Research and development of nanocellulose and nanocellulose-reinforced composite materials have garnered substantial interest in recent years. This is greatly attributed to its unique functionalities and properties, such as being renewable, sustainable, possessing high mechanical strengths, having low weight and cost. This review aims to highlight recent developments in incorporating nanocellulose into rubber matrices as a reinforcing filler material. It encompasses an introduction to natural and synthetic rubbers as a commodity at large and conventional fillers used today in rubber processing, such as carbon black and silica. Subsequently, different types of nanocellulose would be addressed, including its common sources, dimensions, and mechanical properties, followed by recent isolation techniques of nanocellulose from its resource and application in rubber reinforcement. The review also gathers recent studies and qualitative findings on the incorporation of a myriad of nanocellulose variants into various types of rubber matrices with the main goal of enhancing its mechanical integrity and potentially phasing out conventional rubber fillers. The mechanism of reinforcement and mechanical behaviors of these nanocomposites are highlighted. This article concludes with potential industrial applications of nanocellulose-reinforced rubber composites and the way forward with this technology.

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Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8–10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites.

Rubber gloves used for protection against chemicals or hazards are generally prone to tearing or leaking after repeated use, exposing the worker to potentially hazardous agents. Self-healing technology promises increased product durability and shelf life appears to be a feasible solution to address these issues. Herein, we aimed to fabricate a novel epoxidized natural rubber-based self-healable glove (SH glove) and investigate its suitability for handling pesticides safely. In this study, breakthrough time analysis and surface morphological observation were performed to determine the SH glove’s ability to withstand dangerous chemicals. The chemical resistance performance of the fabricated SH glove was compared against four different types of commercial gloves at different temperatures. Using malathion as a model pesticide, the results showed that the SH glove presented chemical resistance ability comparable to those gloves made with nitrile and NR latex at room temperature and 37 °C. The self-healing test revealed that the SH glove could be self-healed and retained its chemical resistance ability close to its pre-cut value. Our findings suggested that the developed SH glove with proven chemical resistance capability could be a new suitable safety glove for effectively handling pesticides and reducing glove waste generation.

This study investigated the emulsifying properties of a protein–polysaccharide hybrid nanoconjugate system comprising cellulose nanocrystals (CNC, 1% w/v) and soy protein isolate at various concentrations (SPI, 1–3% w/v). The average particle size of the nanoconjugate increased, and the zeta potential decreased when 3% (w/v) of SPI was used. The contact angle and thermal stability of CNC improved with the conjugation of SPI. Upon Pickering emulsification, 0.5% (w/v) of CNC–SPI nanoconjugate as particle stabilizer was sufficient to obtain stable emulsions. The CNC–SPI1 formulation (CNC to SPI, 1:1) provided the emulsion with the smallest droplet size and higher emulsifying activity. Intriguingly, ultrasound (US) pre-treatment on nanoconjugates before emulsification significantly reduced the size of the emulsion. The rheological assessment demonstrated that the CNC–SPI-stabilized emulsions exhibit shear thinning behavior at a lower shear rate and shear thickening behavior at a higher shear rate, indicating the interruption of existing attractive interactions between the CNC particles. All emulsions exhibited higher elastic modulus (G′) than viscous modulus (G″), suggesting high viscoelastic properties of the emulsions. This study demonstrates that CNC–SPI nanoconjugate with optimum protein to polysaccharide ratio has great potential as a natural particle stabilizer in food and nutraceutical emulsion applications.

In this study, ultrasonically driven biosynthesis of zinc oxide nanoparticles (ZnO NPs) using Swietenia macrophylla seed ethyl acetate fraction (SMEAF) has been reported. X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the presence of a pure hexagonal wurtzite structure of ZnO. Field emission scanning electron microscope images revealed the formation of uniquely identifiable uniform rice-shaped biologically synthesized ZnOSMEAF particles. The particle sizes of the biosynthesized NPs ranged from 262 to 311 nm. The underlying mechanisms for the biosynthesis of ZnOSMEAF under ultrasound have been proposed based on FTIR and XRD results. The anticancer activity of the as-prepared ZnOSMEAF was investigated against HCT-116 human colon cancer cell lines via methyl thiazolyl tetrazolium assay. ZnOSMEAF exhibited significant anticancer activity against colon cancer cells with higher potency than ZnO particles prepared using the chemical method and SMEAF alone. Exposure of HCT-116 colon cancer cells to ZnOSMEAF promoted a remarkable reduction in cell viability in all the tested concentrations. This study suggests that green sonochemically induced ZnO NPs using medicinal plant extract could be a potential anticancer agent for biomedical applications.

The development of functional antimicrobial metal oxide nanocomposite systems based on nanocellulose has been the subject of extensive research in recent years. In addition to its sustainability, biodegradability and non-toxic properties, nanocelullose present an extremely high surface area favoring the selective growth and immobilization of ultrafine metal oxide nanoparticles on the cellulosic surface. In this study, oil palm biomass-derived cellulose nanofiber (CNF) decorated with zinc oxide (ZnO) nanocomposites were produced via ultrasound-assisted in situ co-precipitation approach. The morphology and chemical composition of the as-synthesized ZnO/CNF composites were characterized using field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared (FT-IR). FE-SEM images revealed the fibrous morphology of nanocomposites with a good distribution of ZnO NPs. The FT-IR analysis confirmed a strong interaction between surface functional groups of CNF and ZnO nanoparticles. The swelling behavior of composites was found to be improved with addition of ZnO nanoparticles in the CNF matrix. The hybrid ZnO-CNF exhibited pronounced antibacterial properties against methicillin-resistant Staphylococcus aureus (MRSA). The findings of present study support the possibility of using this palm CNF-based metallic nanocomposites as nanofillers for wound care application.