Effects of citric acid and polyamide-epichlorohydrin composite modification on the mechanical, hydrophobic, and thermal properties of starch/plant fiber foaming tableware materials

The environmental pollution and health hazards associated with petroleum-based plastic foams are increasingly becoming evident. The foam produced from natural polymers such as starch and plant fibers, which possess biodegradable properties, holds promise as a substitute for plastic products. Therefore, this study prepared a starch/plant fiber foam tableware material made of thermoplastic cassava starch and plant fiber using the hot-pressing method, and used citric acid (CA) and polyamide-epichlorohydrin (PAE) for binary compound hydrophobic modification. PAE is positively charged and CA is negatively charged. When they are modified in different proportions, the charge between materials can be offset and the esterification reaction process of each other can be jointly promoted, so that the performance of foaming materials can be further improved. When the CA/PAE ratio is 2/3, the foam exhibits superior hydrophobic properties, with a water contact angle of 124.1 degrees C and a maximum water absorption rate of merely 198.6 %. Additionally, the mechanical properties of the material are enhanced, with the flexural modulus reaching 813.31 MPa. Concurrently, both the viscoelastic properties and thermal stability of the foam are improved.