SYNTHESIS AND CHARACTERIZATION OF SHAPE MEMORY POLYURETHANE FOR FOOD STORAGE APPLICATIONS

Abstract

The purpose of this study is to examine the impact of film formulations on the development of a packaging film for fresh produce that is more sensitive to changes in temperature and exhibits increased gas permeability. A series of films made from shape-memory polyurethane (SMPU) were produced by casting a mixture of poly (ethylene glycol) (PEG), 1,6-hexamethylene diisocyanate, 1,4-butanediol, and castor oil (CO). The films were evaluated for changes in their thermal, viscoelastic, shape memory properties, and oxygen permeability. The results indicated that the films were uniformly coated without any voids or cracks, and that the SMPU was completely synthesized as evidenced by the absence of the HDI FTIR peak. SMPU produced using 1000 g/mol PEG and 50/50 CO/PEG and 40/60 butanediol/ (PEG + CO) ratios displayed high hydrophobic properties, with a contact angle greater than 95°, and excellent shape-memory properties, with a shape recovery ratio exceeding 90% and a shape fixity ratio exceeding 65%. This film has the potential to be used in the creation of intelligent packaging with greater thermally responsive gas permeability, like the respiration rates observed in fresh produce.