One of the major characteristics of nonwovens is that they do not fray. This feature has facilitated the integration of sophisticated laser cut designs within the material, together with the advantages of the sonic bonding process. The FlexAire 541 is one of Tredegar Film Products with exceptional extension and recovery. In addition to this, it has outstanding drape and softness against the skin as compared to the hygiene products for which it is conventionally intended. The fabric has facilitated the production of garments that are modern, striking and totally wearable (Subbiah, Bhat and Tock 557).
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History of the nonwovens
Conventional attire was fundamentally associated with woven and knitted fabrics. These fabrics comprised fibers that were either natural or man-made, or a blend of the two. Production of the fabrics involved intermeshing pre-formed yarns. Such fabric structures have been common in the production of outerwear garments for a very long time, leading to the establishment of garment design and assembly that is primarily dependent on properties and visual appearance. According to Backhouse and Webster, nonwoven fabrics were not popular for outerwear in the past, though the incorporation of nonwoven fabrics into garments and accessories for functional purposes is well-founded especially in protective clothing, garment linings and interlinings, insulation wadding, shoe lining and synthetic leather fabrics, which define both single-use and highly durable products (Backhouse and Webster).
The technical performance and physical properties of the fabrics are essential to their recognition and are therefore readily engineered to meet desired specifications. Such developments in polymers, fabric finishing and nonwoven processing have resulted in noteworthy enhancements in fabric handle and drape, extension and elastic recovery, abrasion resistance and piling, washing stability, dyeing, printing and surface texture that portray the prospect of nonwoven outerwear. In addition to this, the capability of engineering properties that are more complex to attain in traditionally-produced fabrics presents the grounds for exceptional materials that are less expensive alternatives for woven and knitted constructions (Baker 26).
Nonwovens are different to woven and knitted fabrics based on their properties and behavior, which makes the design and assembly of nonwovens more challenging. The border between fashion design and fabric technology is a fundamental requirement for progress in the future. As a result, it is necessary that there be multi-disciplinary research collaboration between designers and fabric technologists (Baker 26).
Developments in nonwoven technology
Nonwoven fabrics are used in everyday life due to the fast development of nonwoven technology. There are new products that spring up every now and then, in addition to the common ones that we are used to like filters, personal care items and automotive products. The recent developments are more focused on nonwovens that have micro-sized fibers. Such nonwoven substrates have the ability to capture particles of varying sizes and chemicals. The surfaces can be used for printing. Nonwovens with micro-sized fibers that are durable can be produced through various technologies including melt blowing and spun bonding. The fabrics with large surface areas comprise exceptionally small fibers measuring about 1 or 2 microns. There has been a significant trend in the industrial and household cleaning markets owed to micro-fiber cleaning products (Bresee, Qureshi and Pelham 11).
The increased surface area leads to value addition that is not confined to wipes. It extends to include military, filtration and medical applications. Popular manufacturing processes for the production of nano and microfibers include electrospinning, spun bonding combined with a fiber-splitting process, and melt blowing. The electrospinning process has the ability to produce filaments with a diameter of 100nm and below. The melt-blowing processes on the other hand can only produce fibers with diameters of over 500nm. The former process has been overwhelmed with problems of low productivity, which limits its commercialization in applications demanding large amounts of fibers. In addition to this, fiber mats produced using this technique require a substrate that will offer the needed mechanical strength (Dutkiewicz ).
The process of melt blowing has drawbacks due owed to the number of polymers that are compatible with the process; moreover, the webs produced via this process are found to be lacking in mechanical strength. Fibers produced using the melt blowing process are weak, which limits their uses and requires extra nonwoven substrate for support (Dutkiewicz 3).
Dutkiewicz (6) tells us of the “microfiber nonwovens use of traditional splittable Bicomponent fibers.” The splittables are defined as fibers in which the two polymers split a general border. In addition to this, the two polymer faces are exposed. The use of microfibers has been rising, from its limited use in suede products, towels and cleaning products. According to Dutkiewicz (6), a “bigger surface area has resulted in the increase of its worth that is not limited to wipes but is instead extendable to include filtration and medical applications. The fabrics with greater surface area improve properties related to drape ability, fluid retention, insulation and durability.” Improved durability is attained by entangling the fabrics (Dutkiewicz 6).
Based on the type of polymers used, curled fibers can result from the side-by-side method. Other popular fibers are the segmented pie and tipped trilobal. The latter is rarely employed as a splittable, though it is applied in the provision of functional polymer on the tips, as a source of suppleness. According to Grotten and Schilling (2004), the “segmented ribbon and segment pie are quite alike, though the end segments are made from the same polymer to bring equilibrium to the structure, and keep it from wrapping.” This in turn causes an odd number of segments. The structures have been proven by Evolon to be durable, flexible, breathable and launderable. In addition to this, they can be dyed or printed in a similar manner to woven fabrics (Fedorova, Verenich and Pourdeyhimi 40).
According to Fedorova, Verenich and Pourdeyhimi (41), “oone of the limitations of the segmented pie structure is that the fibers form wedges and are firmly crammed. The problem comes in when balancing the level of consolidation with tear and tensile strength, or mechanical properties of the fabric.” “Tensile and pilling character is enhanced by advanced consolidation results, though the tear properties are reduced due to limited mobility in the structure, and individual breakages of the fiber when the tear spreads. Tear properties can be improved by lower consolidation, though it leads to reduced resistance to abrasion, pilling and tension” (Fedorova, Verenich and Pourdeyhimi 41).
New generation technologies
This signifies the replacement of splittables with Bicomponent fibers. The latter provides improved flexibility in function and product design. Grafe and Graham tell us that “this is as a result of a common interface between the islands and the sea polymer, whereby the islands are not exposed, unlike the splittables where both polymer phases are exposed in spite of sharing a common interface.” The conventional structure was created and then cleaned with a solvent to get rid of the sea. “Islands-in-the-sea fibers are used in the production of suede and leather fabrics (usually 36 to 48 islands)” (Grafe and Graham 51). This process is observed to be harmful to the environment due to the solvents used in the production process (Grafe and Graham 51).
Studies conducted on the feasibility of I/S cross-sections in the filaments have proven that the arrangement can result in high-strength fabrics. These are attained by using thermal and mechanical techniques to connect the sun bond webs. The mechanical technique used is hydro entangling, while the thermal technique used is calendering. I/S fibers can be fractured or fibrillated. This results in Evolon-like fabrics which have better tear strength. Fracture or fibrillation of the sea phase leads to the sea remaining in the structure, contrary to other examples of Islands-in-the-Sea. This process is more cost-effective and environmentally responsible, as compared to the chemical washing away of the sea. The process for fibrillating the fibers has been observed to be fairly effortless (Grafe and Graham 51).
The process involves causing shear in the fibers by passing them through a calender, before subjecting them to hydro entangling. The full fracture of the fibers’ surface causes the fibrils to dislodge with ease on the surface. This gives the fabric an effect similar to that of suede. The process of calendering involves tying down the fibers, and it regularly enhances the grazing and physical aspects of the fabric. Fracturable structures can also be obtained from the tipped trilobal structure when varying strategies are employed. Fabrics from this process can have stretch and recovery attributes when an elastomer is strategically integrated in the fiber cross section (Groten, Schilling and Bremann).
The durable and launderable nonwovens have multiple applications. It has been observed that Microdenier nonwovens will be a popular material for technical uses in the future, therefore necessitating multi-functional fabrics. A variety of technologies are available, while others are in the process of development at the NCSU Nonwovens institute, which signifies the expected increase in fields and markets for nonwovens that have not been in use before (Groten, Schilling and Bremann).
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This is another nonwoven manufacturing process that produces fibrous articles with filaments whose fiber diameter ranges from 10 to 80 μm. The size of the fiber can however be reduced to 0.3 μm using a Bicomponent spinning process. The Bicomponent extrusion technology uses two polymers to form filaments of varying shape, some of which include sheath and core, segmented-pie, islands-in-the-sea and side-by-side cross-sections. “The Bicomponent fibers are advantageous in that they provide substantial agility in product design and functionalization” (Grafe and Graham 21). The most common Bicomponent fiber configuration at present time is the sheath-core. It is also the most widely used configuration. The other configurations are referred to as splittable fibers, implying that the two polymers split a similar border and both polymer phases are uncovered. The core in the sheath core is however, not exposed. “In the islands in the sea, the islands share a common interface with the sea polymer, though the islands are not exposed” (Grafe and Graham 21).
It is a commercially available nonwoven product. It uses splittable segmented-pie filaments composed of polyester and nylon to obtain a long-lasting nonwoven fabric with micro-fibers. Nowadays, it is produced as a 16 segmented pie spun bond. The fibers are split and bonded mechanically by exposing the web to high pressure hydro entangling. The filaments segments are split into two using a jet. The result is two different filaments, one for polyester and the other one for nylon. The process is suitable for the environment, and is not very expensive. It leads to the formation of a micro-denier structure composed of 2 microns in diameter, assuming round shape for the fibers. The possibility for mechanical splitting is at a minimum due to the weak interface between the two phases of polyester and nylon resulting from their little affinity for each other (Grafe and Graham 21).
The segmented pie structure has a limitation, in that its fibers are wedges, which causes them to crowd firmly. “A 100 gram of fabric has been observed to possess shear strength of 6 to 10 Newtons, and a tensile of about 250 N/5cm” (Li and Xia 1155). This requires the structure to be reinforced with the addition of a scrim for applications demanding higher properties (Li and Xia 1155).
Electro spun fibres
The material comprises fibres that are extremely thin, hundreds of times thinner than human hair. This characteristic makes the material applicable for various uses including protective wear, transportation of drugs and tissue engineering. The technology used to produce such thin strands was discovered and protected as industrial property over one hundred years ago, though it was never used in production till recently. Researchers working on new ways to create electro spun fibres have found ways to integrate materials with fresh aspects like the capability to destroy bacteria, though some applications are unlikely to pay off. One of the laboratories where such investigations are being undertaken is the Rutledge lab, which is one of the pioneers of electro spinning nanofibres. This was after the boom of nanotechnology towards the new millennium. The process of electro spinning has been observed to be routine, though researchers in the Rutledge lab have innovative in creating electro spun membranes with different and beneficial aspects (Pourdeyhimi and Fedorova 3436).
The process of electro spinning leads to the creation of continuous polymer nanofibre. It uses an electrical charge that contains the fibre from a liquid polymer. “A jet of charged fluid polymer sprays out of the bottom of a nozzle, while an electric field forces the stream to lash back and forth, causing the fibre to stretch lengthwise” (Pourdeyhimi and Fedorova 3437). This process causes the diameter to shrink from 100 microns to about 10 nm. The thin membrane is formed from the fibre as it gets in contact with the surface beneath the nozzle. The electro spun membranes have a distinctive blend of strength and ability to stretch. In addition to this, they are easy to handle which makes them appropriate for a broad variety of uses. The membranes contain about 85% open space, making them extremely porous. This property makes them useful as high efficiency particle accumulation, HEPA filters, used in vacuum cleaners and military tanks (Pourdeyhimi and Fedorova 3437).
One of the primary goals for researchers has been the integration of functional materials into the electro spun membranes such as the addition of protective compounds to the polymer to protect against biological and chemical poisonous agents. An example is the addition of chlorhexidine to destroy a majority of bacteria. Another compound is the oximes, which has the ability break down organophosphates. These chemicals are the source of a variety of nerve gases, insecticide and pesticides. Such materials can be used for a variety of purposes including coating of medical devices or creating protective clothing for soldiers. The fibres are also capable of producing breathable, waterproof materials, as seen from the recent creation of an electro spun sheet that is absolutely repellent to water. The material is likely to be more affordable than Gore-Tex, which is made from Teflon, since Teflon is more costly as compared to polymers used in the production of electro spun fibres (Srinivasan and Kathirvelu 34).
Newer developments from researchers in the Rutledge laboratory have indicated the possibility of making breathable electrosun fabrics resistant to both water and oil. “More developments can see electro spun fibres made of block copolymers that self-assemble into a collection of concentric cylinders within the fiber” (Subbiah, Bhat and Tock 557). “These fibers are made by co-axial version of electro spinning technology, and it could be used to impart colour to fabrics without dye, or to create wearable power by combining electrodes into individual fibres” (Subbiah, Bhat and Tock 557).
Tropical treatments for nonwovens
The production of new product using nonwovens is a relatively cheap process, such as the substitution of rayon with polyester or polypropylene nonwoven fabrics. These fabrics have similar performance demands, though the difficulty comes in the substitution of rayon with fabrics that have similar hydrophilic and anti-static properties. These properties are characteristic of polyester and polypropylene fabrics, via the topically applied additives that adjust or improve the surface of the fabric. There are various topically applied treatments including those that provide non-durable or semi-durable hydrophilic properties, hydrophobic properties and antistatic properties (Trafton).
For the applications requiring nonwovens that have hydrophilic properties, they are usually designed for single use applications. These require non-durable hydrophilic finish system that is designed to portray great initial hydrophilic aspects though they are easily washed off to expose the underlying hydrophobic substrate. The treatment has features including great emulsion quality and stability, lower surface tension values, which is good for homogeneous spreading on the fiber surface, and static protection. The finis is applied as spin finish or topcoat finis using kiss roll, spray or dip bath application (Trafton).
There is also a demand for finish chemistries that provide hydrophilic properties through many insults, or are difficult to erase from the surface of the fiber. The semi-durable finishes are designed to have more attracting for the fiber surface, which keeps it from washing off with ease. Finishes maintaining semi-durable hydrophilic features have components with a balanced hydrophile and hydrophobe structure. The increase in performance of semi-durable hydrophilic leads to the decrease in emulsion stability and make application to the substrate more complex (Vasile and Van Langenhove 4).
The challenge posed by markets that demand hydrophobic nonwoven fabric is the provision of lubricity and antistatic protection that is necessary for processing without compromising the hydrophobicity of polypropylene natural to the surface of the fiber. The common hydrophobic topical treatment is silicone, though other options like fluorochemical and low viscosity specialty esters can be used. Most of the nonwoven products, whether hydrophilic or hydrophobic, require static protection. It is necessary to incorporate antimicrobial treatment in nonwoven fabric for consumer and commercial applications nowadays. This is beneficial since it helps to control obnoxious odors, horrid stains and product deterioration (Vasile and Van Langenhove 4).
Backhouse, David and Lynne C. Webster. Fashion: Function in Action. London, UK: University of Leeds International Textiles Archive, 2008.
Baker, Botts. “Bicomponent Fibers.” Int Fiber. Journal (2004): 13, 26. Print.
Bresee, R. R., U. A. Qureshi and M. C. Pelham. “Influence of processing conditions on melt blown web structure.” Int. Nonwovens J. (2005): 14, 11. Print.
Dutkiewicz, Jacek. Nonwoven Structures for Absorption of Body Fluids, monograph. Memphis, TN: Buckeye Technologies, 2004.
Dutkiewicz Jacek. “Some Advances In Nonwoven Structures Forabsorbency, Comfort And Aesthetics.” AUTEX Research Journal (2005): 2(3), 1-7. Print.
Fedorova, N., S. Verenich and B. Pourdeyhimi. “Strength Optimization of Thermally Bonded Spunbond Nonwovens.” JEFF, (2007): 2(1), 38 – 47.
Grafe, T. and K. Graham. “Polymeric Nanofibers and Nanofiber Webs: A New. Class of Nonwovens.” Int. Nonwovens Journal (2004): 12, 51. Print.
Graham, K., M. Gogins and H. Schreuder-Gibson. “Incorporation of Electrospun Nanofibers Into Functional Structures.” Int. Nonwovens Journal (2004): 13, 21. Print.
Groten, Raphaela, et al. “Bonded-fiber Fabric for Producing Clean–room Protective Clothing.” Fractured Bicomponent Nonwovens (2004). Print.
Li, D. and Y. Xia. “Electrospinning of Nanofibers: Reinventing the Wheel?” Advanced Materials (2004): 16 (14), 1151-1170. Print.
Pourdeyhimi, Behnam and N Fedorova. “High Strength Nylon Micro- and Nanofiber based Nonwovens via Spunbonding.” J. Appl. Polym. Sci. (2007): 104 (5), 3434 – 3442. Print.
Srinivasan, J. and S. Kathirvelu. “An Introduction to Spunbond and Meltblown Nonwovens.” Synthetic Fibers (2006): 27 – 36. Print.
Subbiah, T., et al. “Electrospinning of nanofibers.” J Appl Polym Sci (2005): 96(2), 557. Print.
Trafton, Anne. Electrospun fibres for protective clothing, wearable power and more. 2009. Web. 26 April 2011.
Vasile, Simona and Lieva Van Langenhove. “A High Potential Market For. Nonwovens Sound Insulation.” Automotive Industry (2004): 3(4), 1-5. Print.