Strong Poly(Vinyl Alcohol) (PVA)/Bamboo Charcoal (BC) Nanocomposite Films with Particle Size Effect

In this paper, bamboo charcoals (BCs) were considered as alternative ecofriendly and sustainable carbon-based nanoparticles because of their good affinity with water-soluble biopolymer poly(vinyl alcohol) (PVA) to achieve strong PVA/BC nanocomposites. Two different types of BC particles, namely microdiameter bamboo charcoals (MBCs) and nanodiameter bamboo charcoals (NBCs) were successfully fabricated by the solution casting method. Nanofiller reinforcement effect was investigated from BC particle size and dispersion, morphological structures, and interfacial interactions between BCs and PVA matrices. Overall, the addition of NBCs yields increasingly higher mechanical properties of PVA/BC nanocomposites when compared with that of MBCs. The maximum enhancements in tensile moduli of nanocomposites were achieved up to 123% and 100% with the inclusion of 10 wt % NBCs and MBCs, respectively, whereas corresponding tensile strengths were improved by 110% and 72% with the incorporation of 3 wt % NBCs and MBCs accordingly, as opposed to those of PVA. Such findings obtained may be attributed to more uniform BC particle dispersion in PVA/BC nanocomposites and better interfacial interactions between BCs and PVA matrices. Tensile moduli of PVA/BC nanocomposites were predicted by Halpin Tsai model and combined Mori-Tanaka model and laminate theory in both BC well-aligned and randomly oriented states, suggesting that the introduction of effective volume fractions of randomly oriented BCs led to the best modulus estimation. This study confirms the necessity of using BCs to replace conventional carbon-based nanofillers for developing more economical and eco-friendly nanocomposites.