Nonwovens mechanical properties

Olefin fibers are used for a variety of purposes from home furnishings to industrial appHcations. These include carpets, upholstery, drapery, rope, geotextiles (qv), and both disposable and nondisposable nonwovens. Fiber mechanical properties, relative chemical inertness, low moisture absorption, and low density contribute to desirable product properties. Table 7 gives a breakdown of olefin fiber consumption by use (73—75). Olefin fiber use in apparel... 

Nonwovens The textile and paper industries are based on the two oldest (wet and dry) processes. Manufacturers of nonwovens for plastics draw on both. With the wet, there are basically two types namely the Fourdrinier and cylinder machine types that have been modified. In addition, two basic types exist for the process formation of the web and application of the bonding agent or system where mechanical carding of fibers is used. The particular equipment and method of operation to be used, with their many modifications, is influenced by desired requirements such as mechanical properties, softness, surface condition, tenacity, etc. There are certain t) es of so-called nonwoven fabric that are directly formed from short or chopped fiber as well as continuous filaments. They are produced by loosely compressing together fibers, yarns, rovings, etc. with or without a scrim cloth carrier assembled by mechanical, chemical, thermal, or solvent methods. Products of this type include melted and spun-bonded fabrics. 

Spinlaying. This process includes various steps, i.e. filament extrusion, drawing, lay down, and bonding. The first two steps can be easily conceived from a typical melt extrusion process. The latter steps involve the deposition of filaments in a random manner on to the conveyor belt. It should be noted that the spunlaid nonwovens are generally self-bonded but additionally they can be bonded by means of thermal, chemical, or mechanical means in order to enhance their mechanical properties. 

Rawal A, Sayeed MMA. Mechanical properties and damage analysis of jute/polypropylene hybrid nonwoven geotextiles. Geotextiles and Geomembranes 2013 37 54-60. 

The multicomponent fibers are substantially biodegradable, yet readily processed into nonwoven structures that exhibit effective fibrous mechanical properties. 

Composite materials are combinations of two or more materials with different, often complementary properties (Cheremisinoff 1997). Polymeric natural fiber composites have traditionally been manufactured using short reinforcement fibers dispersed in a matrix (Van de Velde and Kiekens 2001) or compression molded from a nonwoven textile (Mueller and Krobjilowski 2003). These applications usually contain low fiber volume fractions and lack control of fiber angles, resulting in their primary use as nonload carrying components (Svensson 1997). The role of stiff and strong reinforcing fibers in a composite is to carry the load and improve mechanical properties of the matrix material. Regardless of fiber type (carbon. 

Neat polyester composite showed tensile strength around 41 MPa, Young s modulus around 9.68 GPa, and flexural strength around 61 MPa. After reinforcement with fiber, mechanical properties were enhanced and some of the important properties are explained below. Singh et al. [102] reported that sisal-polyester composites from nonwoven sisal mats with fiber content 50% by volume showed a tensile strength of 30 MPa and a tensile modulus of 1.15 GPa. The composites were manufactured by impregnation of the nonwoven sisal mats under compression molding for 2 hrs [9, 102]. 

Another way of obtaining fibers from agricultural residues is pulping. However, using this method, the obtained fibers are 0.5 to 1.5 mm in length, which is too short to be processed in textiles, nonwoven production and some other industrial applications [7,12]. As known, aspect ratio is a major factor influencing the mechanical properties of a composite. Higher aspect ratio results in better tensile, flexural and impact... 

Hwang Y J, Mccord M G, An J S, Kang B C and Park S W (2005), Effects of helium atmospheric pressure plasma treatment on low-stress mechanical properties of polypropylene nonwoven fabrics , Textile Research Journal, 75,771-778. 

Although the mechanical properties of constituent yams (fibres) are important for balhstic protection, the construction of fabrics can also have a significant effect on balhstic performance. Both nonwoven and woven fabric stmctures of various types with or without resin matrices have been used for ballistic applications. Typical nonwoven fabrics are felts , which are constmcted by randomly orienting and mechanically interlocking the fibres in a form of a web. In contrast, woven fabrics are constmcted through interlacing warp and weft yams. 

After a fiber or yam is produced, it is then fabricated into a textile stmcture in order to obtain the desired form, shape, and mechanical properties for a medical device. There are four alternative types of textile stmctures that are typically used for medical devices. They include wovens, knits, braids, and nonwovens. Each stmcture has its own advantages and disadvantages. For example, woven fabrics are usually stronger and more dimensionally stable and can be fabricated with lower porosities, but are stiffer, less flexible, and more difficult to handle. Knits, on the other hand, have higher permeability and flexibility compared to woven fabrics, but may dilate after implantation. Braids have high longitudinal tensile properties, but can be unstable when subjected to torsional loads. Thus, the type of textile stmcture should be carefully selected when designing the biotextile device, and the medical application and the site of implantation should be taken into account. 

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