Polypropylene fibers, isotactic

Polypropylene fibers represent a small percent of the total polypropylene production. (Most polypropylene is used as a thermoplastic.) The fibers are usually manufactured from isotactic polypropylene. 

Fig. 12.21. Diagrams showing (a) irregular atactic, (b) stereoregular isotactic, and (c) stereoregular syndiotactic configurations in polypropylene polymer. (Source Ahmed, M., "Polypropylene Fibers-Science andTechnology," Textile Science and Technology, 5, 16, Elsevier Science Publishers SV, Academic Publishing Div., New York, Amsterdam (1982).) Copyright M. Ahmed. By permission.

In some cases, this orientation may be difficult to predict. Thus, a study of the adsorption of a series of w-alkyl sulfates and POE nonylphenols onto isotactic polypropylene fiber and of the washing properties of the same surfactants for the... 

Gownder et al. Reduced shrinkage in metallocene isotactic polypropylene fibers, U.S. Patent... 

Ran, S. et al. (2001). Structural and morphological studies of isotactic polypropylene fibers during heat/draw deformation by in-situ synchrotron SAXS/WAXD. Macromolecules, Vol.34, Issue 8, pp. 2569-2578. 

The addition of an a-nucleating agent increased of crystallinity and slightly decreased the orientation factor melt-spun isotactic polypropylene fibers. An a-phase nucleating agent, Millad 3988 from Milliken Chemicals, was added at a concentration of 150 ppm. ... 

Table 1 Sample details of as-spun isotactic polypropylene fibers...

Isotactic polypropylene, based on the stereospecific polymerization catalysts discovered by Ziegler and Natta, was introduced commercially in the United States in 1957. Commercial polypropylene fibers followed in 1961. The first market of significance, contract carpet, was based on a three-ply, crimper-textured yarn. It competed favorably against wool and rayon-wool blends because of its lighter... 

Fig. 27. Polarized Raman spectra of oriented isotactic polypropylene fibers (22).

Melt flow stndies have been reported on polypropylene [91], isotactic butadiene [92], glass fiber-filled polypropylene [93], and low-density polyethylene [94],... 

Sun X, Li H, Zhang X, Wang D, Schultz JM, Yan S. Effect of matrix molecular mass on the crystallization of -form isotactic polypropylene around an oriented polypropylene fiber. Macromolecules 2010 43 561-564. 

El-Dessouky, H.M., Mahmoudi, M.R., Lawrence, C.A., Yassien, K.M., Sokkar, T.Z.N., and Hamza, A.A., On the Physical Behavior of Isotactic Polypropylene Fibers Extmded at Different Draw-Down Ratios. I. Optical Properties and Cold-Drawing , Polymer Engineering and Science, 49, 2216-2224, 2009. 

Polypropylene (PP) Most applications use the isotactic form. Oriented (OPP) and unoriented films are used often for food packaging, sometimes in eombination with vinylidene chloride copolymers. Polypropylene fibers are used for webbing in outdoor furniture, earpets, and both woven and non-woven fabrics. Polypropylene is also an important engineering thermoplastic. 

Larin B, Avila-Orta CA, Somani RH, Hsiao BS, Marom G (2008) Combined effect of shear and fibrous fillers on orientation-induced crystallization in discontinuous aramid fiber/isotactic polypropylene composites. Polymer 49(l) 295-302... 

The majority of spunbonded fabrics are based on isotactic polypropylene and polyester (Table 1). Small quantities are made from nylon-6,6 and a growing percentage from high density polyethylene. Table 3 illustrates the basic characteristics of fibers made from different base polymers. Although some interest has been seen in the use of linear low density polyethylene (LLDPE) as a base polymer, largely because of potential increases in the softness of the final fabric (9), economic factors continue to favor polypropylene (see OlefinPOLYMERS, POLYPROPYLENE). 

Polypropylene (PP) is a major thermoplastic polymer. Although polypropylene did not take its position among the large volume polymers until fairly recently, it is currently the third largest thermoplastic after PVC. The delay in polypropylene development may be attributed to technical reasons related to its polymerization. Polypropylene produced by free radical initiation is mainly the atactic form. Due to its low crystallinity, it is not suitable for thermoplastic or fiber use. The turning point in polypropylene production was the development of a Ziegler-type catalyst by Natta to produce the stereoregular form (isotactic). 

Polypropylene was not developed until the 1950s when Ziegler and Natta invented coordination catalysts. The structural difference between polyethylene and polypropylene is the methyl group in the propylene unit. Its presence makes a difference because it makes possible three different polymer structures Isotactic, with all methyl groups in the same plane makes the best plastic syndiotactic, in which the methyl groups alternate in the same plane and atactic, with the methyl groups randomly in and out of the plane is soft and rubbery. Polypropylene is used as film and in many structural forms. It is also used as fibers for carpet manufacture and for thermal clothing. 

The intramolecular interaction energy was calculated for five isotactic polymers, namely, isotactic polypropylene, poly(U-methyl-l-pentene), poly(3-methyl-1-butene), polyacetaldehyde, and poly(methyl methacrylate) (23). The molecular structures of the first four polymers have already been determined by x-ray analyses as (3/1) (2k), (7/2) (18,25.,26), (U/l) (21), and (U/l) helices (28), respectively. Here (7/2) means seven monomeric units turn twice in the fiber identity period. For isotactic poly(methyl methacrylate) (29), a (5/l) helix was considered reasonable at the time of the energy calculation in 1970, before the discovering of... 

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