Piezoresistivity and strain-sensing behaviour of poly(butylene adipate--terephthalate)/multiwalled carbon nanotube nanocomposites.

Multiwalled carbon nanotubes (MWCNTs) at different concentrations, ranging from 0.5 to 10 wt%, as a conductive filler, were incorporated into poly(butylene adipate--terephthalate) (PBAT), a flexible biodegradable copolyester, melt-mixing, followed by compression moulding. The electrical conductivity of the prepared nanocomposites was evaluated by considering their volume resistivity value.

Influence of Twin Screw Extrusion Conditions on MWCNT Length and Dispersion and Resulting Electrical and Mechanical Properties of Polycarbonate Composites.

The processing conditions were varied during the production of polycarbonate-based composites with the multiwalled carbon nanotubes (MWCNTs) Baytubes C150 P (Bayer MaterialScience AG, Leverkusen, Germany), by melt mixing with an extruder on a laboratory scale. These included the screw design, rotation speed, throughput, feeding position and MWCNT content. Particular attention was paid to the shortening of the MWCNT length as a function of the conditions mentioned.

Elastomeric Sensor-Triboelectric Nanogenerator Coupled System for Multimodal Strain Sensing and Organic Vapor Detection.

Stretchable, flexible sensors are one of the most critical components of smart wearable electronics and Internet of Things (IoT), thereby attracting multipronged research interest in the last decades. Following miniaturization and multicomponent development of several sensors in one could further propel the demand for wireless, multimodal platforms. Greener substitutes to conventional sensors that can operate in a self-powered configuration are highly desirable in terms of all-in-one sensor utilities.

Improvement of the Piezoresistive Behavior of Poly (vinylidene fluoride)/Carbon Nanotube Composites by the Addition of Inorganic Semiconductor Nanoparticles.

Conductive polymer composites (CPCs), obtained by incorporating conductive fillers into a polymer matrix, are suitable for producing strain sensors for structural health monitoring (SHM) in infrastructure. Here, the effect of the addition of inorganic semiconductor nanoparticles (INPs) to a poly (vinylidene fluoride) (PVDF) composite filled with multi-walled carbon nanotubes (MWCNTs) on the piezoresistive behavior is investigated. INPs with different morphologies and sizes are synthesized by a hydrothermal method.

N-Type Coating of Single-Walled Carbon Nanotubes by Polydopamine-Mediated Nickel Metallization.

Single-walled carbon nanotubes (SWCNTs) have unique thermal and electrical properties. Coating them with a thin metal layer can provide promising materials for many applications. This study presents a bio-inspired, environmentally friendly technique for CNT metallization using polydopamine (PDA) as an adhesion promoter, followed by electroless plating with nickel.

Carbon Nanotube-Polyurethane Composite Sheets for Flexible Thermoelectric Materials.

Integration of single-wall carbon nanotubes (SWCNTs) in the form of fabriclike sheets or other preformed assemblies (films, fibers, etc.) simplifies their handling and allows for composites with higher nanotube contents, which is needed to better exploit their outstanding properties and achieve multifunctional materials with improved performance. Here, we show the development of p-type SWCNT-thermoplastic polyurethane (TPU) fabric materials with a wide range of SWCNT contents (from 5 to 90 wt %) by employing a one-step filtration method using a suspension of SWCNTs in a TPU solvent/nonsolvent mixture.

Thermoelectric Properties of Cotton Fabrics Dip-Coated in Pyrolytically Stripped Pyrograf III Carbon Nanofiber Based Aqueous Inks.

The transport properties of commercial carbon nanofibers (CNFs) produced by chemical vapor deposition (CVD) depend on the various conditions used during their growth and post-growth synthesis, which also affect their derivate CNF-based textile fabrics. Here, the production and thermoelectric (TE) properties of cotton woven fabrics (CWFs) functionalized with aqueous inks made from different amounts of pyrolytically stripped (PS) Pyrograf III PR 25 PS XT CNFs via dip-coating method are presented. At 30 °C and depending on the CNF content used in the dispersions, the modified textiles show electrical conductivities (σ) varying between ~5 and 23 S m with a constant negative Seebeck coefficient (S) of -1.

PMMA/SWCNT Composites with Very Low Electrical Percolation Threshold by Direct Incorporation and Masterbatch Dilution and Characterization of Electrical and Thermoelectrical Properties.

In the present study, Poly(methyl methacrylate) (PMMA)/single-walled carbon nanotubes (SWCNT) composites were prepared by melt mixing to achieve suitable SWCNT dispersion and distribution and low electrical resistivity, whereby the SWCNT direct incorporation method was compared with masterbatch dilution. An electrical percolation threshold of 0.05-0.

Unusual nonlinear switching in branched carbon nanotube nanocomposites.

In this experimental study, we investigate the nonlinear dynamic response of nanocomposite beams composed of polybutylene terephthalate (PBT) and branched carbon nanotubes (bCNTs). By varying the weight fraction of bCNTs, we obtain frequency response curves for cantilever specimens under harmonic base excitations, measuring the tip displacement via 3D scanning laser vibrometry. Our findings reveal a surprising nonlinear softening trend in the steady-state response of the cantilevers, which gets switched into hardening for higher bCNT weight fractions and increasing oscillation amplitudes.

Influence of Polyvinylpyrrolidone on Thermoelectric Properties of Melt-Mixed Polymer/Carbon Nanotube Composites.

For thermoelectric applications, both p- and n-type semi-conductive materials are combined. In melt-mixed composites based on thermoplastic polymers and carbon nanotubes, usually the p-type with a positive Seebeck coefficient (S) is present. One way to produce composites with a negative Seebeck coefficient is to add further additives.

Thermoelectric Properties of N-Type Poly (Ether Ether Ketone)/Carbon Nanofiber Melt-Processed Composites.

The thermoelectric properties, at temperatures from 30 °C to 100 °C, of melt-processed poly(ether ether ketone) (PEEK) composites prepared with 10 wt.% of carbon nanofibers (CNFs) are discussed in this work. At 30 °C, the PEEK/CNF composites show an electrical conductivity (σ) of ~27 S m and a Seebeck coefficient (S) of -3.

Polyethylene Glycol as Additive to Achieve N-Conductive Melt-Mixed Polymer/Carbon Nanotube Composites for Thermoelectric Application.

The development of thermoelectric (TE) materials based on thermoplastic polymers and carbon nanotubes is a focus of current TE research activities. For a TE module, both p- and n-conductive composites are required, whereby the production of n-conductive materials is a particular challenge. The present study investigates whether adding polyethylene glycol (PEG) as n-dopant during the melt-mixing of the conductive composites based on polycarbonate, poly(ether ether ketone), or poly(butylene terephthalate) with singlewalled carbon nanotubes (0.

CuCoFeO (x = 0.33, 0.67, 1) Spinel Ferrite Nanoparticles Based Thermoplastic Polyurethane Nanocomposites with Reduced Graphene Oxide for Highly Efficient Electromagnetic Interference Shielding.

CuCoFeO (x = 0.33, 0.67, 1)-reduced graphene oxide (rGO)-thermoplastic polyurethane (TPU) nanocomposites exhibiting highly efficient electromagnetic interference (EMI) shielding were prepared by a melt-mixing approach using a microcompounder.

Nonlinear Thermopower Behaviour of N-Type Carbon Nanofibres and Their Melt Mixed Polypropylene Composites.

The temperature dependent electrical conductivity () and thermopower (Seebeck coefficient) () from 303.15 K (30 °C) to 373.15 K (100 °C) of an as-received commercial n-type vapour grown carbon nanofibre (CNF) powder and its melt-mixed polypropylene (PP) composite with 5 wt.

High-Performance, Lightweight, and Flexible Thermoplastic Polyurethane Nanocomposites with Zn-Substituted CoFeO Nanoparticles and Reduced Graphene Oxide as Shielding Materials against Electromagnetic Pollution.

The development of flexible, lightweight, and thin high-performance electromagnetic interference shielding materials is urgently needed for the protection of humans, the environment, and electronic devices against electromagnetic radiation. To achieve this, the spinel ferrite nanoparticles CoFeO (CZ1), CoZnFeO (CZ2), and CoZnFeO (CZ3) were prepared by the sonochemical synthesis method. Further, these prepared spinel ferrite nanoparticles and reduced graphene oxide (rGO) were embedded in a thermoplastic polyurethane (TPU) matrix.

Highly Tunable Piezoresistive Behavior of Carbon Nanotube-Containing Conductive Polymer Blend Composites Prepared from Two Polymers Exhibiting Crystallization-Induced Phase Separation.

Conductive polymer composites (CPCs) are suitable as piezoresistive-sensing materials. When using CPCs for strain sensing, it is still a big challenge to simultaneously improve the piezoresistive sensitivity and linearity along with the electrical conductivity and mechanical properties. Here, highly tunable piezoresistive behavior is reported for multiwalled carbon nanotube (CNT)-filled CPCs based on blends of two semicrystalline polymers poly(vinylidene fluoride) (PVDF) and poly(butylene succinate) (PBS), which are miscible in the melt.

Blend Structure and n-Type Thermoelectric Performance of PA6/SAN and PA6/PMMA Blends Filled with Singlewalled Carbon Nanotubes.

The present study investigates how the formation of melt-mixed immiscible blends based on PA6/SAN and PA6/PMMA filled with single walled nanotubes (SWCNTs) affects the thermoelectric (TE) properties. In addition to the detailed investigation of the blend morphology with compositions between 100/0 wt.% and 50/50 wt.

Effect of Filler Synergy and Cast Film Extrusion Parameters on Extrudability and Direction-Dependent Conductivity of PVDF/Carbon Nanotube/Carbon Black Composites.

In the present study, melt-mixed composites based of poly (vinylidene fluoride) (PVDF) and fillers with different aspect ratios (carbon nanotubes (CNTs), carbon black (CB)) and their mixtures in composites were investigated whereby compression-molded plates were compared with melt-extruded films. The processing-related orientation of CNTs with a high aspect ratio leads to direction-dependent electrical and mechanical properties, which can be reduced by using mixed filler systems with the low aspect ratio CB. An upscaling of melt mixing from small scale to laboratory scale was carried out.

Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications.

In this work, composites based on epoxy resin and various carbon nanotubes (CNTs) were studied regarding their thermoelectric properties. The epoxy composites were prepared by infiltration of preformed CNT buckypapers. The influence of different types of CNTs on the Seebeck coefficient was investigated, namely lab-made and commercially available multi walled carbon nanotubes (MWCNTs), lab-made nitrogen doped MWCNTs (N-MWCNT) and commercially available single walled carbon nanotubes (SWCNTs).

The force of MOFs: the potential of switchable metal-organic frameworks as solvent stimulated actuators.

We evaluate experimentally the force exerted by flexible metal-organic frameworks through expansion for a representative model system, namely MIL-53(Al). The results obtained are compared with data collected from intrusion experiments while molecular simulations are performed to shed light on the re-opening of the guest-loaded structure. The critical impact of the transition stimulating medium on the magnitude of the expansion force is demonstrated.

"Sliding Crystals" on Low-Dimensional Carbonaceous Nanofillers as Distributed Nanopistons for Highly Damping Materials.

Improving energy dissipation in lightweight polymer nanocomposites to achieve environmentally friendly and mechanically stable structures has reached a limit because of the low-density electrostatic interactions that can be harnessed through the stick-slip mechanism between carbonaceous nanofillers and polymeric chains wrapped around them. In this paper, the atomic friction between the two nanocomposite components is greatly amplified by locally increasing the density of the energetically higher noncovalent bonds. This gives rise to a new material design concept in which crystallite structures, nucleated around the carbonaceous nanofillers, become the source of enhanced energy dissipation.

Tuneable Dielectric Properties Derived from Nitrogen-Doped Carbon Nanotubes in PVDF-Based Nanocomposites.

Nitrogen-doped multiwall carbon nanotubes (N-MWNTs) with different structures were synthesized by employing chemical vapor deposition and changing the argon/ethane/nitrogen gas precursor ratio and synthesis time, and broadband dielectric properties of their poly(vinylidene fluoride) (PVDF)-based nanocomposites were investigated. The structure, morphology, and electrical conductivity of synthesized N-MWNTs were assessed via Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy, and powder conductivity techniques. The melt compounded PVDF nanocomposites manifested significantly high real part of the permittivity (ε') along with low dissipation factor (tan δ) in 0.

Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers.

Melt-mixed composites based on polypropylene (PP) with various carbon-based fillers were investigated with regard to their thermal conductivity and electrical resistivity. The composites were filled with up to three fillers by selecting combinations of graphite nanoplatelets (GNP), carbon fibers (CF), carbon nanotubes (CNT), carbon black (CB), and graphite (G) at a constant filler content of 7.5 vol%.