Drawing and Annealing

Lower-denier polypropylene may be draw-textured on conventional draw-texturing machines, which were developed for polyester. On these machines, undrawn yarns are creeled and fed by a roller system to a heated plate. The yarns are drawn and twisted simultaneously 

Heavier-denier BCF yarns are generally spun for tufted or woven carpeting. Typical processes for producing BCF yarns consist of means for drawing the yam coupled with a stream or hot-air jet-texturing device for imparting bulk. The bulked yarn is removed from the jet-crimping device and wound onto a disposable tube. There are many variations of the BCF process. 

There are variations of the spinning process that have not been mentioned here, e.g., bicomponent spinning. Usually, this operation is carried out by employing two extrusion systems that keep the resins separate until just before the streams exit the spinneret. Sheath-core or side-by-side yarns can be spun by this process. Simpler bicomponent yarns are spun with mixed incompatible resins from mixed-pellet blends. 

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Copolymers I-III were extruded into monofilaments and the tensile properties after drawing and annealing are shorn in Tables II and III. The reported data indicate that copolymeric monofilaments can be made to have equivalent or higher tensile strength as con ared with those made from PDS. 

The dimensional stability of the oriented polymer depends on its thermal history, which changes the crystallinity and free volume in the oriented material. Increased draw and annealing temperatures can be used to improve dimensional... 

A number of investigators have performed drawing and annealing experiments on acrylic polymers, copolymers, and fibers that provide support for a limited two-phase model of the structure [143,149-153]. Hinrichsen and Orth [149], for example, have observed periodicities on the order of 120-105 A in the small-angle x-ray pattern of drawn films of the PAN homopolymer. These observations strongly suggest the presence of a two-phase structure, perhaps with lamellar crystalline units, separated by less-ordered material of the chain-folded lamellae [154]. Hinrichsen [143] has observed a similar behavior in drawn PAN fibers. 

Baba, A. Ikezaki, K. "Drawing and annealing effects on thermally stimulated currents in polypropylene films",J. Appl. Phys.Vol. 72, No.5, pp.2057-2059, (1992)... 

Journal of Polymer Science Polymer Physics Edition 36, No.14, Oct.l998,p.2471-82 STRUCTURAL ANALYSIS OF POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE) FIBERS PREPARED BY DRAWING AND ANNEALING PROCESSES Furuhashi Y Ito H Kikutani T Yamamoto T Kimizu M Cakmak M... 

Furuhashi Y, Imamura Y, Jikihara Y, Yamane H (2004) Higher order structures and mechtmical properties of bacterial homo poly(3-hydroxybutyrate) fibers prepared by cold-drawing and annealing processes. Polymer 45 5703-5712... 

Yamamoto T, Kimizu M, Kikutani T, FirruhasM Y, Cakmak M (1997) The effect of drawing and annealing conditions on the structure and properties of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fibers. Int Polym Process XII 29-37 Yamrme H, Terao K, Hiki S, Kimirra Y (2001) Mechanical properties and higher order structure of bacterial homo poly(3-hydroxybutyrate) melt spun fibers. Polymer 42 3241-3248... 

PPS fibers can be manufactured by melt spinning. A further enhancement of the tensile properties can be achieved by drawing and annealing [63]. 

Also, the effect of one-zone draw annealing has been studied [64]. The optimum drawing temperature is around 95 °C. However, the routes for achieving fibers with optimum tensile properties are different for resins with different molecular weights. Two-zone drawing and annealing improves significantly the drawability of PPS fibers and enhances the tensile properties [65]. 

Gulgunje P, Bhat G, Spruiell J. Structure and properties enhancement in poly(phenylene sulfide) melt spun fibers. III Effect of two zone drawing and annealing. J Appl Polym Sci 2012 ... 

Evidences of the occurrence of chemical interactions can be found also in the DSC traces of the PET/PA 6 blend. Fig. 2 shows curves of the second melting of blends crystallized from the melt of isotropic polymers and then subjected to zone drawing and annealing at different T and tg. ... 

Xu, G., Du, Q. and Wang L., Hard elasticity of polyethylene formed by cold-drawing and annealing, Makromol. Ghem., Rapid Gommun., 198 8,... 

Chlorosulfonic acid was used to show the lamellar structure in both linear and branched PE and to study the effects of drawing and annealing [122, 136, 137]. Dlugosz et al [138] examined cryosections of drawn, rolled and annealed, bulk oriented PE which clearly showed a lamellar texture. Lamellae were shown to have two preferred orientations and to be arranged in... 

For certain polymers, biaxial stretching produces microscopic tears throughout the membrane, which imparts a suitable microporous structure. For example, FTFE membranes are used in the Gore-Tex (two-layer and three-layer laminates). The thin microporous membrane is made from a solid PTFE sheet by a novel drawing and annealing process. In drawn form, the tensile strength is increased threefold. The manufacturers claim that these PTFE membranes... 

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