Fabrication of optically transparent and strong nanopaper from cellulose nanofibril based on corncob residues

In this study, a strong and optically transparent nanopaper was fabricated from cellulose nanofibril (CNF) of corncob residues, an abundant byproduct from the processing of corncobs. Two processes were applied to successfully generate CNF from corncob residues. The resultant CNF mainly consists of fibers with diameter (height) of about 1.0 - 5.0 nm on average. The results showed that the as-prepared cellulose nanopaper (CNP) exhibited good strength, optical and thermal properties, with the tensile strength and tensile fracture strain of CNP being 65.3 MPa and 2.3%, respectively; the optical transmittance was close to 90% in the visible range; the highest degradation peak temperature was about 290 °C; the water contact angle at 30 s was 68.2°; A-CNP showed much higher optical properties and hydrophobicity, similar thermal ability, but slightly lower strength properties, compared with B-CNP. It can be seen that corncob residues are suitable choice of raw material for cellulose nanopaper, and is expected to find similar applications in flexible electronics and energy products as those of other raw materials used for this purpose.