Unlocking enhanced properties: surface-engineered carbon fibers via microwave-grown ZnO nanoflakes for advanced thermoplastic composites.

Jute stick extract assisted hydrothermal synthesis of zinc oxide nanoflakes and their enhanced photocatalytic and antibacterial efficacy

Superior antibacterial performance of surfactant-assisted ZnO nanoflakes produced via Co-precipitation method

In this present work, an environmentally safe hydrophobic cotton surface comprising of PDMS and different morphology of Zinc oxide (ZnO) nanostructures via simple dip coating method was developed. ZnO nanosphere and ZnO nanoflakes were synthesized via sol gel method while ZnO nanorods were synthesized via solution precipitation method. The precursors used to prepared ZnO nanospheres, nanoflakes and nanorods are zinc acetate dehydrate, zinc chloride and zinc nitrate tetrahydrate respectively. ZnO nanostructures were analysed using FESEM and XRD. The hydrophobic cotton surface was characterized via FT-IR and WCA analysis. A WCA of 144.15° was achieved when coating the cotton with ZnO nanoflakes (ZnO-NF:PDMS).

A novel highly functional plant oil-based polyols, Methoxylated Sucrose Soyate Polyols (MSSP), were cross-linked with isocyanate to formulate MSSP-based polyurethane (PU) thermosets. The degree of cure or conversion was studied using differential scanning calorimetry (DSC). Compression molding process was used to make composite panels out of MSSP-based polyurethane and flax fiber reinforcement of about 50 vol %. The MSSP-based PU resin reinforced with 50 vol % unidirectional E-glass fiber mats was tested as a reference. The composites were cured at 150°C for 60 minutes. Properties of the MSSP-based PU thermosets and its corresponding flax/glass-fiber reinforced thermoset composites were assessed by tensile strength and modulus, flexural strength and modulus, interlaminar shear strength (ILSS), nanoindentation test, and impact strength. Specific tensile modulus and strength of the flax fiber composites were found to compare with those of glass/MSSP-based PU. The glass/MSSP-based PU composite exhibited superior mechanical properties compared to both bio-based and petroleum-based composites used in previous studies. Compared to soybean oil based composites used in previous studies, bio-based composites based on MSSP showed 70 % and 101 % increase in flexural strength and modulus respectively, 102 % and 93 % increase in tensile strength and modulus respectively, and 56 % increase in ILSS. Compared to petroleum-based PU/glass composites used in previous studies, bio-based composites based on MSSP showed 60 % and 40 % increase in flexural strength and modulus respectively, 102 % and 78 % increase in tensile strength and modulus respectively, 50 % increase in ILSS. Higher mechanical properties in MSSP-based PU composites can be attributed to high functionality, rigid and compact chemical structures of MSSP oligomers in polyol resin.

Carbon fiber-reinforced epoxy (CFRE) laminates have attracted significant attention as a structural material specifically in the aerospace industry. In recent times, various strategies have been developed to modify the carbon fiber (CF) surface as the interface between the epoxy matrix and CFs plays a pivotal role in determining the overall performance of CFRE laminates. In the present work, graphene oxide (GO) was used to tag a polyetherimide (PEI, termed BA) containing exchangeable bonds and was employed as a sizing agent to improve the interfacial adhesion between CFs and epoxy. This unique GO-tagged-BA sizing agent termed BAGO significantly enhanced the mechanical properties of CFRE laminates by promoting stronger interactions between CFs and the epoxy matrix. The successful synthesis of BAGO was verified by Fourier-transform infrared spectroscopy. Additionally, the partial reduction of GO owing to this tagging with BA was further confirmed by X-ray diffraction and Raman spectroscopy, and the thermal stability of this unique sizing agent was evaluated using thermogravimetric analysis. The amount of GO in BAGO was optimized as 0.25 wt% of BA termed 0.25-BAGO. The 0.25-BAGO sizing agent resulted in a significant increase in surface roughness, from 15 nm to 140 nm, and surface energy, from 13.2 to 34.7 mN m-1 of CF. The laminates prepared from 0.25-BAGO exhibited a remarkable 40% increase in flexural strength (FS) and a 35% increase in interlaminar shear strength (ILSS) due to interfacial strengthening between epoxy and CFs. In addition, these laminates exhibited a self-healing efficiency of 51% in ILSS due to the presence of dynamic disulfide bonds in BAGO. Interestingly, the laminates with 0.25-BAGO exhibited enhanced Joule heating and enhanced deicing, though the EMI shielding efficiency slightly declined.

We report on label free highly sensitive electrochemical immunosensor for monitoring alcohol consumption through the detection and quantification of ethyl glucuronide (EtG) -a metabolite of ethanol-based on two-dimensional (2D) zinc oxide (ZnO) nanoflakes (NFs), which were synthesized on flexible Au-coated polyethylene terephthalate (PET) substrate using simple one step sonochemical approach. Highly sensitive detection of EtG using cyclic voltammetry (CV) is achieved by immobilizing EtG antibody on the as-synthesized sensing electrodes of ZnO NFs. Continuous monitoring of alcohol detection is imperative for the prevention of accidents, point of care monitoring, and personal safety. The cutting-edge technologies are mostly focused to detect alcohol from the breath (e.g. breathalyzer), which is not compatible for the real-time monitoring. The relationship between the blood and breath alcohol concentrations and the improvement of the detection techniques of alcohol biomarkers from the sweat render an opportunity for point of care monitoring. Among different biomarkers, Ethylglucuronide (EtG) has been found as a promising indicator of alcohol due toit’s prolonged existence in sweat (24 hours for one or two “drinks” or 2-4 days for binge drinking), which prevents relapsing. PET has gained popularity as substrate for wearables because of its intrinsic elasticity, thermal stability, hydrophobicity, excellent dielectric properties, low coefficient of thermal expansion, structural resiliency against repeated bending forces and compatibility with roll-to-roll fabrication processes for low cost and scalable manufacturing. ZnO, a semiconducting material with piezoelectricity,high catalytic efficiency, biocompatibility, chemical stability in physiological environments, low toxicity and a high isoelectric point (IEP) of about 9.5, has been proposed for biosensing applications. ZnO nanostructures (NSs) with different morphologies such as nanorods, nanowalls, nanobelts and quantum dots have been used as immobilizing matrix in fabrication of biosensors for the detection of physiologically relevant biomarkers such as cholesterol, galactose, glucose. Considering their promising properties and potential applications, many techniques have been developed to synthesize various ZnO NSs. In comparison to the more conventional approaches such as hydrothermal method, sonochemical synthesis method is not only significantly faster, inexpensive and performed at ambient conditions but also highly stable and reproducible with the advantages of more uniform size distribution, faster reaction time and a higher surface area, which are essential to design sensing platform withimproved performance. Compared to bulk materials, the 2D ZnO NFs provide unique sensing advantages with polarized (0001) plane orientation and high surface charge density, which could enhance EtG antibody loading and thus improve sensing performance. High isoelectric point allows immobilization of most biomolecules without any additional biding layer. This provides a direct, stable pathway for rapid electron transport when an analyte is immobilized on NFs and improves electron transfer rate greater than 1D ZnO nanorods, high isoelectric point,that results in change of the resistance.Taking advantage of these unique properties, we immobilizedEtG antibody on the synthesized ZnO NFs. When an analyte binds the antibody, there is a change in the current due to increase in the charge transfer resistance. The cyclic voltammetry (CV) measurements were taken in the potential range of -0.1V-0.8V at a scan rate of 50mVs-1. For the EtGconcentrationsof1ng/mL-100µg/mLusing PET/Au/ZnO NFs as the working electrode. The minimum detection limit was found to be much lower than 1ng/mL which covers the physiological range. The sensitivity of the sensor was found to be 18.48 mA/ng/mL/cm-2.

Dodging reality, striking the virtual: An undulating strategy for effectively enhancing CF/PEEK interfacial adhesion!

Nanogenerators have attracted much attention in the past few years due to their high conversion efficiency of mechanical energy into electrical energy that is abundantly available in the environment and everyday human life. Enhancing the electrical output performance of nanogenerator using composite polymeric films (CPFs), i.e., piezoelectric materials embedded in triboelectric polymers, has gained potential interest. The CPFs can provide a high relative permittivity and enhanced surface charge density, resulting in an enhanced electrical output. Herein, piezoelectric zinc oxide (ZnO) nanoflakes (ZnO‐NFs) were synthesized by a hydrothermal reaction process and combined with a nylon polymer to prepare a positive triboelectric composite film. Furthermore, a piezo/triboelectric hybrid nanogenerator (ZnO‐HNG) was fabricated with the prepared nylon/ZnO composite film as a positive triboelectric material and PDMS as a negative triboelectric material, respectively. The effect of the loading concentration of the ZnO‐NFs in the nylon polymer on the electrical output was systematically investigated. The optimized ZnO‐HNG exhibited a stable and enhanced electrical output performance with the voltage, current, charge density, and power density values of ≈300 V, ≈9 µA, ≈85 μC m−2, and ≈4.5 W m−2, respectively. Finally, the ZnO‐HNG was attached to the human body to harvest various mechanical motions involved in everyday human life and power various low‐power portable electronics.

The mechanical properties of carbon fiber (CF) reinforced thermoplastic polymer composites are primarily governed by the interphase between CFs and matrix. However, the inherent inertness of CF surfaces combined with the high viscosity and processing temperatures of thermoplastic resin often result in relatively weak interfacial bonding. This study aims to enhance the interfacial adhesion of carbon fiber reinforced polyamide 6 composites to improve their mechanical properties. CFs were de‐sized and oxidized, followed by re‐sizing with silanized carbon nanotubes. Fracture morphology and composition analysis of the fibers were conducted, and the fibers were subsequently incorporated into composites for mechanical testing. Results revealed a 20.0% increase in tensile strength, a 25.11% increase in flexural strength, and a 24.88% increase in interlaminar shear strength for the resized‐carbon fiber reinforced polyamide 6 composites compared to the pristine‐carbon fiber reinforced polyamide composites. The cross‐sectional morphology of the modified composites exhibited a zig‐zag fracture pattern. Dynamic mechanical analysis indicated that the modified fibers required higher activation energy for the free movement of the polyamide 6 molecular chain. These findings suggest that surface treatment enhances the interfacial adhesive between CF and resin, thereby significantly improving the mechanical properties of carbon fiber reinforced polyamide 6 composites.Highlights An efficient and reliable carbon fiber surface treatment method is proposed. Surface modification improves surface chemical activity of carbon fibers. Composites show substantial improvements in mechanical properties. Interfacial performance enhancement mechanism of composite was revealed.

We investigated a novel catalytic application of nickel-doped zinc oxide (Ni-ZnO) nanoparticles and zinc oxide (ZnO) nanoflakes at room temperature in an aqueous hydrotropic solution for the synthesis of biologically active dihydropyrimidones (DHPMs). Ni-ZnO is a stable, recyclable, green, efficient heterogeneous catalyst which shows maximum yield in a shorter reaction time than ZnO nanoflakes in very mild conditions of hydrotropic aqueous medium for DHPMs syntheses.

Facile fabrication of arecanut palm sheath based robust hydrophobic cellulose nanopapers via self-assembly of ZnO nanoflakes and its shelf-life prediction for sustainable packaging applications

Simultaneous enhancement of mechanical and electrical/thermal properties of carbon fiber/polymer composites via SiC nanowires/graphene hybrid nanofillers

Braided composites possess an advantage of good out-of-plane mechanical properties, near net-shape manufacturing, impact and damage resistance. This work aims to investigate the effect of graphene nanoplatelet (GNP) addition on glass fibre triaxial braided composites (TBC). Tensile, flexural, and short beam shear tests were conducted to investigate the mechanical performance of the pristine and hybrid TBC. A numerical model was framed to estimate the material properties of hybrid TBC which were further used as input for the finite element simulation. Results indicate a 15% increase in tensile strength, a 20% increase in flexural strength and a 10% increase in interlaminar shear strength (ILSS). The experimental results were in good agreement with the analytical results. The braided architecture along with proposed GNP combination further enhances mechanical properties and enables gradual failure of the composite which is a desirable property for load bearing structures.

Mechanical property enhancement of graphene-kenaf-epoxy multiphase composites for automotive applications

Surface modification of carbon fibres with ammonium cerium nitrate for interfacial shear strength enhancement