DEVELOPMENT OF AGRICULTURALLY-DERIVED BIOPOLYMER COMPOSITES FOR NON-FOOD APPLICATION
Location: Bioproduct Chemistry and Engineering Research
Title: Extruded/injection-molded composites containing unripe plantain flour, ethylene vinyl-alcohol and glycerol: Evaluation of color, mechanical property and biodegradability
Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2011
Publication Date: May 5, 2012
Citation: Vargas, A., Berrios, J.D., Chiou, B., Wood, D.F., Glenn, G.M., Bello, L., Imam, S.H. 2012. Extruded/injection-molded composites containing unripe plantain flour, ethylene vinyl-alcohol and glycerol: Evaluation of color, mechanical property and biodegradability. Journal of Applied Polymer Science. 124 (3) pp. 2632-2639.
Interpretive Summary: Surplus commodities put considerable economic pressure on farmers. Finding non-food uses is therefore critical to help farming communities around the world and promote utilization of agriculturally derived renewable polymers. This is the first study that describes the utilization of plantain flour in plastic composites deemed for non-food industrial applications. Plastic composites produced are of excellent mechanical property and retain their ability to biodegrade in natural compost. This represents a breakthrough for plantain producers world-wide and help promote the ARS mission.
Extruded/injection-molded composites were produced from plantain flour blended with ethylene vinyl-alcohol (EVA) and glycerol. Scanning electron microscopy showed composites had a smooth surface and excellent compatibility between plantain flour, EVA and glycerol. The impact of increased plantain flour concentration on films’ color, mechanical property and biodegradation were examined. Impact of storage temperatures (-20oC and 80oC) and relative humidity (RH) conditions on mechanical properties and biodegradation of composite was also examined. An increase in the values of luminosity (L*), chroma (C*) and hue angle (h*) were observed with decreased plantain flour content in the composite. Generally, tensile strength, elongation at break and the displacement all decreased with increased plantain content in the composite accompanied by an increase in elastic modulus. Interestingly, increasing the plantain concentration above 50% had little impact on its mechanical properties. Tensile strength, elastic modulus, elongation at break and displacement in these samples were statistically indifferent (p< 0.05). Mechanical properties of the composites deteriorated quickly when films were pre-exposed at 80 ºC apparently caused by the evaporation of glycerol in formulations at such high temperature. Under increased relative humidity conditions mechanical properties of the samples were quite stable and is attributed to the plasticizer present in the formulation. Composites rapidly biodegraded in a compost environment, however, sample pre-stored at -20oC and 80oC exhibited significantly higher rates and extents of degradation.