Phase-change materials for vaccine cold chain applications

When selecting phase-change materials (PCMs), it is important to understand the interactions of the PCMs with the materials with which they may come into contact. PCMs may change the mechanical properties of the material, and a material may impact the phase-change properties (e.g., melting point or latent heat) of the PCM. In this study, we investigated the impact of PCMs on the mechanical and visible properties of materials commonly used in vaccine cold chain equipment (CCE), including refrigerators, cold boxes, and carriers. The materials tested included polypropylene (PP), polyvinyl chloride (PVC), high-density polyethylene (HDPE), high-impact polystyrene (HIPS), copper, aluminum, mild steel,

polyisocyanurate foam, polyurethane foam, enamel appliance paint, and PVC-insulated copper wire. PCMs were classified according to the scheme shown in the figure below. The phase-change materials investigated included water, salt hydrates, paraffins, organic non-paraffins, and a nominal eutectic. Table 1 summarizes the material testing data. We also evaluated the potential hazards to human and environmental health of the PCMs based on information from their safety data sheets (SDS) as well as the useful product life of the PCMs and disposal considerations. Table 2 summarizes the results of the hazards, disposal, and useful product life research.