Carboxylated graphene oxide-reinforced polyvinyl alcohol/soy protein composite fibers: thermal and mechanical study

The environmental crisis caused by the use of petroleum-based fibers and the massive depletion of petroleum resources threaten the sustainable development of mankind. Therefore, regenerated protein fibers have gained widespread attention for their green credentials, ingenuity and excellent compatibility. In this work, polyvinyl alcohol (PVA)/soy protein (SP)-carboxylated graphene oxide (GO–COOH) (PVA/SP–GO–COOH) composite fibers were prepared by wet spinning of aqueous solution containing PVA, SP, and GO-COOH. The composite fibers were analyzed for their morphology, structure, thermal stability, and mechanical properties. The results indicated that the composite fibers have both the glossy properties of SP and excellent mechanical properties of PVA. This was attributed to the good dispersion and compatibility of SP and GO–COOH in the PVA matrix. When GO–COOH was added at 0.5% (by weight), the tensile strength of the composite fibers reached 3.29 cN/dtex and the Young’s modulus was 113.92 cN/dtex, which increased by 87% and 67%, respectively, as compared to that of the pure PVA fiber. The moisture regains of the composite fibers reached 8.27%. Furthermore, the maximum decomposition temperature reached 326.7 °C and the thermal stability of the composite fibers increased due to the shielding effect of GO–COOH and formation of hydrogen bonding with the polymer.