Review on recent advances in cellulose nanofibril based hybrid aerogels: Synthesis, properties and their applications.

With the depletion of fossil fuels and growing environmental concerns, the modernized era of technology is in desperate need of sustainable and eco-friendly materials. The industrial sector surely has enough resources to produce cost-effective, renewable, reusable, and sustainable raw materials. The family of very porous solid materials known as aerogels has a variety of exceptional qualities, such as high porosity, high specific surface area, ultralow density, and superior thermal, acoustic, and dielectric properties. As a result, aerogels have the potential to be used for many different purposes, such as absorbents, supercapacitors, energy storage, and catalytic supports. Recently, cellulose nanofibril (CNF) aerogels have attracted remarkable attention for their large-scale utilization because of their high absorption capacity, low density, biodegradability, large surface area, high porosity, and biocompatibility. Recent advancements have confirmed that CNF-based hybrid aerogels can be proposed as the most privileged and promising novel material in various applications. This comprehensive review highlights the recent reports of the CNF-based hybrid aerogels, including their properties and frequent preparation approaches, in addition to their new applications in the areas of fire retardant, water and oil separation, supercapacitors, environmental, and CO2 capture. It is also assumed that this article will promote additional investigation and establish innovative capabilities to enhance novel CNF-based hybrid aerogels with new and exciting applications.

Study on the Migration Behaviors of Magnesium Oxysulfate Nano-Whiskers in Polypropylene Composites with Surface Modification.

In this study, surface modification aimed to enhance the compatibility between a hydrophilic inorganic filler and polypropylene (PP) matrix using hydrophobic treatment. Lauric acid, butyl acrylate, and maleic anhydride were employed to modify the filler surface. After treatment, inorganic filler/PP composites were produced using melt-mixing and extrusion-injection molding processes. The study focused on investigating compatibility and migration behavior between the filler and matrix. The findings indicated that hydrophobic modification, specifically with butyl acrylate and maleic anhydride, improved migration issues in nano-whisker, while maintaining favorable mechanical properties even under accelerated thermal aging. However, excessive hydrophobicity induced by superhydrophobic treatment using lauric acid led to reduced compatibility with the matrix, compromising its effectiveness. Consequently, the study revealed the potential of surface modification to enhance interfacial properties and mitigate migration concerns in PP composites for automotive applications.

Recent advances in the development of MXenes/cellulose based composites: A review.

Over the past few years, transition metal carbides, nitrides, and carbonitrides, commonly referred to as MXenes have been discovered and utilized quickly in a range of technical fields due to their distinctive and controlled characteristics. MXenes are a new class of two-dimensional (2D) materials that have found extensive use in a variety of fields, including energy storage, catalysis, sensing, biology, and other scientific disciplines. This is because of their exceptional mechanical and structural characteristics, metal electrical conductivity, and other outstanding physical and chemical properties. In this contribution, we review recent cellulose research advances and show that MXene hybrids are effective composites that benefit from cellulose superior water dispersibility and the electrostatic attraction between cellulose and MXene to prevent MXene accumulation and improve the composite's mechanical properties. Electrical, materials, chemical, mechanical, environmental, and biomedical engineering are all fields in which cellulose/MXene composites are used. These properties and applications-based reviews on MXene/cellulose composite, critically analyze the results and accomplishments in these fields and provide context for potential future research initiatives. It examines newly reported applications for cellulose nanocomposites assisted by MXene. To support their development and future applications, perspectives and difficulties are suggested in the conclusion.

Tailoring Mesopores and Nitrogen Groups of Carbon Nanofibers for Polysulfide Entrapment in Lithium-Sulfur Batteries.

In the current work, we combined different physical and chemical modifications of carbon nanofibers through the creation of micro-, meso-, and macro-pores as well as the incorporation of nitrogen groups in cyclic polyacrylonitrile (CPAN) using gas-assisted electrospinning and air-controlled electrospray processes. We incorporated them into electrode and interlayer in Li-Sulfur batteries. First, we controlled pore size and distributions in mesoporous carbon fibers (mpCNF) via adding polymethyl methacrylate as a sacrificial polymer to the polyacrylonitrile carbon precursor, followed by varying activation conditions. Secondly, nitrogen groups were introduced via cyclization of PAN on mesoporous carbon nanofibers (mpCPAN). We compared the synergistic effects of all these features in cathode substrate and interlayer on the performance Li-Sulfur batteries and used various characterization tools to understand them. Our results revealed that coating CPAN on both mesoporous carbon cathode and interlayer greatly enhanced the rate capability and capacity retention, leading to the capacity of 1000 mAh/g at 2 C and 1200 mAh/g at 0.5 C with the capability retention of 88% after 100 cycles. The presence of nitrogen groups and mesopores in both cathodes and interlayers resulted in more effective polysulfide confinement and also show more promise for higher loading systems.

Migration Behavior of Lubricants in Polypropylene Composites under Accelerated Thermal Aging.

The surface migration of lubricants degrades the quality of thermoplastic polymer composites. In this study, the surface migration of lubricants in polypropylene composites were studied to improve the quality of the composites. Polypropylene (PP)/lubricant composites were manufactured using a co-rotating twin-screw extruder and injection molding, and the migration phenomena of the lubricant in the PP/lubricant composites were investigated under accelerated aging conditions with temperatures in the range of 20 to 90 °C and humidity of 100% for 72 h. The interrelation between the surface migration properties of PP/lubricant composites were investigated by considering their microstructural and morphological features, which were influenced by the thermal aging conditions. Further, the microstructural and morphological features were examined by contact angle, surface energy, attenuated total reflectance Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy, close-up digital imaging, and atomic force microscopy analyses. The polypropylene composites containing the magnesium stearate as the lubricant were found to exhibit a more stable migration behavior than the polypropylene composites containing a calcium stearate lubricant. This is attributed to multiple synergistic factors, such as interfacial tension and work of adhesion between PP and the lubricant. The findings of this study can be utilized to effectively manufacture high-quality thermoplastic composites for the fourth industrial revolution.

Fabrication of Carbon Fiber Reinforced Aromatic Polyamide Composites and Their Thermal Conductivities with a h-BN Filler.

In this study, a carbon fiber-reinforced thermoplastic composite was fabricated using a new aromatic polyamide (APA) as a matrix. Non-isothermal crystallization behaviors in the cooling process of APA resin (a semi-crystalline polymer) and composite were analyzed by using a differential scanning calorimeter (DSC). To determine the optimum molding conditions, processing parameters such as the molding temperature and time were varied during compression molding of the Carbon/APA composite. The tensile and flexural properties and morphologies of the fabricated composites were analyzed. Molding at 270 °C and 50 MPa for 5 min. showed relatively good mechanical properties and morphologies; thus, this condition was selected as the optimal molding condition. In addition, to enhance the thermal conductivity of the Carbon/APA composite, a study was conducted to add hexagonal boron nitride (h-BN) as a filler. The surface of h-BN was oxidized to increase its miscibility in the resin, which resulted in better dispersity in the APA matrix. In conclusion, a Carbon/APA (h-BN) composite manufactured under optimal molding conditions with an APA resin containing surface-treated h-BN showed a thermal conductivity more than twice that of the case without h-BN.

Fabrication of Activated Carbon Fibers with Sheath-Core, Hollow, or Porous Structures via Conjugated Melt Spinning of Polyethylene Precursor.

Using polyethylene as carbon precursor, we have fabricated cost-effective carbon fibers with a sheath-core structure via conjugate melt spinning. Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) were used as the sheath and core of the fiber, respectively, while sulfonation with sulfuric acid was conducted to enable the crosslinking of polyethylene. We demonstrated that carbonization and activation of the sheath-core-structured polyethylene fiber can result in a well-developed microporous structure in the sheath layer, and due to the core-sheath structure, the resulting activated carbon fibers exhibit a high tensile strength of ~455 MPa, initial modulus of ~14.4 GPa, and Brunauer-Emmett-Teller (BET) surface area of ~1224 m2/g. Finally, activated carbon fibers with a hollow, sheath-core, and porous were successfully fabricated by controlling the degree of crosslinking of the LDPE/HDPE sheath-core fiber.

Fabrication of Piezoelectric PVDF/PAR Composites Using a Sheath-Core Fiber Method.

We report the preparation of sheath-core type fibers made from poly(vinylidene fluoride) (PVDF) and polyarylate (PAR) using melt conjugate spinning to fabricate piezolectric composites. The morphology of this sheath-core fiber was determined through scanning electron microscopy. Subsequently, by the compression molding of the PVDF/PAR sheath-core fiber assembly, we fabricated PVDF/PAR composites exhibiting piezoelectric properties. For enhancing the piezoelectric properties, we increased the concentration of PVDF ß-crystalline phase in the PVDF/PAR composite through poling post-treatments. The resulting crystal structure of PVDF was confirmed through infrared spectroscopy and X-ray diffraction. A universal testing machine was employed to measure the tensile properties of the PVDF/PAR composites. Finally, through a hydrothermal growing method, ZnO was coated on the composite surface to enhance the piezoelectric properties, which were subsequently optimized by varying the hydrothermal growing conditions.

Preparation of PVDF/PAR Composites with Piezoelectric Properties by Post-Treatment.

Thermoplastic composites were prepared using poly (vinylidene fluoride) (PVDF) as the matrix with piezoelectric properties and aromatic polyarylate (PAR) as the reinforcing component. The PVDF/PAR conjugate fibers were prepared by melt conjugate spinning. The PVDF/PAR composites were prepared by compression molding of the PVDF/PAR conjugate fiber laminates at various molding temperatures. Drawing and poling post-treatments of the PVDF/PAR composites were performed to increase the ß crystalline phase content of the PVDF. The morphologies of the PVDF/PAR composites were observed by scanning electron microscopy, and the tensile properties were tested using an universal testing machine. The crystal structure of the PVDF/PAR composites was confirmed by Fourier transform infrared spectroscopy and X-ray diffraction. The piezoelectric properties were tested using voltmeters and multimeters. The post-treatments enhanced the content of the ß crystalline phase of the PVDF matrix, thereby improving the piezoelectric properties of the composites. A molding temperature of 180 °C, drawing temperature of 90 °C, and poling voltage of 12 kV were identified as the optimal conditions for the preparation of the PVDF/PAR composite.