Poly(Lactic Acid)/Starch Blend for a Degradable Agricultural Mulch Film

Agricultural mulch films are used for the production of vegetables and fruits. Thin plastic films (typically polyethylene) are spread along the rows of plants at the beginning of the growing season. Holes are made in the films to plant the seeds or seedlings. The use of mulch films speeds the ripening of crops, conserves moisture and fertilizer, and inhibits weed growth, fungus infection and insect infestation. At the end of the growing season (generally 3-5 months) the film, contaminated with dirt and vegetation, must be collected, transported and disposed. As the use of mulching films becomes more common, the disposal of the polyethylene film becomes a significant waste problem. The Phase I R&D project determined that a degradable agricultural mulch film from a poly(lactic acid)/starch blend could be produced and mechanical and exterior exposure field tests were conducted. The Phase II research program will focus on moving the polymer blending process to full-scale manufacturing equipment and procedures, optimizing the film manufacturing parameters and conduct large scale product field testing. Film product will be produced on a full-scale manufacturing line and the film tested for initial and aged mechanical properties, soil plot field application and exterior exposure performance. The development of a truly degradable mulching film will reduce labor and disposal costs for agricultural producers. The PLA/starch polymeric blend utilizes 99% biobased materials and its use will displace petroleum derived polyethylene mulch films.