved at 240 days in rats which is consistent with the reported complete mass absorption for pure PDS sutures. The tissue reaction observed was typical... 

Table 14.9 Properties of Monofilament Fibers Derived from the Carbide and Nitride of Silicon...

Fibers have many features that could be advantageously used in implantable textile medical device design to confer them specific properties. However, expected to monofilaments, fibers generally need to be assembled within the stracture to be exploited. Cohesion is needed to withstand the textile process and/or handling. 

Two, 2 cm, segments of monofilament fiber ha dng a diameter corresponding to size 2-0 suture were implanted aseptically into the left gluteal muscles of 24 female Long Evans rats. The implant sites were recovered after periods of 60, 90, 120 and 180 days and examined microscopically to determine die extent of absorption. After 60 days the suture cross-sections were still transparent and intact. The tissue reactions were slight and most sutures were encapsulated with fibrous tissue. 

The inherent flexibility of poly(p-dioxanone) allows it to be fabricated into a monofilament fiber useful for all sizes of sutures. Poly(j>dioxanone) suture has greater pliability than poly(propylene) suture and can provide substantial strength when compared to most other monofilament sutures. 

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. 

Heeger s research group obtained monofilament conductive fibers from a blend of polyaniline and poly(/ -phenyleneterephthalamide) (Kevlar from DuPont) [88]. The monofilament fibers, with different concentrations of polyaniline, were wet-spun from a solution of the component polymers in sulfuric acid, into a 1 N sulfuric acid solution. In the process, a draw ratio of 7 20 and an extrusion speed of 0.12-0.3mmin enabled the continuous production of bobbins. These were sprayed with deionized water to prevent fiber collapse and to remove the excess of sulfuric acid. The bobbins were immersed in HCl to protonate the polyaniline and dried in a vacuum oven. Pure polyaniline fibers were also wet spun by the same method. The Kevlar fibers become brittle with an increase in the concentration of polyaniline. In general, the mechanical properties of the fibers change proportionally to the concentration of polyaniline. Enhancement of the strain at break occurs at the expense of electrical conductivity. The most significant result from this work was the observation that small amounts of polyamide improved markedly the mechanical properties of polyaniline fibers, while retaining its conductivity (10 S cm ). 

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