Submitted to: Polymers and the Environment
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/2/2010
Publication Date: 2/6/2011
Citation: Shogren, R.L., Selling, G.W., Willett, J.L. 2011. Effect of orientation on the morphology and mechanical properties of PLA/starch composite filaments. Polymers and the Environment. 19(2):329-334. Interpretive Summary: This research found that strong and flexible polylactic acid (PLA)/starch fibers could be made by extrusion followed by stretching and that these have potential use in textiles and disposable packaging. Addition of corn starch to PLA (a corn-based plastic) can lower cost and confer other useful properties. However, addition of corn starch normally causes strength and flexibility of PLA to decline. It has been found that stretching PLA/starch while still hot gives such flexible fibers that these can be bent and tied in knots. Starch also has the potential to make the fibers biodegrade more rapidly and to serve as a carrier for dyes, fragrances or antimicrobials. This information will benefit scientists in academia and industries who are involved in making biobased and compostable materials for packaging, textiles and automotive/appliances.
Technical Abstract: PLA/starch fibers were produced by twin screw extrusion of PLA with granular or gelatinized starch/glycerol followed by drawing through a set of winders with an intermediate oven. At 30% starch, fibers drawn 2-5x were highly flexible (elongation 20-100%) while undrawn filaments were brittle (elongation 2-9%). Tensile strength and moduli increased with increasing draw ratio but decreased with increasing starch content. Mechanical properties were better for composites made with gelatinized starch/glycerol than granular starch. In conclusion, orientation greatly increases the flexibility of PLA/starch composites and this may be useful not only in fibers but also possibly in molded articles. Other advantages of starch addition could include fiber softness without added plasticizer, moisture/odor absorbancy and as a carrier for active compounds.