Spun-Bonding

Nonwoven fabrics are generally described by the method of production, eg, needle-punched or spun-bonded (120). ASTM D1117 discusses various physical properties to be deterrnined for nonwoven fabrics and the standard procedures used. 

One of the important aspects of the development of P-plastomers was the expectation that these materials were amenable to plastics processing such as fiber and film formation and yet would yield soft elastic fabrication. This combination was hitherto unknown [24]. The formation of nonwoven fabrics including spun-bond and melt-blown nonwoven fabrics as well as their laminated forms has been documented. Similarly, cast film operation to form elastic monolithic films or composite structures which are not only amenable to these processes, but also to a variety of postfabrication processes have been described. 

Polymer scientists and engineers have developed a wide variety of processes by which to convert polypropylene into useable articles. These processes include fiber-spinning, production of melt blown and spun bond non-woven fabrics, film production, blow molding, and injection molding. The following sections describe these processes and the resulting properties of the product as a function of the process. 

Melt-Blown and Spun-Bond Non-Woven Fabrics... 

Hot caps, small domes made of translucent paper, may also prevent insects or disease spores from reaching individual plants. Other barriers can protect entire rows of plants. Spun-bonded row covers, for example, can be placed over young plants of the cabbage family to exclnde various cabbage feeding insects, or over cantalonpe and encumbers to keep... 

Some birds also consume vegetables. Do not permit any seed to remain visible on the surface of the ground when planting vegetables. It may also be necessary occasionally to make use of netting or spun-bonded row covers to protect vegetables from birds. Imitation snakes, owls and hawks repel birds only if they are moved frequently from place to place and then only for a short time. Plastic foam cups inverted over com ears after pollination may protect ripe com ears from blackbirds. 

Subcategories Spun bond Free-standing Foams oxide ... 

Commercial spun bonded or flash spun products have been made primarily from PE plexifilamentary film-fibril strands and have typically been produced using trichlorofluoromethane as a spin agent. 

Disposable cartridge filters should be made of synthetic, non-degradable materials such as nylon or polypropylene. Their construction can be spun-bonded or melt-blown, string-wound, and pleated. These are described below. 

Includes olefin film, olefin fiber, and spun-bonded polypropylene. 

Polystyrene is heavier than the spun-bonded covers and is popular with nursery owners for protecting perennial plants from the extremes of winter. 

As a means of incorporating the fiber sensors into systems, incorporation of in-line fiber sensors into non-woven fabrics was explored. In order to incorporate an in-line sensor into a textile fabric, a spun-bonded base fabric was taken and an in-line fiber sensor was placed on top of it. Subsequently, non-woven fibers of polyurethane were electrospun on top of the optical fiber sensor to hold the sensor fiber in its position, thereby incorporating it in a non-woven fabric matrix. The electro-spinning was carried out at a voltage of 18 KV using a solution of polyurethane in the solvent DMP. 

Recent studies have indicated direct correlations between surface area and catalytic activity of metal oxide sensors (Li et al. 1999). Therefore, it is evident that incorporating catalytic particles by coating techniques may affect surface area and catalysis. Studies by Lee and Bhat (2003) have demonstrated that by incorporating small amounts of electrospun nanoflbers in spun-bond and melt-blown nonwovens, barrier properties such as flitration efficiency and air permeability can be improved. 

Spun-bonded polyethylene (e.g., Tyvek) is used in strong mailing envelopes. How should these be marked so that they would not end up in the recycling of paper, where they cause complications ... 

The smaller the fiber diameter used in the prefilter, the greater the surface area for adsorption of particles and the better the retention of small particles. In the sixties, asbestos fibers were recognized as the best prefilter media. The individual fibrils were smaller than 0.01 ju and they had a positive zeta potential. However, when it was suspected that asbestos fibers presented a health hazard, fine diameter glass and synthetic polymer fibers were substituted. Unfortunately, neither media equals the performance of asbestos. Glass fibers are available in the finest diameters, but some users are fearful they may represent a similar health hazard. The trend has been to use polypropylene or polyester fiber prefilters. Melt blown or spun-bonded fibers are available in diameters near 1 ju. Multilayers of these media with appropriate calendering have resulted in surprisingly efficient prefilters. 

Additional strength is sometimes provided by casting the membrane on a spun-bonded polyethylene or polypropylene backing (see Figure 3.2). 

Figure 3.2 Cross-section of UF membrane cast on spun-bonded polyethylene backing.

Why is radiant sealing, rather than bar or impulse sealing, used for spun-bonded polyolefin ... 

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