Evaluating the Use of Predicted Cushion Curves for Comparing the Performance of Some Sustainable Cushion Systems

ABSTRACT This paper studies the cushion performance of a range of sustainable cushion systems and applies two methods to estimate cushion curves from limited cushion test data. The methods employed were previously developed to allow for (1) the conversion of cushion curves representing a material's performance for a given drop height and sample thickness to alternative (non‐measured) drop heights and sample thicknesses and (2) generating a complete cushion curve for a given thickness and drop height from a single acceleration (shock) measurement. The results include those generated for medium‐density polyethylene (MDP) closed‐cell foam for benchmarking of the materials and to aid in validating the approach. The results indicate that predicting cushion curves from single shock measurements is generally accurate for polymeric materials (MDP closed‐sell foam and HDPE inflated bag) but much less so for organic materials (sugarcane bagasse and perforated cardboard). Finally, all alternative cushioning materials and systems evaluated are shown to only be effective for very low static stresses. This finding demonstrates that much higher volumes are required when using the alternative materials to achieve the same cushioning effectiveness as MPD foam. Comparison of cushion curves for all materials investigated clearly shows that the alternative (sustainable) materials are not capable of withstanding static stresses as large as those of MDP closed‐cell foam. Any gain (environmental and economic) achieved by the use of sustainable, readily degradable material will be mitigated by increased volumetric as well as bulk consumption. This points to the need for further work towards the development of processes to enhance the shock absorbing capabilities of such environmentally friendly materials.