| This study addresses how one may use a bicomponent islands-in-the-sea (I/S) fiber technology to produce strong micro- and nanofiber webs and to overcome the shortcomings of the thermal bonding process in obtaining of high strength spunbond fabrics. For this purpose a number of polymers were analyzed and polymer combinations suitable for the production of strong I/S fibers were proposed. Moreover, the relationships between the number of islands, polymer composition, and the fiber and fabrics properties were reported.; To produce ultra small filaments, nylon-6 (N6) and poly (lactic) acid (PLA) were used as the islands and sea polymers, respectively. Micro- and nanofibers were obtained by dissolving PLA polymer from the final spunbond nonwovens. The smallest filament diameter, measuring 360 nm, was obtained after the removal of 75% of PLA from the bicomponent fibers containing 360 islands. Hydroentangling was found to be a viable method of bonding of the I/S structures. Hydroentanged micro- and nanofiber based nonwovens demonstrated high tensile and tear strength, which were insensitive to the N6 fiber size and its mechanical properties. Such insensitivity suggested that bonding efficiency and web uniformity were dominant factors influencing the fabric performance.; For the strength optimization of thermally bonded nonwovens, N6/PE I/S fibers were used. In these fibers, the N6 islands had higher strength, modulus, and molecular orientation and lower strain at break than the PE sea; while the sea component had the lower melting temperature than the island. Thus, thermal bonding caused complete melting of the sea, leaving the islands intact along their entire length. During mechanical testing, weak PE acted as a matrix that held the structure together and transferred the stress to stronger islands via strong interface between the polymers. This resulted in the superior performance of the calendered N6/PE I/S fabric over that of the calendered homocomponent N6 web, in which fibers in the bond spots and their vicinities were damaged during bonding. |
