There has been a steady progress in developing synthetic fibers in the past few years. Bicomponent fibers and nanofibers in a core/shell (C/S) configuration, including two dissimilar materials have presented unusual potential for use in many novel applications. These fibers can be produced using a variety of materials via different techniques i.e., coaxial melt spinning and electrospinning. In this review, we discuss the recent advances in C/S fibers and nanofibers' production. The first part has been assigned to the bicomponent fibers manufacturing technology, while production and applications of C/S nanofibers have been described in the second part.

Providing the greater public with the current coronavirus (SARS-CoV-2) vaccines is time-consuming and research-intensive; intermediately, some essential ways to reduce the transmission include social distancing, personal hygiene, testing, contact tracing, and universal masking. The data suggests that universal masking, especially using multilayer surgical face masks, offers a powerful efficacy for indoor places. These layers have different functions including antiviral/antibacterial, fluid barrier, particulate and bacterial filtration, and fit and comfort. However, universal masking poses a serious environmental threat since billions of them are disposed on a daily basis; the current coronavirus disease (COVID-19) has put such demands and consequences in perspective. This review focuses on surgical face mask structures and classifications, their impact on our environment, some of their desirable functionalities, and the recent developments around their biodegradability. The authors believe that this review provides an insight into the fabrication and deployment of effective surgical face masks, and it discusses the utilization of multifunctional structures along with biodegradable materials to deal with future demands in a more eco-friendly fashion.

There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate‐polymer nanocomposites containing aerogel with extremely low density, large open pores, and high surface area are also an important class of polymer nanocomposites. Thus, this article provides an overview on the effect of aerogel on mechanical and thermal properties of polymer‐based nanocomposites. Moreover, the preparation, history, classification, and characteristics of the aerogel are addressed. Among the polymer‐aerogel nanocomposites, various categories including silica and carbon aerogel‐polymer nanocomposites were discussed in detail. POLYM. COMPOS., 39:3383–3408, 2018. © 2017 Society of Plastics Engineers

Electrospun functionalized polyacrylonitrile grafted glycidyl methacrylate (PAN-g-GMA) nanofibers are incorporated between the plies of a conventional carbon fiber/epoxy composite to improve the composite's mechanical performance. Glycidyl methacrylate (GMA) is successfully grafted onto polyacrylonitrile (PAN) polymer powder via a free radical mechanism. Characterization of the electrospun PAN and PAN-g-GMA nanofibers indicates that the grafting of GMA does not significantly alter the tensile properties of the PAN nanofibers but results in an increase in the diameter of nanofibers. Statistical analysis of the mechanical characterization studies on PAN-carbon/epoxy hybrid composites conclusively shows that the composite reinforced with functionalized PAN nanofibers has greater mechanical properties than that of both the neat PAN nanofiber enriched hybrid composite and control composite (without nanofibers). The improved performance is attributed to the grafted glycidyl groups on PAN, leading to stronger interactions between the nanofibers and the epoxy matrix. PAN-g-GMA nanofiber reinforced composite outperforms their neat PAN counterparts in tensile strength, short beam shear strength, flexural strength, and Izod impact energy absorption by 8%, 9%, 6%, and 8%, respectively. Compared to the control composite, the improvements resulting from the PAN-g-GMA nanofiber incorporation are even more pronounced at 28%, 41%, 32%, and 21% in the corresponding tests, respectively.

In this study, the influence of filler shape and filler content on the physical and mechanical properties of silicon carbide/ epoxy nanocomposites was investigated using silicon carbide nanoparticles and nanowhiskers. Samples containing 0.5, 1, 2 and 4 wt% of b-silicon carbide nanowhiskers and nanoparticles in epoxy resin were prepared using a high-intensity ultrasonic liquid processor and casting technique. Mechanical and physical tests such as tensile, flexural, hardness, and wear along with a morphological investigation by FT-IR, scanning electron microscopy and transition electron microscopy were performed. Results of mechanical tests indicating about 20% and 40% improvement were achieved in nanoparticle (1 wt%) and nanowhisker (2 wt%) reinforced samples, respectively. Also mechanical experiment results have been evaluated with theoretical models. Tribological results show that wear and frictional properties improved about 50% and 30%, respectively, by adding silicon carbide nanoparticles (4 wt%) and nanowhiskers (4 wt%) to epoxy resin. TEM and SEM observations showed that nano-fillers are dispersed in low weight ratio but agglomerated above a critical content.