Polyethylene drawn fiber

There are several interesting applications reported in the literature, such as insulated wire and cable, UV cross-linking of drawn fibers, and tapes from ultra-high-molecular-weight polyethylene. Semi-interpenetrating networks (IPNs) from acrylates and polyurethanes are suitable as UV curable adhesives with high elasticity, good impact resistance, and excellent adhesion to a variety of substrates. ... 

The recent studies of the phase structure of linear polyethylene by refined NMR analyses are reviewed. The phase structure of the polymer in various crystalline forms, including bulk-crystals, solution-crystals and drawn fibers, is discussed in terms of different modes of molecular mobilities in a wide range of temperature. 

White (1955) believes that differential thermal analysis curves obtained by him on heating drawn fibers of 6, 6-6 and 6-10 nylons as well as polyethylene terephthalate, indicate that at first crystallites disorient and then melt. He found two peaks in what would correspond to a specific heat-temperature curve. However, it is difficult to understand why the disorientation of oriented crystals would involve the absorption of energy. 

The three-phase structures 12, 13, and 14 are of particular interest because of the even more severe violation of the phase rule. At constant pressure, in equilibrium, only one-phase areas should be stable. Drawn fibers of poly(ethylene terephthalate) (PET) are discussed as three-phase sttucture with Figs. 5.68-72 and 5.113-115. As in polyethylene, the drawing to fibers or films orients the amorphous nanophase and achieves an arrested mesophase order, proven with Fig. 5.72. Since the drawing of PET fibers is much less efficient in extending the molecules than gel-spinning, there remains a sizeable portion of the amorphous phase, as shown in Fig. 5.71. The mobile mesophase of PET has not been found as a stable phase, as in polyethylene. Copolymers of PET with stiffer repeating units, such as oxybenzoate, however, have stable mesophases (see Chap. 7). 

Some polymer sheets and fibers are prepared in such a way that polymer chains are spatially oriented. The degree of orientation of the polymer chain is related to physical properties. For instance, certain polypropylene and polyethylene films are partially oriented in one direction because of the way the films are drawn during manufacture. Such oriented films may be easily torn to one direction but not the other, or they may preferentially yield to stretch in one direction. In the case of fibers, the drawn fiber is more resistant to yielding from stretching. 

The tensile strength of 10 times one-step-drawn fiber was over 1.0 GPa, which corresponded to those of common plastics such as polyethylene and poly(ethylene terephthalate). The molecular and highly ordered structure of mono-filament was analyzed by a micro-beam X-ray diffraction with synchrotron radiation at SPring-8, Japan. 

Unlike nylon, which in the as-spun state contains a high amount of crystalline component, polyethylene terephthalate fibers are essentially amorphous as spun. In order to secure a usable textile yarn or staple fiber, this product must be drawn under conditions that will result in an increase in both molecular orientation and crystallinity. This is done by drawing at a temperature well above the glass transition point, 7, which is about 80 C. Conditions of rale and temperature must be... 

Fibers are thin threads produced by extruding a molten polymer through small holes in a die, or spinneret. The fibers are then cooled and drawn out, which orients the crystallite regions along the axis of the fiber and adds considerable tensile strength (Figure 31.3). Nylon, Dacron, and polyethylene all have the semicrystalline structure necessary for drawing into oriented fibers. 

Although they have an endless variety of properties, polymers can be divided into three general categories, based on their form and resistance to stretching. These are plastics, fibers, and elastomers. Plastics differ in form from fibers whereas plastics exist as blocks or sheets, fibers have been drawn into long threads. Unlike plastics or fibers, elastomers can be stretched without breaking. Polyethylene packaging films and polyvinylchloride (PVC) pipe are examples of plastics. Orion carpets are made from polymer fibers, and mbber bands are elastomers. Some polymers, such as Nylon, can be formed into both plastics and fibers. 

Other textile fibers such as polyethylene terephthalate came into production first in England and then in America. The English discovered the fiber and the Americans discovered the film. When it was drawn bi-axially, polyethylene terephthalate gave a very good film which has had wide use. 

Ladizesky, N.H. and Ward, I.M. (1983). A study of the adhesion of drawn polyethylene fiber/polymer resin systems. J. Mater.. Sci. 18, 533-544. 

Almost all of these examples involve diffusion of a chemical species measuring diffusion rates has long been a specialty of NMR spectroscopy. The studies of KBr and drawn polyethylene produced unique information in the latter case, the known orientation of the deuterium electric field gradient in C-D bonds is used to determine the orientation, with respect to the magnetic field, of a polymer chain of a uniaxially ordered polyethylene fiber. The real time imaging of the polymerization of methyl methacrylate is very interesting and may represent a major direction for NMR imaging applications to polymer science. 

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