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United States Department of Agriculture

Agricultural Research Service

Title: Critical Process Parameters for the Twin-Screw Extrusion of Low Density Starch-Based Loose-Fill Foams

item Tatarka, Paul

Submitted to: Annual Meeting of the Bio Environmentally Degradable Polymer Society
Publication Type: Abstract Only
Publication Acceptance Date: September 25, 1996
Publication Date: N/A

Technical Abstract: Starch-based loose-fill currently enjoys approximately 15% of the estimated 100 million lbs per year loose-fill packing foam market. Expanded polystyrene (EPS) loose-fill foam dominates this market because of its low cost and density. Extrusion cooking technologies have been used to produce environmentally benign starch-based loose-fill. To increase market share, starch-based loose-fill foams must have low density without sacrificing performance. Expansion characteristics of starch-based loose-fill are dependent on many twin-screw processing variables, including moisture and amylopectin content, temperature, screw speed, fill factor and die diameter and L/D ratio. Longitudinal expansion is increased by longer die L/D ratio, higher process temperature, and lower amylopectin content. Whereas cross-sectional expansion is increased by lower process moisture, smaller die diameter, and affected by several interactions among temperature, fill- -factor, and screw speed. Volume expansion is a product of cross-sectional expansion and longitudinal expansion. High volume expansion correlated with low foam density. High process temperature of 195 deg C, low process moisture of 16 weight percent, small die diameter of 2.5 mm, and low amylopectin content of 50% significantly increased volume expansion. Many interactions among these process variables were found to affect volume expansion.

Last Modified: 4/22/2015
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