Submitted to: Polymer Processing Society
Publication Type: Abstract Only
Publication Acceptance Date: January 31, 2006
Publication Date: March 1, 2006
Citation: Onwulata, C.I. 2006. Properties of bioplastics from milk proteins. Polymer Processing Society-Yamagata, JA. Proceedings SPI:1-3
Agricultural materials that can be melted and formed using methods such as extrusion or injection molding, have potential as replacements for some or all of the petroleum-based materials in packaging and plastics. In this study, we evaluated the properties of several blends of extruded agricultural materials and found that the properties of extruded blends in pellet form made from milk protein, casein and whey protein isolates, starch and glycerol (MPB) were most suitable as feed material for injection molding. The physical properties of the extruded MPB were moisture 14 – 18%, peak tensile strength 4.5 mPa, thickness 3.9 mm, elongation at break 45%, and storage modulus 5.0 mPa. The pellets were made under the following conditions: mass flow rates (27 to 102 g/min), solids feed rates (0.43 to 2.85 g/sec), moisture (30 to 75%; extrusion temperature profiles were: 35, 35, 50, 75, 90, 100, 100, 90, 80 C. They were then molded into 215 mL cups with a base of 60 mm and height of 70 mm using injection molding at 110 C under pressure of 8.27 x 105 N/m2. Injection molded MPB cups demonstrated that agricultural materials based on dairy ingredients can be processed directly in equipment used by the plastics industry.