Fiber Blends

Polymer Applications. The reaction of sahcylaldehyde with poly(vinyl alcohol) to form an acetal has been used to provide dye receptor sites on poly(vinyl alcohol) fibers (89) and to improve the light stabihty of blend fibers from vinyl chloride resin and poly(vinyl alcohol) (90) (see Fibers, POLY(VINYL alcohol)). ... 

In the calendering method, a PVC compound which contains plasticizers (qv) (60—120 phr), pigments (qv) (0—10 phr), fillers (qv) (20—60 phr), stabilizers (10—30 phr), and other additives, is kneaded with calender roUs at 150—200°C, followed by extmsion between clearance-adjusted roUs for bonding onto the substrate. This method is employed for products with thick PVC layers, ie, of 0.05—0.75 mm thickness. The main plasticizer used is di-2-ethylhexyl phthalate (DOP). For filler to reduce cost, calcium carbonate is mainly used. A woven or knit fabric made of cotton, rayon, nylon, polyester, and their blend fiber is used as substrate. For foamed vinyl-coated fabrics, the bonded materials are heated in an oven to decompose the foam-blowing... 

The woolen processor is relatively close to the consumer market. The essence of its success is the identification of lucrative markets in apparel or home finishings and the appropriate choice of the most cost-competitive blend fiber input. Technical experience, skillful design, and effective marketing are mandatory. 

Other fibers blended with polyesters in numerous blended fabrics requke alternative methods of preparation. Generally, the scouring and bleaching procedures used for these blends are those employed for the primary component of the blended fiber or for the component that most influences aesthetic appearance. 

Figure 4 SEM photographs of fractured surfaces of PEI-TLCP blend fibers at the draw ratio of 1 (x 3000). The samples were fractured after freezing in liquid nitrogen. The amount of PEsl in the blends are (A) 0 phr, (B) 0.75 phr, (C) 1.5 phr, (D) 2.25 phr, (E) 3.75 phr, and (F) 7.5 phr. Source Ref. 11.

Figure 14 SEM photographs of fractured surfaces of non-elongated nylon 46-Vectra B (75 25 wt ratio) blend fibers. (A) 2.7 wt% SA-g-EPDM was added. (B) No compatibilizer was added. Source Ref. 57.

Figures 20.13 and 20.14 describe the effect of dibutyltin dilaurate (DBTDL) on the tensile strength and tensile modulus for the 25/75 LCP/PEN blend fibers at draw ratios of 10 and 20 [13]. As expected, the addition of DBTDL slightly enhances the mechanical properties of the blends up to ca. 500 ppm of DBTDL. The optimum quantity of DBTDL seems to be about 500 ppm at a draw ratio of 20. However, the mechanical properties deteriorate when the concentration of catalyst exceeds this optimum level. From the previous relationships between the rheological properties and the mechanical properties, it can be discerned that the interfacial adhesion and the compatibility between the two phases, PEN and LCP, were enhanced. Hence, DBTDL can be used as a catalyst to achieve reactive compatibility in this blend system. This suggests the possibility of improving the interfacial adhesion between the immiscible polymer blends containing the LCP by reactive extrusion processing with a very short residence time.

Figure 20.15 SEM fractographs of the LCP/PEN blend fibers after Instron tensile tests (a) 10/90 (wt%) (b) 25/75 (wt%) [13]. From Kim, S. H., Hong, S. M., Hwang, S. S. and Yoo, H. O., J. Appl. Polym. Sci., 74, 2448-2456 (1999), Copyright (1999, John Wiley Sons, Inc.). This material is used by permission of John Wiley Sons, Inc...

Solution blends of 20-25% by weight were formed in DM Ac, with conventional dry spinning and film casting techniques used to produce blend fiber and film, respectively. Blend powders were prepared by precipitating the dope with a non-solvent (water). All materials were extensively washed in methanol or water to reduce residual solvent to less than 1 wt %. Neat resin tensile bars and plaques were compression molded from both powder and fiber. 

The above qualitative picture will be applied to the analysis of a model system, normal alkanes, as a test and then we will proceed to consideration of blends of PSAN and PMMA, a study of plasticized PVC, an example of cross relaxation in PVF2 - PMMA blends and finally a brief examination of blended fibers of PE and PP. 

Figure 16. Comparison of T, data for blended fibers with pure PE (----------) and...

Fiber blending is a very common method of reducing the flammability of flammable fibers. Polyester is usually blended with cotton and this polycotton, if has lower than 50% polyester content can pass the simple vertical strip flammability test. With higher polyester content, sometimes the blended fiber is more flammable than the individual components. This is called wicking effect where the cotton acts like a wick, holding the polyester component together, which bums. Cotton-nylon blend are also quite commonly used to reduce flammability of cotton. 

By contrast, the immiscible lignin/PP blend fibers form unique core/shell structure due to the difference... 

Fig. 10 TGA curves of thermo stabilized HKL and all PP/HKL blend fibers. (A) HKL/PP blend fibers and (B) HKL/PP thermostabilized fibers.

MORPHOLOGICAL CHANGES OF HKL/PP BLEND FIBERS IN THE THERMOSTABILIZATION PROCESS... 

Kenawy et al. studied the potential of electrospun fiber mats as drug delivery system for the release of tetracycline hydrochloride (Kenawy et al. 2002). Electrospun PEVA + PLA blended fibers were 1—3 pm in diameter while the PLA fibers were around 3-6 pm. Srinivasan and Reneker 1995 examined the crystal structure and morphology of the electrospun Kevlar fibers (Srinivasan and Reneker 1995). Fibers from 40 nm to a few hundreds of nanometers were produced. 

Hirano, S. and Zhang, M. 2000. Cellulose-acidic glycosaminoglycan blend fibers releasing a portion of the glycosaminoglycans in water. Carbohydr. Polymers 43, 281-284. 

Grescolev. [Gresco Mfg.] Leveling and compatibilizing agoit for dispersed and acid dyeings on blended fibers. 

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