Submitted to: Carbohydrate Polymers
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/27/2006
Publication Date: 3/15/2006
Citation: Fishman, M.L., Coffin, D.R., Onwulata, C.I., Willett, J.L. Two-stage extrusion of plasticized pectin/pvoh blends. 2006. Carbohydrate Polymers 65,p.421-429. Interpretive Summary: The need to add value to agricultural residues from fruit juice processing, use surplus corn and the co-products of biofuel production has prompted us develop biodegradable films designed for industrial use. These are fabricated from pectin, starch, poly(vinyl) alcohol and glycerol. Pectin is a by-product of orange juice production and glycerol is a biofuel co-product. In this work we show that pectin/starch/poly (vinyl) alcohol/glycerol films fabricated by extrusion processing could be blown or extruded into biodegradable films that can be used as packaging materials. Commercialization of these films will provide new uses for agricultural byproducts and more revenue for farmers, processors and manufacturers of agricultural materials.
Technical Abstract: Blends of pectin with starch (high amylose and normal), poly(vinyl alcohol) (PVOH), and glycerol were extruded in a twin screw extruder, pelletized, and then further processed into blown film and extruded sheet using a single screw extruder. The samples were analyzed using tensile measurements, dynamic mechanical analysis, and scanning electron microscopy. PVOH levels of 24% or greater were necessary to successfully make blown film, while extruded sheet could be made at a level of 16% PVOH. Tensile strength and initial modulus of the extruded sheets were slightly higher in the machine direction than in the cross direction, while the reverse was true for elongation to break. For the blown films tensile strength tended to be higher in the transverse direction than in the machine direction, while the reverse was seen for initial modulus. Increased levels of PVOH led to increases in tensile strength and elongation to break, while initial modulus was decreased. Morphology as determined by SEM visually indicated stretching in the transverse direction of the blown films. The second stage extrusion appeared to promote a-helix formation in the high amylose starch.