ELECTROSPINNING OF REINFORCED AND FUNCTIONALIZED STARCH FIBERS

The development of bio-based materials from renewable resources to substitute for petroleum-based synthetics has been an area of interest, as well as, a primary research challenge for scientists. Dedicated research in this area will allow for conversion of agricultural commodities to high value-added materials at a very low cost and in a sustainable manner. One such application is nonwoven fibers. Because agriculture-derived biopolymers are generally biodegradable, biocompatible, and hydrophilic, fibers manufactured from them are regarded as suitable substitutes for petroleum-based synthetic polymers in textile, sanitary, and biomedical applications. Among the most attractive agriculture-derived biopolymers is starch. Starch, synthesized by plants via photosynthesis, is one of the most abundant biopolymers in nature and the least expensive on the market. In addition to its sustainable supply and inherent biodegradability, starch has functional advantages over synthetic polymers. Starch is more hydrophilic than synthetic polymers, and thus can be used for improving absorbency. Starch is an ideal material for making biomedical textiles since starch is biocompatible and bioabsorbable. Starch-based sanitary products could provide consumer-related benefits, e.g. easy disposability and flushability. Hence, many attempts to fabricate starch fibers are reported in the research and patent literature. Previous USDA funding resulted in the development of a novel method to produce pure starch fibers by an electro-wet-spinning technique that resulted in fibers with diameters ranging from hundreds of nanometers to tens of microns. Electrospinning employs electrostatic force to deform and elongate polymer melts or dispersions, and has gained much attention in the last decade, because it is currently the only known technique that can fabricate continuous nano-scale ?bers. However, starch fibers in nano-scale (< 100 nm) were not obtained within the experimental range using a simple electrospinning apparatus, and the pure starch fibers were mechanically weak and susceptible to moisture. This challenge has been confronted by many researchers when developing biopolymer-based products. Though some products are commercially available, biopolymer-based materials have not been widely accepted as replacements for their synthetic counterparts. To be competitive in the market, some properties of biopolymer-based materials, for instance, mechanical strength, compliance and moisture sensitivity, will need to be enhanced. For this reason, a new class of composite materials based on biopolymers and nanoclays has generated much attention. Nanoclays consist of two-dimensional nano-sized layers, the distance between which is also in the order of nanometers. Examples are naturally occurring layered mineral silicates, including montmorillonite (MMT), and synthetic layered double hydroxides (LDH). Awareness of the potential of polymer/clay nanocomposites has increased since the late 1980s when Toyota researchers showed that incorporation of as little as 5% nanoclay into nylons greatly increased their modulus and heat distortion temperature. Nanocomposites can drastically improve the mechanical properties, thermal stability, and barrier properties of polymers. In addition, nanoclays offer extra benefits, such as low density, low cost, and recyclability. Research activities involving starch and nanoclays have been conducted by many researchers mostly in thermoplastic starch compositions. This project will extend the advances made in the production of starch-based nano-fibers, with the goal of improving their functional properties through the use of nano-composites and production efficiencies. Biomedical applications of the starch-based nano-fibers will be explored as the most promising initial use.