Nonwoven constructions

A fibrous material extensively used in RPs is the mat constructions. It consists of different randomly and uniformly oriented products  

1 chopped fibers with or without carrier fibers or binder plastics 

2 short fibers with or without a carrier febric 

3 swirled filaments loosely held together with a plastic binder 

4 chopped or short fiber with long fibers included in any desired pattern to provided addition mechanical properties in specific directions 

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Vinyl acetate [108-05-4], (VAc), CH2=CHOOCCH, the ethenyl ester of acetic acid, is primarily use for the manufacture of poly (vinyl acetate) [9003-20-7] (PVAc) and vinyl acetate copolymers. Poly(vinyl acetate) homo- and copolymers are found as components in coatings, paints and sealants, binders (adhesives, nonwovens, construction products, and carpet-backing), and miscellaneous uses such as chewing gum and tablet coatings. Applications have grown over the years in a number of areas (1—4). 

Many film adhesives have a supporting carrier or reinforcement fabric incorporated into the adhesive to improve handling of the film and provide control of bond line thickness. The carriers are usually glass, polyester, or nylon fabrics of knitted, woven, or nonwoven construction. The difficulty with such carriers is that they can provide an effective way of moisture entering the bulk of the adhesive. Moisture can wick along the fiber-adhesive interface. Nylon carriers should especially be reviewed since they have a strong tendency to absorb moisture. 

Nonwoven products for use in civil construction amounted to 1.4% in 1985 and increased to 2.3% in 1995. In 1995, about 196 KT of nonwoven construction fabrics were consumed in the United States, 140 KT in West Europe, and 15 KT in Japan. Its market share is estimated to increase to 3.5% by 2005. This growth has been attributed to the wide adoption of nonwoven products in engineering projects on rocky grounds. 

The second group within this area comprises protective clothing such as cut resistant gloves and slash resistant trousers for industrial use. Since the aspect of stab resistance is not a significant feature of this technical requirement, then these applications are satisfied by woven, knitted, and nonwoven constructions and composites based on para-aramid, UHMW polyethylene, PBO, and similar fibres. 

Filter-medium selection embraces many types of construction fabrics of woven fibers, felts, and nonwoven fibers, porous or sintered solids, polymer membranes, or particulate solids in the form of a permeable bed. Media of all types are available in a wide choice of materials. 

Other than the processes mentioned here, natural fibers are used as construction units, by applying hybrid nonwovens, i.e., natural fiber staple fiber fleece [6I]. 

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... 

In flame retarding nonwovens, the contribution of components may not be additive. Rather, the interaction of binder, flame retardant, and substrate is critical in the performance of the flame retardant nonwoven. Similarly, the flammability of a binder film or the flammability of a flame retardant coated woven cloth often do not predict the flame retardancy of the same binder or flame retardant on a nonwoven substrate of rayon or polyester. Actual data on a nonwovens substrate is the only accurate measure of a system s flame retardancy. For this study, two widely used substrates were selected. The first, lightweight rando rayon, is representative of material used in nurse caps, surgeon s masks, and miscellaneous coverstock. This material is constructed of 1 1/2 denier fiber, weighs 1 1/2 ounces per square yard, and is relatively dense web. Rayon as a material is water absorbent, burns rather than melts, and is readily flammable. This fiber ignites around 400°C(2) and has an oxygen index of about 19.0. Certain binders adhere well to rayon while others do not. Apparently, this lack of affinity for the substrate affects flame retardancy, as will be demonstrated later. 

In Sections 24.3 and 24.5 the flammability and fire resistance of individual fiber/fabric type are discussed. However, as also discussed before, the fire resistance of a fabric not only depends upon the nature of components and the FR treatments applied, but also on fabric area density, construction, air permeability, and moisture content. Nonwovens, for example, will have superior properties to woven or knitted structure, even if all other variables are kept the same.93 The air entrapped within the interstices of any fabric structure and between layers of fabrics within a garment assembly provides the real thermal insulation. For effective thermal and fire resistance in a fabric structure, these insulating air domains need to be maintained.22 In general, for protective clothing and fire-block materials, for best performance multilayered fabric structures are employed. The assembly structures can be engineered to maximize their performance. It is beyond the scope of this chapter to go into details of these composite structures hence the reader is referred to the literature on specified applications and products available. 

Bostik, Inc., formerly Bostik Findley, Inc., is a leading global producer of adhesives and sealants. The firm operates in five segments construction and distribution performance adhesives nonwovens/tape and label global transportation and flexible laminating. The construction and distribution division manufactures flooring installation adhesives for tile, stone, hardwood, carpet and vinyl caulks, elastic adhesives, aerosol adhesives, fire-retardant adhesives, epoxies,... 

The most widely used alternative approach in layer construction involves trapping components in a preformed matrix by saturation techniques. In this approach, the matrix of choice is saturated vdth a solution of desired components or reagents. Commonly used preformed matrices include paper, woven fabrics, nonwoven fabrics, and a variety of porous membranes. The availability... 

In the submicron range of particle sizes, there are at least two media types to consider depth and microporous membrane. Typically, depth media is melt-blown fibrous nonwoven type (Fig. 18.13). Membranes are basically cast or expanded microporous films. Depth filters with a wrapped or pleated construction are used for slurry filtration (see Fig. 18.14a and b). Membrane... 

Nature of textile Textile construction yarn (staple or filament), fabric (knit, woven or nonwoven)... 

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