Chemical modified nylon

Nylon-8 (polycapryllactam, polyoctanamide) n. A nylon made by condensation polymerization from capryllactam. Its low melting temperature (200° C) and high cost of starting materials have limited the utilization of this polymer. It should not be confused with a type of nylon long marketed as Type-8 , which is actually a chemically modified nylon-6/6. 

Polyamide fibers, 19 739-772. See also Synthetic polyamides applications for, 19 765-766 chemical properties of, 19 745-747 cross-section shape of, 19 756 dyeability of, 19 758-760 early reactive dyes for, 9 468-470 electrical properties of, 19 745 manufacture of, 19 748-749 modified nylon-6 and nylon-6,6, 19 760-764... 

Cationic (Basic) Dyes. These water-soluble cationic dyes are applied to paper, polyacrylonitrile (e g. Dralon), modified nylons, and modified polyesters. Their original use was for silk, wool, and tannin-mordanted cotton when brightness of shade was more important than fastness to light and washing. Basic dyes are water-soluble and yield colored cations in solution. For this reason they are frequently referred to as cationic dyes. The principal chemical classes are diazahemi-cyanine, triarylmethane, cyanine, hemicyanine, thiazine, oxazine, and acridine. Some basic dyes show biological activity and are used in medicine as antiseptics. 

The scope of ion-selective electrodes (ISEs) has been greatly enhanced by employing a poly(vinyl chloride) matrix to entangle sensor cocktail materials. Fbr ISFET devices an in situ photopolymerisation of monobutyl methacrylate provides a viable poly(butyl methacrylate) calcium sensor film with good gate adhesion properties. One or more enzymes can be chemically immobilized on modified nylon mesh. The resultant matrices are suitable for the amperometric assay of carbohydrates in blood and food products. 

Basic (cationic) dyes. Basic dyes are water-soluble and produce colored cations in solution. They are mostly amino and substituted amino compounds soluble in acid and made insoluble by the solution being made basic. They become attached to the fibers by formation of salt linkages (ionic bonds) with anionic groups in the fiber. They are used to dye paper, polyacrylonitrile, modified nylons, and modified polyesters. In solvents other than water, they form writing and printing inks. The principal chemical classes are triaryl methane or xanthenes. Basic brown 1 is an example of a cationic dye that is readily protonated under the pH 2 to 5 conditions of dyeing [5]. 

The world textile industry is one of the largest consumers of dyestuffs. An understanding of the chemistry of textile fibers is necessary to select an appropriate dye from each of the several dye classes so that the textile product requirements for proper shade, fastness, and economics are achieved. The properties of some of the more commercially important natural and synthetic fibers are briefly discussed in this section. The natural fibers may be from plant sources (such as cotton and flax), animal sources (such as wool and silk), or chemically modified natural materials (such as rayon and acetate fibers). The synthetic fibers include nylon, polyester, acrylics, polyolefins, and spindex. The various types of fiber along with the type of dye needed are summarized in Table 8.2. 

Fibre choices for thermal protective clothing include inherently flame resistant (FR) fibres such as the meta- and para-aramids, polyamide-imide, polybenzimidazole, modacrylic and chemically modified fibres such as viscose and modal, polyester, and nylon, as well as FR treated or finished cotton and wooP"" (see also Chapter 8). The... 

Polyamides such as PA6 are engineering thermoplastics with high heat and solvent resistance properties and hence make ideal thermoplastic matrix candidates of choice to make high-performance TPVs with dynamically vulcanized mbber blends. Although nylon blends with low rubber content have been known for a long time as impact-modified nylons, as discussed under Sect. 19.7.1, elastomeric TPV blends of polyamide with high rubber content (>60 %) have not been commercially available until recently. Because of their higher thermal and chemical resistance performance, the polyamide-based TPVs have often been called super-TPVs (Leaversuch 2004). 

The natural polymers mentioned above are synthesized and grown into fibers by nature. Cotton, wool and silk are some examples. Wood is produced similarly, but not being in a form suitable for use as a textile fiber, it must be chemically modified to produce an appropriate solution, which can then be extruded into a fiber. Rayon and cellulose acetate are examples of this pro-cess.1 Synthetic materials, on the other hand, must be first polymerized into chains, by finking small molecules together end to end, and then extruded into fibers. Chains are built by either a condensation or an addition process. Nylon and polyester are examples of polymers synthesized by condensation, whereas polyethylene, polypropylene, acrylic and polytetrafluoroethylene (Teflon ) are some examples of polymers prepared by the addition process. 

The history of thermoplastic polyester goes back to 1929 with the pioneering work of Carothers. The first aromatic polyester of importance is poly(ethylene terephthalate) commonly abbreviated PET (or PETE) and was prepared by Whinfield and Dickson. In 1941, they created the first polyester fibers called Terylene and first manufactured by Imperial Chemical Industries (ICI). PET was produced commercially in 1953 as fiber for textile industry (Dacron) by Dupont using modified nylon technology. Dupont polyester research rapidly leads to a whole range of trademarked products as Mylar, a strong polyester film. 

In this survey, commercially important textile fibers are grouped by their origin. First there are the natural fibers from plant sources, cotton and flax, and those from animal sources, wool and silk. A second group consists of those fibers that are regenerated or chemically modified natural materials—the rayon and acetate fibers. The final group consists of the synthetic fibers, which include nylon, polyester, acrylics, polyolefins, and spandex. 

Nylon. Nylons comprise a large family of polyamides with a variety of chemical compositions (234,286,287). They have excellent mechanical properties, as well as abrasion and chemical resistance. However, because of the need for improved performance, many commercial nylon resins are modified by additives so as to improve toughness, heat fabrication, stabiUty, flame retardancy, and other properties. 

Acid Dyes. These water-soluble anionic dyes ate appHed to nylon, wool, sUk, and modified acryHcs. They ate also used to some extent for paper, leather, food, and cosmetics. The original members of this class aU had one or mote sulfonic or catboxyHc acid groups in thein molecules. This characteristic probably gave the class its name. Chemically, the acid dyes consist of azo (including preformed metal complexes), anthraquiaone, and ttiaryHnethane compounds with a few azHie, xanthene, ketone imine, nitro, nitroso, and quHiophthalone compounds. 

Blends based on polyolefins have been compatibilized by reactive extrusion where functionalized polyolefins are used to form copolymers that bridge the phases. Maleic anhydride modified polyolefins and acrylic acid modified polyolefins are the commonly used modified polymers used as the compatibilizer in polyolefin-polyamide systems. The chemical reaction involved in the formation of block copolymers by the reaction of the amine end group on nylon and anhydride groups or carboxylic groups on modified polyolefins is shown in Scheme 1. 

Many brilliantly coloured and tinctorially strong basic dyes for silk and tannin-mordanted cotton were developed in the early decades of the synthetic dye industry. Most of these belonged to the acridine, azine, oxazine, triarylmethane, xanthene and related chemical classes their molecules are usually characterised by one delocalised positive charge. Thus in crystal violet (1.29) the cationic charge is shared between the three equivalent methylated p-amino nitrogen atoms. A few of these traditional basic dyes are still of some interest in the dyeing of acrylic fibres, notably as components of cheap mixture navies and blacks, but many modified basic dyes were introduced from the 1950s onwards for acrylic and modacrylic fibres, as well as for basic-dyeable variants of nylon and polyester [44] ... 

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