Green Plasticizers for Biodegradable Mulch Films

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Sustainability currently pervades aspects of many industries and one of the oldest and easiest to embody sustainability principles is agriculture. The industrial partner, FilmOrganic, produces 100% organic compostable mulch film. Applying such a film compared to traditional polyolefin films for beds such as poly(ethylene) (PE) has several advantages. In contrast to PE, farmers do not need to lift the film, remove and then dispose it. Instead, the film gets tilled into the soil at the end of the season, where it decomposes under enzymatic action. Besides this key advantage, the mulch film still prevents weed growth, maintains soil humidity, increases soil temperature and reduces the need for fertilizer and pesticides. Recently, however, the use of mulch films for organic food products has become increasingly more regulated in the USA as of Jan. 2015, where the film must be not only biodegradable and be non-petroleum derived, but also must be derived from non-genetically modified sources (GMO). This restriction is expected to expand to Canada and thus FilmOrganic is considering poly(hydroxyalkanoate) (PHA), which is synthesized by bacterial fermentation. Most common PHAs are poly(3-hydroxybutyrate) (PHB), which are amenable to extrusion, molding etc. but are highly crystalline and therefore quite brittle and thermally degradable at common processing temperatures. Thus, like other biodegradable polymers such as poly(lactide) (PLA), the material often requires blending with other polymers or plasticizers or copolymerization (a copolymer of 3-hydroxybutyrate with 3-hydroxyvalerate (HV) has been used) to provide the mechanical properties needed. Our group at McGill has been involved in collaborative, inter-disciplinary projects to develop a green plasticizer that not only exhibits excellent biodegradability, but is processable and exhibits mechanical properties as good or better than existing phthalate-based plasticizers such as di-2-ethylhexyl phthalate (DEHP). This project's goal is to apply the families of green plasticizers we have developed to plasticize PHA with the goal of making 100% compostable non-GMO films.