Response surface optimization of the feed compositions of biodegradable packaging foams

Response surface methodology (RSM) was used to analyse the effects of polyvinyl alcohol (PVOH) and calcium carbonate (CaCO 3 ) on the physical and mechanical properties (radial expansion ratio, bulk density, compressibility and spring index) of a biodegradable cushioning extrudate. A rotatable central‐composite design (CCD) was used to develop models for the objective responses. The experiments were run at 125°C with a feed rate of 27.8 l/h, screw speed of 215 r.p.m. and die diameter of 3.92 mm. Responses were most affected by changes in PVOH levels and to a lesser extent by CaCO 3 levels. Individual contour plots of the different responses were overlaid. An optimum radial expansion ratio of 3.39, bulk density of 0.065 (g/cm 3 ), compressibility of 32.27(N), and spring index of 0.906 were identified at 36% PVOH and 5% CaCO 3 . Copyright © 2005 John Wiley & Sons, Ltd.