A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

Flame retardant polymeric nanocomposites through the combination of nanomaterials and conventional flame retardants

Cellulose, a well-known fascinating biopolymer, has been considered to be a sustainable feedstock of energy sources and chemical engineering in the future. However, due to its highly ordered structure and strong hydrogen bonding network, cellulose is neither meltable nor soluble in conventional solvents, which limits the extent of its application. Therefore, the search for powerful and eco-friendly solvents for cellulose processing has been a key issue in this field for decades. More recently, certain ionic liquids (ILs) have been found to be able to efficiently dissolve cellulose, providing a new and versatile platform for cellulose processing and functionalization. A series of cellulose-based materials, such as films, fibers, gels and composites, have been produced readily with the aid of ILs. This review article highlights recent advances in the field of dissolution and processing of cellulose with ILs. It is hoped that this review work will stimulate a wide range of research studies and collaborations, leading to significant progress in this area.

Application of ionic liquids for dissolving cellulose and fabricating cellulose-based materials: state of the art and future trends

Photovoltaic (PV) modules are subject to climate-induced degradation that can affect their efficiency, stability, and operating lifetime. Among the weather and environment related mechanisms, the degradation mechanisms of the prominent polymer encapsulant, ethylene-vinyl-acetate copolymer (EVA), and the relationships of the stability of this material to the overall reliability of Si-based PV modules were addressed. The EVA function and properties correlated to its deterioration factors as temperature, moisture, and ultraviolet radiation (UV) were discussed in this work. The main objective of this study is to review the literature on EVA encapsulation and its degradation, which promotes the loss in performance of the PV module. The deleterious effects on EVA such as photodegradation, moisture, delamination, bubble formation and potential induced degradation (PID), their relationship with the polymer structure, chemical, mechanical, optical and electrical properties are approaches carried out in this review. This paper also provides a brief review of the developing field of EVA composites technology aiming at higher performance materials.

The causes and effects of degradation of encapsulant ethylene vinyl acetate copolymer (EVA) in crystalline silicon photovoltaic modules: A review

Piezoelectric materials are widely referred to as "smart" materials because they can transduce mechanical pressure acting on them to electrical signals and vice versa. They are extensively utilized in harvesting mechanical energy from vibrations, human motion, mechanical loads, etc., and converting them into electrical energy for low power devices. Piezoelectric transduction offers high scalability, simple device designs, and high-power densities compared to electro-magnetic/static and triboelectric transducers. This review aims to give a holistic overview of recent developments in piezoelectric nanostructured materials, polymers, polymer nanocomposites, and piezoelectric films for implementation in energy harvesting. The progress in fabrication techniques, morphology, piezoelectric properties, energy harvesting performance, and underpinning fundamental mechanisms for each class of materials, including polymer nanocomposites using conducting, non-conducting, and hybrid fillers are discussed. The emergent application horizon of piezoelectric energy harvesters particularly for wireless devices and self-powered sensors is highlighted, and the current challenges and future prospects are critically discussed.

Piezoelectric Materials for Energy Harvesting and Sensing Applications: Roadmap for Future Smart Materials

Ethylene-vinyl acetate (EVA) nanocomposites based on halloysite nanotubes (HNT) were prepared by solution casting method. The thermal, mechanical, water uptake, as well as oxygen permeability properties of the nanocomposites were examined. X-ray diffraction (XRD) and field emission scanning electron microscopy showed that HNTs were dispersed well into the EVA matrix. XRD data also suggested that HNT frustrates chain ordering and reduced total crystallinity percentage. The thermal and mechanical properties of the nanocomposites were improved with HNT loading, up to 3 wt%. Both ductility and toughness were enhanced by incorporation of up to 3 wt% of HNT, implicitly confirming that HNT has been dispersed in EVA homogeneously. The addition of HNT also enhanced the water resistance and oxygen permeability of the prepared nanocomposites.

Preparation and characterization of ethylene-vinyl acetate/ halloysite nanotube nanocomposites

Mechanical, thermal and flammability properties of ethylene-vinyl acetate (EVA)/sepiolite nanocomposites

MEMS Applications of NiTi Based Shape Memory Alloys: A Review

Development of polyvinylidene fluoride (PVDF) film composite filled with carbon-based nanomaterials is attracting considerable attention in engineering applications. Numerous studies focus on the enhancement of PVDF properties by adding chemically modified graphene oxide or functionalized carbon nanotubes, or by modifying the polymer chains. On the other hand, in this paper we investigate the nucleation effect of graphene nanoplatelets (GNPs) on morphology and structure of PVDF, without any chemical modification or functionalization either of the GNPs or of the polymer chains. Thus, we fabricate GNP-filled PVDF composite films by the solution casting method. Then, we investigate the effect of GNPs on composite porosity, crystallinity and polymer phases, with special emphasis on the formation of β -phase. To this purpose, the produced PVDF/GNP composite films are characterized through scanning electron microscopy and atomic force microscopy topographies, differential scanning calorimetry, X-ray powder diffraction and Fourier transform infrared spectroscopy. All these experimental characterizations show that GNPs uniformly dispersed in PVDF, without any modification or functionalization, influence significantly the polymer structure and porosity, enhancing the β -phase crystals formation. Finally, the electrical, mechanical and electromechanical properties of the produced PVDF/GNP composite films are characterized.

Hossein Cheraghi Bidsorkhi

Papers

Preparation and characterization of ethylene-vinyl acetate/ halloysite nanotube nanocomposites

Mechanical, thermal and flammability properties of ethylene-vinyl acetate (EVA)/sepiolite nanocomposites

MEMS Applications of NiTi Based Shape Memory Alloys: A Review

Nucleation effect of unmodified graphene nanoplatelets on PVDF/GNP film composites

Gas permeability and permselectivity properties of ethylene vinyl acetate/sepiolite mixed matrix membranes