Fiber of polyethylene

In our surface photografting research we have developed two new processes applied to sheets, films and fibers of polyethylene (PE), polypropylene (PP) and poly(ethylene-terephthalate) (PET). 

Du Pont does not currently market Permasep permeators for gas separations. They did, however, in the B-1 Permasep permeator, introduce the first commercial, hollow fiber permeator for gas separations. This permeator employed hollow fibers of polyethylene terephthalate as the membrane. Later, permeators having aramid hollow fiber membranes were field tested for hydrogen separations. Du Pont is presently actively engaged in research for the development of membrane technology for a wide variety of applications. 

Pak J, Wunderlich B (2004) Reversible Melting of Gel-spun Fibers of Polyethylene. Thermochim Acta 421 203-209. 

When a concentrated solution of high molecular weight polyethylene is subjected to high shear at temperatures just above its quiescent crystallization temperature, fibers of polyethylene precipitate. When dried and viewed under the electron microscope these fibers are found to have a shish kebab structure, as shown... 

Figure 4.10 Crystal structure of polyethylene (a) unit cell shown in relation to chains and (b) view of unit cell perpendicular to the chain axis. [Reprinted from C. W. Bunn, Fibers from Synthetic Polymers, R. Hill (Ed.), Elsevier, Amsterdam, 1953.]...

A review covers the preparation and properties of both MABS and MBS polymers (75). Literature is available on the grafting of methacrylates onto a wide variety of other substrates (76,77). Typical examples include the grafting of methyl methacrylate onto mbbers by a variety of methods chemical (78,79), photochemical (80), radiation (80,81), and mastication (82). Methyl methacrylate has been grafted onto such substrates as cellulose (83), poly(vinyl alcohol) (84), polyester fibers (85), polyethylene (86), poly(styrene) (87), poly(vinyl chloride) (88), and other alkyl methacrylates (89). 

Polyethylene. Traditional melt spun methods have not utilized polyethylene as the base polymer because the physical properties obtained have been lower compared to those obtained with polypropylene. Advances in polyethylene technology may result in the commercialization of new spunbonded stmctures having characteristics not attainable with polypropylene. Although fiber-grade polyethylene resin was announced in late 1986 (11,12), it has seen limited acceptance because of higher costs and continuing improvements in polypropylene resin technology (see Olefin POLYMERS, POLYETHYLENE). 

Chemical Hazards. Chemical manufacturers and employees contend with various ha2ards inherent ia productioa of evea commonplace materials. For example, some catalysts used ia the manufacture of polyethylene (see Olefin polymers) ignite when exposed to air or explode if allowed to become too warm the basic ingredient ia fluorocarboa polymers, eg, Tefloa (see Fluorine compounds, organic), can become violently self-reactive if overheated or contaminated with caustic substances (45,46) one of the raw materials for the manufacture of acryflc fibers (see Fibers, acrylic) is the highly toxic hydrogen cyanide (see Cyanides). 

An explosion and fire (March 13, 1991) occurred at an ethylene oxide unit at Union Carbide Chemicals Plastics Co. s Seadrift plant in Port Lavaca, TX, 125 miles southwest of Houston. The blast killed one, injured 19, and idled the facility, that also produces ethylene, ethylene glycol, glycol ether ethanolamines, and polyethylene. Twenty-five residents were evacuated for several hours as a safety precaution. The plant lost all electrical power, for a few days, because its cogeneration unit was damaged. The Seadrift plant, with 1,600 workers, is capable of making 820 million lb per year of ethylene oxide which is one-third of Carbide s worldwide production of antifreeze, polyester fibers, and surfactants Seadrift produces two thirds of Carbide s worldwide production of polyethylene. 

The major uses of ethylene and propene are as starting materials for the preparation of polyethylene and polypropylene plastics, fibers, and films. These and other applications will be described in Chapter 6. 

Fiber glass provides effective inhibition of polyethylene thermal destruction up to 400°C. The inhibitive efficiency increases with increased content of sodium oxide from 0.7-16% (Table 5). 

A similar situation is observed when studying the effect of temperature on inhibition of thermal destruction of polyethylene by fiber glass of varying composition (Table 6). The molecular weight of polyethylene is practically unchanged when exposed over a period of 6 hours at 350°C with 30% of fiber glass containing 16%... 

Indicate, if known, preferred bag material that will withstand environment, e.g., fibers of glass, polyester, Teflon , Nomex , polypropylene, polyethylene, cotton, wool, nylon, Orion , Dacron , and Dynel . The type of weave of fiber should be recommended by the manufacturer. The fabrics may be felted or woven [47,48] in weaves of plain, satin, or twill, and should be resistant to any corrosive material in the solid particles or the gas stream. 

The most generally useful polyester is that made by reaction between dimethyl terephthalate (dimethyl 1,4-benzenedicarboxylate) and ethylene glycol (1,2-ethanediol). The product is used under the trade name Dacron to make clothing fiber and tire cord and under the name Mylar to make recording tape. The tensile strength of polyethylene terephthalate) film is nearly equal to that of steel. 

The two-phase morphologic structure has also been observed in the electron micrographs of polyethylene films and fibers obtained by orientational crystallization16 in which the amount of ECC was approximately 15 to 20% (the fraction of ECC in Porter s samples47 was 17 to 25%). 

Lower-density E-plastomers have found alternate use in cast film processes to make elastic film laminates with good breathability which contain laminates of liquid impermeable extensible polymeric films with extensible-thermoplastic-polymer-fiber nonwovens and nonwoven webs of polyethylene-elastomer fibers as the intermediate layers. The development relates to a breathable film including an E-plastomer and filler that contributes to pore formation after fabrication and distension of the film. The method and extent of distension is designed to produce a breathable film by stretching the film to form micropores by separation of the film of the E-plastomer from the particulate solids. This film is useful for manufacture of absorbent personal-care articles, such as disposable diapers and sanitary napkins and medical garments. In detail, these constructions comprise a liquid impermeable extensible film comprising polyolefins. The outer layer contains extensible-thermoplastic-polymer-fiber nonwovens, and an elastic intermediate layer contains nonwoven webs of fiber E-plastomers. The intermediate layer is bonded to the film layer and the outer... 

Figure 5. ESCA spectra of polyethylene film (PE) and polyethylene fiber (split film PE-F) after grafting for 2 min. with the vapor phase method.

Figure 8.28. Demonstration of a CDF. Data recorded during non-isothermal oriented crystallization of polyethylene at 117°C. Surface plots show the same CDF (a) Linear scale viewed from the top. (b) Linear scale viewed from the bottom, (c) Viewed from the top, logarithmic scale. Indicated are the determination of the most probable layer thickness, lt, and of the maximum layer extension, le. (d) Viewed from the bottom, logarithmic scale. The IDF in fiber direction is indicated by a light line in (a) and (b) (Source [56])...

Polymerization reactions. Polymerization of ethylene to polyethylene has been conducted at pilot-plant scales reaching a target of 1500 tons per year. Some reactions, including polymerization and copolymerization of polymers for grafting on textile fibers, have been successfully performed. Similarly, cross-linking of polyethylene to improve thermal properties has also been achieved. 

In a recent study, Jin and Kaplan (2003) demonstrate the formation of silk fibroin aggregates in the presence of polyethylene glycol, and present a step by step model for fiber formation based on the principle of micelle formation, and driven by dehydration as well as flow elongation. During this process, hydrophobic chains are exposed to the solvent, but because of the molecules high free energy, water solvation is unfavorable and phase separation followed by aggregation predominates. 

In the cavernous halls of the Shanghai Industrial Exhibition, one can see a cornucopia of consumer goods (clothes of polyester, polyacrylic, and polyvinyl alcohol fiber shoes and sandals of polyvinyl chloride suitcases and television set frames of acrylonitrile-butadiene-styrene plastic toys and containers of polyethylene, and many other plastic products (China produced approximately 800,000 tons of plastics in 1980) of convenience we take for granted in the West) that the Chinese government will try to deliver, in quantity, to its citizens in the years to come. 

Fig. 19. Recrystallization of arborescent graft polyethylenes from dense packing of spheres to fibers of linearly aligned molecules upon annealing...

Nardin M. and Ward, I.M. (1987). Influence of surface treatment on adhesion of polyethylene fibers. Mater. Sci. Technol. 3, 814-826. 

Ladizesky and Ward (1983, 1989), Ward and Ladizesky (1986) and Ward (1993) reported that plasma treatment of polyethylene fibers in an atmosphere of oxygen is the most effective among the many techniques studied. There are four major mechanisms responsible for improved fiber-matrix interface adhesion ... 

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