Microcellular foam processing of biodegradable polymers - review

Polymers are the most widely used materials because of their ease of processing, low cost, and low density. But many of these materials are not easily recyclable and are difficult to degrade completely in nature, creating environmental problems. Considerable researches are underway to make naturally synthesized and biodegradable materials that are easily degraded and less likely to cause environmental pollution. As improved, lower-cost biodegradable polymers become available, we expect that research on foaming processes will be undertaken to further reduce the cost and weight and to improve function, ultimately increasing applicability. In this article, we review the microcellular foaming process as a thermoplastic forming process. We divide the microcellular foaming process into batch, injection, and extrusion processes and review the purpose and result of each. Easier-molding foamed biodegradable polymer will enable the substitution of most current foamed polymer products with products made of foamed biodegradable polymers.