Effects of Feed Compositions and Screw Configurations on the Properties of Biodegradable Loose-Fill Extruded Foams

In this study, the main effort was to determine the effects of the extruder's operating conditions on the physical, mechanical and chemical properties of corn/PVA extrudates. The operating conditions were feed compositions (FC; food grade corn grit, feeding grade corn grit), screw threads (ST; single, double), screw pitches (SP; narrow (3.5 mm), intermediate (5.0 mm), wide (6.5 mm)), and screw speeds (SS; 50 rpm, 60 rpm, 70 rpm). The experiment was a 2×2×3×3 factorial design. Samples of each treatment were collected and the physical, mechanical and chemical properties were measured and analyzed using the PROC ANOVA and PROC CORR of the SAS 6.0 software package. Experimental results indicated that: screw thread, feed composition, and screw pitch had a most significant effect on the radial expansion ratio and compressibility; whereas, screw speed had a most significant effect on the longitudinal expansion, water absorption index and compressibility, respectively.