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In this study, high-purity cellulose nanofibrils (CNFs) were environmentally friendly extracted from natural bamboo. Physical, chemical, and mechanical treatments were comprehensively investigated, and then ensembled to effectively and efficiently remove lignin and hemicellulose with low energy from raw bamboo fibers, which combine microwave liquefaction, hydrogen peroxide-acetic acid delignification, alkaline treatment, and along with acid hydrolysis. This was able to allow for the extraction of CNFs. Compositional analysis, Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis were performed to investigate and confirm the successful removal of undesirable lignin and hemicellulose. The resultant cellulose fibers were then subjected to a mechanical treatment to obtain the cellulose nanofibrils. It was found that the obtained CNFs have an average diameter of 13 nm with a cellulose purity of 94.52%. Without any further surface modification, the incorporation of bamboo-based CNFs into natural rubber (NR) exhibits significant improvement in their mechanical properties including modulus (~66.67%), tensile strength (~120.83%), toughness (~139.34%), and elongation at break (~31.41%). Interestingly, there is no compromise between tensile strength and elongation at break for the nanocomposites. DMA results also showed that both storage and loss moduli were dramatically enhanced over those of neat NR in their glassy region, which is typically unusual. This study can show, if optimized for material extraction, the great promise to the potential use of natural materials to develop environmentally friendly composites with multi-functionality in a variety of real-world engineering structural applications. [ABSTRACT FROM AUTHOR]

Mass transfer is a critical bottleneck in the development of proton exchange membrane fuel cells (PEMFCs), especially at high current densities. This study aims to enhance the power density, stability, and durability of the PEMFC by modifying the catalyst layer (CL) with polytetrafluoroethylene (PTFE). The influence of varying PTFE contents in CL was assessed through polarization curves, mass transfer resistance (R mt), and oxygen transfer resistance (OTR) tests. The optimal performance was achieved with MEA4 (with 40 % PTFE), demonstrating a power density of 847 mW/cm2 at 1700 mA/cm2, an 8 % increase compared to MEA0 (without PTFE) at 75 °C. The R mt of MEA4 decreased to 0.1148 Ω cm2, a 55 % reduction from MEA0 (0.2522 Ω cm2). A stability test at 1600 mA/cm for 5 h showed MEA4 maintaining a stable voltage at 0.527 V, while the MEA0 exhibited a linear voltage decrease of 0.04 mV/min with significant fluctuations over time. Accelerated stress testing (AST) is conducted under the DOE standard by 2000 voltage cycles with a triangle sweep voltage from 1.0 V to 1.5 V, which revealed that the OTR of the MEA0 increased by 37 % from 0.7198 s/m to 0.9914 s/m, whereas the MEA4 was observed to be increased from 0.74707 s/m to 0.8253 s/m with a rise of 10.5 %. In conclusion, the incorporation of PTFE into the CL enhances oxygen transfer within the CL, thus improving the power density, stability, and durability of PEMFCs at high current density. [Display omitted] • The addition of PTFE to the catalyst layer facilitates the mass transfer of PEMFC. • The mass transfer resistance of MEA4 is 0.1148 Ω cm2, 50 % lower than that of MEA0. • After AST, the OTR of MEA4 increased by 10.2 %, obviously lower than MEA0's 37.8 %. • The power density, stability, and durability of MEA with 40%PTFE were better. [ABSTRACT FROM AUTHOR]