2D nanomaterials are finding numerous applications in next-generation electronics, consumer goods, energy generation and storage, and healthcare. The rapid rise of utility and applications for 2D nanomaterials necessitates developing means for their mass production. This study details a new compressible flow exfoliation method for producing 2D nanomaterials using a multiphase flow of 2D layered materials suspended in a high-pressure gas undergoing expansion. The expanded gassolid mixture is sprayed in a suitable solvent, where a significant portion (up to 10% yield) of the initial hexagonal boron nitride material is found to be exfoliated with a mean thickness of 4.2 nm. The exfoliation is attributed to the high shear rates ((Formula presented.) > 105 s−1) generated by supersonic flow of compressible gases inside narrow orifices and converging-diverging channels. This method has significant advantages over current 2D material exfoliation methods, such as chemical intercalation and exfoliation, as well as liquid phase shear exfoliation, with the most obvious benefit being the fast, continuous nature of the process. Other advantages include environmentally friendly processing, reduced occurrence of defects, and the versatility to be applied to any 2D layered material using any gaseous medium. Scaling this process to industrial production has a strong possibility of reducing the cost of creating 2D nanomaterials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

High-Throughput Continuous Production of Shear-Exfoliated 2D Layered Materials using Compressible Flows

Carbon fibers (CFs) have high specific tensile strength, high modulus, and outstanding wear resistance, and are widely used for the reinforcement of advanced composite materials. CF-reinforced thermoplastic composites have received much attention because of their easy processability and recycling convenience compared with thermosetting composites. Surface treatment of CFs is generally employed to increase the surface functional groups and interfacial adhesion between the CFs and the surrounding polymer matrix. In this review, we explore recent advances in the surface treatment of CFs and preparation of CF/thermoplastic composites. The thermal, mechanical, and electrical properties of the composites are also discussed.

Recent advances in carbon-fiber-reinforced thermoplastic composites: A review

Recent advances in fiber/matrix interphase engineering for polymer composites

Researchers have recently focused on the advancement of new materials from biorenewable and sustainable sources because of great concerns about the environment, waste accumulation and destruction, and the inevitable depletion of fossil resources. Biorenewable materials have been extensively used as a matrix or reinforcement in many applications. In the development of innovative methods and materials, composites offer important advantages because of their excellent properties such as ease of fabrication, higher mechanical properties, high thermal stability, and many more. Especially, nanocomposites (obtained by using biorenewable sources) have significant advantages when compared to conventional composites. Nanocomposites have been utilized in many applications including food, biomedical, electroanalysis, energy storage, wastewater treatment, automotive, etc. This comprehensive review provides chemistry, structures, advanced applications, and recent developments about nanocomposites obtained from biorenewable sources.

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Chemistry, Structures, and Advanced Applications of Nanocomposites from Biorenewable Resources.

Graphene and its derivatives are heralded as ‘miracle’ materials with manifold applications in different sectors of society from electronics to energy storage to medicine. The increasing exploitation of graphene-based materials (GBMs) necessitates a comprehensive evaluation of the potential impact of these materials on human health and the environment. Here we discuss synthesis and characterization of GBMs as well as human and environmental hazard assessment of GBMs using in vitro and in vivo model systems with the aim to understand the properties that underlie the biological effects of these materials; not all GBMs are alike, and it is essential that we disentangle the structure-activity relationships for this class of materials.

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Safety assessment of graphene-based materials: focus on human health and the environment

Improvement on fire retardancy of wood flour/polypropylene composites using various fire retardants

The mechanical properties of green-composites based on polylactic acid (PLA) with jute fibers were investigated. A long fiber pellet was developed to obtain a high aspect ratio of residual fiber after injection molding. Comparative studies were carried out, where shorter fiber pellets were compounded by different screw configurations using a twin-screw extruder. To interpret the results of our mechanical tests, the fiber geometry, dispersion state, and fiber fracture surfaces after tensile testing were analyzed. We found that the composites made of short fiber pellet (which suffer high compound intensity), exhibited optimal mechanical performance. Although, compounding with a twin-screw extruder decreased the overall aspect ratio of residual fibers, we observed that it significantly facilitated both the dispersion of the jute yarn to jute bundle and the decohesion of jute bundle to elementary fibers. This fiber separation caused by high intensity mixing led to efficient load transfer from matrix to fiber, and improvement of interfacial strength. These findings provide us with an insight into the critical parameters required to develop a high performing jute/PLA composite.

Strength improvement in injection-molded jute-fiber-reinforced polylactide green-composites

Mass production of high-aspect-ratio few-layer-graphene by high-speed laminar flow

Short-carbon-fiber/polypropylene composites (CF/PP composites) have high processability and recyclability but low strength. To improve the strength, various nanofillers were hybridized to form fiber-reinforced composites. Adding nanofillers improves not only the strength but also the elastic modulus, with the exception of clay nanofillers. To understand the strengthening mechanism resulting from the addition of nanofillers, the residual fiber length and interfacial shear strength were measured. For CF/PP composites, the addition of alumina, silica, and CNT improves the interfacial shear strength, and thereby, the mechanical properties. On the basis of this result, proper choice of nanofiller type and content for improving the mechanical properties of PP/CF composites is discussed.

Yoshihiko Arao

Papers

Improvement on fire retardancy of wood flour/polypropylene composites using various fire retardants

Strength improvement in injection-molded jute-fiber-reinforced polylactide green-composites

Mass production of high-aspect-ratio few-layer-graphene by high-speed laminar flow

Mechanical properties of injection-molded carbon fiber/polypropylene composites hybridized with nanofillers

Efficient solvent systems for improving production of few-layer graphene in liquid phase exfoliation