Thermally buffering polyethylene/halloysite/phase change material nanocomposite packaging films for cold storage of foods

Nanocomposite flexible food packaging films that prolong the time that frozen or chilled food products stay cold are demonstrated. Nanohybrids of phase change materials (PCMs) and halloysite nanotubes (HNTs) were prepared as nanofillers with thermal buffering performance. HNTs were impregnated with polymeric PCMs, PEG400 and PEG600, resulting in a mixture of form-stable HNT/PCM nanohybrids that presented consecutive melting transitions in the temperature range of −22 °C – 22 °C. The incorporation of the mixture of HNT/PEG400 and HNT/PEG600 nanonybrids into polyethylene (PE) matrix by melt compounding resulted in flexible nanocomposite films that have acceptable mechanical properties for use in food packaging applications and presented a broad melting transition from −17 °C to 26 °C with a latent heat of 2.3 J/g. The thawing rate of frozen nanocomposite films at room temperature was less than half of the thawing rate of neat PE films. Furthermore, nanocomposite films delayed the warming of frozen and chilled samples for 18 min and 20 min, respectively, relative to neat PE films. Nanocomposite films composed of PCM impregnated HNTs demonstrated here are the first examples of flexible food packaging films with significant thermal buffering capacity in cold chain temperatures and have a great potential to enhance food quality and food safety in cold-chain storage and transportation.