Composite nano-structured calcium silicate phase change materials for thermal buffering in food packaging

Abstract

A new nano-structured calcium silicate (NCS) – phase change composite material has been developed to provide effective thermal buffering for paperboard packages during the transport and temporary storage of chilled perishable food from the supplier to the market. NCS is a proprietary material comprising nano-size platelets stacked together in a unique open framework structure having a high pore volume and liquid absorbency. Alkane phase change materials (PCMs) which absorb and release latent heat energy (∼160–190Jg−1) can be used in heat storage and release applications as they are non-toxic and their operating temperature range can be tuned by the hydrocarbon chain length. The major practical problem of containing the liquid phase has been overcome here by incorporating the alkane PCM (Rubitherm RT6, melting point 8°C) into the highly porous NCS matrix to a level of about 300 wt% of NCS. A paperboard container constructed and lined with six bubble wrap “Post-It” bags containing 400g NCS-300PCM composite provided sufficient thermal buffering capacity to maintain the temperature inside the container at 10°C for some 5h after the outside temperature had increased to about 23°C. A similar performance was obtained when the container was filled with 2kg of asparagus, as a model for perishable food. The NCS-300PCM composite therefore provides sufficient thermal buffering to ensure perishable food in a paperboard container remains below 10°C during transport and temporary storage en route from the supplier to the market.