Fabrication of poly(vinyl alcohol) foam/gel composite used for cold storage by combing molding foaming and freeze-thawing technologies

Ice, the widely used low-temperature storage material, plays an important role in the short-time cold chain transportation. To avoid water leakage caused by ice melting, special encapsulation is needed, but inevitably leads to the single shape and the poor contact between ice and the cooled object. It is urgent to develop a new type of leakage-proof cold storage material. Accordingly, in this paper, by combing the technologies of molding foaming and freeze-thawing, a novel cold storage material containing poly(vinyl alcohol) (PVA) carrier foam and PVA gel was fabricated. PVA carrier foam mainly provided the strength foundation, while PVA gel locked the absorbed water. With the addition of 7.0 wt% PVA gel into PVA carrier foam, denser and uniform cells were formed, endowing the foam/gel composite with good shape retention. Even after 500 times’ cyclic compression, the compression curve of the composite still coincided with the original one. The further introduction of 2.0 wt% NaCl into PVA gel enhanced the cold storage effect of the composite, i.e., the temperature in an incubation box could reach −2.5 °C and be maintained for 16 h. This novel PVA foam/gel composite was expected to be used as cold storage material for cold chain transport, and thus broadening the practical application of PVA.