Multifilament solution

Early in the manufacture of PP, a concept was developed for dry spinning directly from the solution obtained in the polymerization operation. Had it been feasible, it would have been the realization of a chemical engineer s dream the gaseous olefin fed into one end of the equipment, and the packaged fiber, ready for shipment to a textile mill, coming out the other end. But it did not turn out that way, and today melt spinning is the accepted technique for the production of staple fibers, monofilament, and multifilament yams. To this usual method have been added the fibrillation and the slit film procedures for producing yams. 

A variation of the torsion pendulum, torsional braid analysis (TBA), utilizes a supported specimen so that the dynamic mechanical properties of a sample can be monitored in the liquid as well as the solid states (1, 2). An inert multifilamented glass braid is impregnated with the sample (usually in its liquid state or in solution). The observed dynamic mechanical properties are relative due to the composite nature and complex geometry of the specimen. 

The manufacture of all man-made fibers involves at least three distinct process steps. The first consists of the production of polymers or polymer derivatives suitable for spinning into fibers. In the second step, or spinning, a polymer melt or solution is extruded under pressure through the appropriate spinneret s orifice(s) to form the fiber or fibers. If only a single fiber is produced from a spinneret, it is referred to as monofilament. Multifilament spinnerets produce yarns. The third step is drawing,... 

Chardonnet, however, has the distinction of being the first to produce multifilament yarns by forcing a cellulose solution through very small holes in a spinnerette and to produce and market rayon. He was awarded the Perkin medal in 1914 for this achievement. 

Cai J, Zhang LN, Zhou JP, Qi HS, Chen H, Kondo T, Chen XM, Chu B (2007) Multifilament fibers based on dissolution of cellulose in NaOHAirea aqueous solution structure and properties. Adv Mater 19 821-825... 

Two metallurgical problems exist. The first is to find a suitable material for the leads which connect to the electrodes, as they must withstand the mechanical flexure of the beating heart. Several stainless steel alloys have been developed. These, available under the trade names Ethicon and Surgaloy, are used in the form of multifilament wires about 0.013 in. in diameter. The second problem relates to electrolysis of the electrodes, as mentioned in Section 1.1. The stimulative signal may be considered as pulsed direct current. As a result, considerable electrolytic action may occur in the electrolyte environment of the heart tissue. It has been reported that stainless steel is eroded very rapidly but that iridium-platinum alloy is quite stable (Rowley, 1963). A possible solution to the problem, in addition to... 

CNTs/PVA mixed solutions and used them for coating five yams including cotton, silk, wool-nylon, polyester, and PP yams. Resistance of the fabricated yams is in the order of kQ/cm. Rui et al. (2012) demonstrated depositing a CNT-polyurethane composite coating on commercial spandex (polyurethane-polyurea copolymer) multifilament yams. A resistance of 10 Q/cm was obtained, with a concentration of CNT in... 

For spinning of the textile PP mono- and multifilaments, the best solution is a laminar crossflow air quench duct with a minimum ratio of air quantity to air velocity. For spinning of fiber staple tows, the crossflowing quench air can be applied for rectangular spinnerets, i.e., inside-to-outside radial quenching, or double-direction turbulence quenching [141]. 

In the wet spinning process, the spinning solution is initially pumped by a precision gear pump through a spinneret into a coagulation bath, which precipitates the polymer to form filaments. At the exit of the coagulation bath, filaments are collected in bundles of the desired thickness. The multifilament bundles are counter-currently washed in successive extraction baths to ranove residual solvent before they are stretched, dried, and heat-relaxed. 

The microstructural constraints of the matrix, in relation to the multifilament structure of the strand (Chapter 2, Figures 2.10 and 2.11) may enhance effects which are not simulated properly in the study of the strength of single fi laments exposed to alkaline solutions. 

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