Reactive Blends of Thermoplastic Starch and Epoxidized Natural Rubber with Chlorhexidine Gluconate Compatibilizer and Antimicrobial Agent

Abstract

In this study, reactive blending of thermoplastic starch (TPS), chlorhexidine gluconate (CHG), and epoxidized natural rubber (ENR) was performed. CHG was incorporated to improve compatibility via crosslinking and antimicrobial properties, whereas ENR was added to improve the flexibility and interfacial compatibility of the TPS/CHG/ENR blends. TPS was prepared from gelatinized cassava starch and glycerol (70/30 wt/wt%) at 70 °C. CHG was incorporated into TPS at concentrations of 0.5, 1, 2, 5, and 10% (w/w). The TPS/CHG (0.5–10%) samples were melt-blended with ENR (90/10 wt/wt%) at 135 °C. FTIR confirmed the hydrogen bonding of TPS/CHG, whereas the opening of the epoxy ring formed a C–O–C reaction with the –NH2 groups of CHG. In the TPS/CHG5/ENR blend, the tensile strength increased to 13.8 MPa from the crosslinking reaction. The water contact angle increased from 30° (TPS) to 76° (TPS/CHG10/ENR) after 10 min due to the hydrophobicity of the materials and the crosslinking reaction. The TPS/CHG2/ENR sample exhibited inhibition zones against both Staphylococcus aureus and Escherichia coli, whereas the TPS/CHG10/ENR sample exhibited antifungal activity against Rhizopus oligosporus.