Comparison of Single/Compound Plasticizer to Prepare Thermoplastic Starch in Starch-Based Packaging Composites

There is a recrystallization problem with natural corn starch, the major raw material of new bio-degradable starch-based composites. To improve the adhesive properties between the starch and the fibers in composites, this paper took formamide, urea, glycerol, and glycol as plasticizers to plasticize corn starch each with the proportions (starch: plasticizer) of 10:2, 10:2.5, 10:3, 10:3.5, and 10:4. Analysis of the FTIR spectra showed that the plasticizers plasticized corn starch through the intermolecular hydrogen bonding. The results from this study showed that the hydrogen bonding between the plasticizer and the starch had the strongest bond and the plasticizing performance was the best when the proportion of starch to plasticizer was 10:3. Study of X-ray diffraction curves showed that the crystallinity of formamide-urea plasticized thermoplastic starch was 1.5 %, lower than that of other plasticizers. The SEM investigation showed that starch plasticization promoted a good 3-D network structure.