Highly conductive carbon nanotube-graphene hybrid yarn

An efficient procedure for the fabrication of highly conductive carbon nanotube/graphene hybrid yarns has been developed. To start, arrays of vertically aligned multi-walled carbon nanotubes (MWNT) are converted into indefinitely long MWNT sheets by drawing. Graphene flakes are then deposited onto the MWNT sheets by electrospinning to form a composite structure that is transformed into yarn filaments by twisting. The process is scalable for yarn fabrication on an industrial scale. Prepared materials are characterized by electron microscopy, electrical, mechanical, and electrochemical measurements. It is found that the electrical conductivity of the composite MWNT-graphene yarns is over 900 S/cm. This value is 400% and 1250% higher than electrical conductivity of pristine MWNT yarns or graphene paper, respectively. The increase in conductivity is asssociated with the increase of the density of states near the Fermi level by a factor of 100 and a decrease in the hopping distance by an order of magnitude induced by grapene flakes. It is found also that the MWNT-graphene yarn has a strong electrochemical response with specific capacitance in excess of 111 Fg-1. This value is 425% higher than the capacitance of pristine MWNT yarn. Such substantial improvements of key properties of the hybrid material can be associated with the synergy of MWNT and graphene layers in the yarn structure. Prepared hybrid yarns can benefit such applications as high-performance supercapacitors, batteries, high current capable cables, and artificial muscles

Radiation Characterization of a 0.11 micrometer Modified Commercial CMOS Process

This viewgraph presentation reviews the tests of a modified commercial CMOS chip for operation in radiation environments. The presentation has pictures of the chip, and charts of the test results

Wet-Spun Biofiber for Torsional Artificial Muscles

The demands for new types of artificial muscles continue to grow and novel approaches are being enabled by the advent of new materials and novel fabrication strategies. Self-powered actuators have attracted significant attention due to their ability to be driven by elements in the ambient environment such as moisture. In this study, we demonstrate the use of twisted and coiled wet-spun hygroscopic chitosan fibers to achieve a novel torsional artificial muscle. The coiled fibers exhibited significant torsional actuation where the free end of the coiled fiber rotated up to 1155 degrees per mm of coil length when hydrated. This value is 96%, 362%, and 2210% higher than twisted graphene fiber, carbon nanotube torsional actuators, and coiled nylon muscles, respectively. A model based on a single helix was used to evaluate the torsional actuation behavior of these coiled chitosan fibers

Application of mixture experimental design to optimize formulation and performance of thermoplastic road markings

The influence offormulation components on the physical, mechanical and optical properties of hot melt thermoplastic road markings was studied. To minimize the number of experiments, mixture method was used as an effective tool for experimentaldesign. Binder (rosin ester and hydrocarbon based resins), pigment (TiO2), filler (talc) and plasticizer (long oil alkyd resin and dibutyl phthalate) were taken into consideration as the key factors at different levels. A range offormulations were prepared by melt blending of variables and other required components. Softening point temperature (Tsp) and its changes (ΔTsp), Taber abrasion resistance, color difference (ΔE) before and after exposure to the accelerated weathering conditions and heat stability test, were chosen as the key responses. A window of optimum end-use properties of thermoplastic road marking formulations was narrowed down within the range of desired responses in quadratic model using DX v.7.1.3 program. The results showed that the optimized formulations were very close to those from the regression analysis, and the mixture experimental design was an effectual method to optimize the composition of a thermoplastic road marking formulation with respect to its properties. The precision of the model was evaluated by preparing two samples in the optimized window and comparing the predicted and actual properties. The results showed a good agreement between the proposed model and experimental measurements

Corrosion performance of epoxy coatings containing silane treated ZrO2 nanoparticles on mild steel in 3.5 % NaCl solution

Clear epoxy coatings were modified by adding various levels of ZrO2 nanoparticles. In order to achieve proper dispersion of nanoparticles in the epoxy-based coating and making possible chemical interactions between nanoparticles and polymeric coating, the surface of the nanoparticles was treated with aminopropyl trimethoxy silane (APS). Corrosion performance of mild steel coated specimens was investigated employing EIS, electrochemical noise (ECN) techniques and salt spray test. Coatings with 2–3 wt% ZrO2 nanoparticles possessed the best corrosion performance among the coating specimens. Possible chemical interactions between polymeric matrix and treated nanoparticles in nanocomposites cause high barrier properties and ionic resistance

Blending of Hydrocarbon and Rosin Ester-basedResins to Study its Effect on the Physical andMechanical Properties of Thermoplastic Road Markings

In this study, the effect of hydrocarbon and rosin ester resins combination on the physical and mechanical properties of thermoplastic road markings were evaluated. At first, two basic thermoplastic road marking formulations based on hydrocarbon and rosin ester resins were prepared. Several samples of the blends of two basic formulations for thermoplastic road marking were characterized and compared by their softening points, abrasion resistance, color data changes, DMTA and tensile strength values. The results showed that hydrocarbon-based thermoplastic road markings have better weathering resistance and rosin ester based materials illustrated enhanced heat resistance. The inclusion of rosin ester thermoplastic road marking into the hydrocarbon-based formulations, improves compatibility of the hydrocarbon resin and dibutyl phthalate ()DBP)(, as well as their physical and mechanical properties. The unique properties of rosin arise from its hydrophobic chain skeleton and its hydrophilic carboxy groups which contribute to its excellent solubility and compatibility with a variety of other synthetic resins. The best performance was obtained with 50 wt % inclusion of rosin ester to hydrocarbon based compound. DMTA analysis revelation with combination of hydrocarbon and rosin ester-based road markings showed that the decreasing trend in elastic modulus is shifted to higher temperature, and as a result it keeps the hardness and ductile properties of thermoplastic road markings unchanged. More favored raw materials for compatibilization of compounds in road marking formulations lead to higher elongation- at-break and an increased toughness

Knitted carbon-nanotube-sheath/spandex-core elastomeric yarns for artificial muscles and strain sensing

Highly stretchable, actuatable, electrically conductive knitted textiles based on Spandex (SPX)/CNT (carbon nanotube) composite yarns were prepared by an integrated knitting procedure. SPX filaments were continuously wrapped with CNT aerogel sheets and supplied directly to an interlocking circular knitting machine to form three-dimensional electrically conductive and stretchable textiles. By adjusting the SPX/CNT feed ratio, the fabric electrical conductivities could be tailored in the range of 870 to 7092 S/m. The electrical conductivity depended on tensile strain, with a linear and largely hysteresis-free resistance change occurring on loading and unloading between 0% and 80% strain. Electrothermal heating of the stretched fabric caused large tensile contractions of up to 33% and generated a gravimetric mechanical work capacity during contraction of up to 0.64 kJ/kg and a maximum specific power output of 1.28 kW/kg, which far exceeds that of mammalian skeletal muscle. The knitted textile provides the combination of strain sensing and the ability to control dimensions required for smart clothing that simultaneously monitors the wearer\u27s movements and adjusts the garment fit or exerts forces or pressures on the wearer, according to needs. The developed processing method is scalable for the fabrication of industrial quantities of strain sensing and actuating smart textiles