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

Over the past four decades, global plastics production has quadrupled1. If this trend were to continue, the GHG emissions from plastics would reach 15% of the global carbon budget by 20502. Strategies to mitigate the life-cycle GHG emissions of plastics, however, have not been evaluated on a global scale. Here, we compile a dataset covering ten conventional and five bio-based plastics and their life-cycle GHG emissions under various mitigation strategies. Our results show that the global life-cycle GHG emissions of conventional plastics were 1.7 Gt of CO2-equivalent (CO2e) in 2015, which would grow to 6.5 GtCO2e by 2050 under the current trajectory. However, aggressive application of renewable energy, recycling and demand-management strategies, in concert, has the potential to keep 2050 emissions comparable to 2015 levels. In addition, replacing fossil fuel feedstock with biomass can further reduce emissions and achieve an absolute reduction from the current level. Our study demonstrates the need for integrating energy, materials, recycling and demand-management strategies to curb growing life-cycle GHG emissions from plastics. The life-cycle GHG emissions from plastics are expected to increase. Here, it is shown that an aggressive strategy of decarbonizing energy infrastructure, improving recycling, adopting bio-based plastics and reducing demand is required to keep emissions below 2015 levels.

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Strategies to reduce the global carbon footprint of plastics

Carbon nanotubes (CNTs) are regarded as ideal filler materials for polymeric fiber reinforcement due to their exceptional mechanical properties and 1D cylindrical geometry (nanometer-size diameter and very high aspect ratio). The reported processing conditions and property improvements of CNT reinforced polymeric fiber are summarized in this review. Because of CNT polymer interaction, polymer chains in CNTs’ vicinity (interphase) have been observed to have more compact packing, higher orientation, and better mechanical properties than bulk polymer. Evidences of the existence of interphase polymers in composite fibers, characterizations of their structures, and fiber properties are summarized and discussed. Implications of interphase phenomena on a broader field of fiber and polymer processing to make much stronger materials are now in the early stages of exploration. Beside improvements in tensile properties, the presence of CNTs in polymeric fibers strongly affects other properties, such as thermal stabi...

Polymer/Carbon Nanotube Nano Composite Fibers–A Review

The fabrication and characterization of fi bers that are ultrastretchable and have metallic electrical conductivity are described. The fi bers consist of a liquid metal alloy, eutectic gallium indium (EGaIn), injected into the core of stretchable hollow fi bers composed of a triblock copolymer, poly[styreneb -(ethylene- co -butylene)- b -styrene] (SEBS) resin. The hollow fi bers are easy to mass-produce with controlled size using commercially available melt processing methods. The fi bers are similar to conventional metallic wires, but can be stretched orders of magnitude further while retaining electrical conductivity. Mechanical measurements with and without the liquid metal inside the fi bers show the liquid core has a negligible impact on the mechanical properties of the fi bers, which is in contrast to most conductive composite fi bers. The fi bers also maintain the same tactile properties with and without the metal. Electrical measurements show that the fi bers increase resistance as the fi ber elongates and the cross sectional area narrows. Fibers with larger diameters change from a triangular to a more circular cross-section during stretching, which has the appeal of lowering the resistance below that predicted by theory. To demonstrate their utility, the ultrastretchable fi bers are used as stretchable wires for earphones and for a battery charger and perform as well as their conventional parts.

/pdf/ultrastretchable-fibers-with-metallic-conductivity-using-a-2cc35ept4q.pdf

Ultrastretchable Fibers with Metallic Conductivity Using a Liquid Metal Alloy Core

Future plastic materials will be very different from those that are used today The increasing importance of sustainability promotes the development of bio-based and biodegradable polymers, sometimes misleadingly referred to as ‘bioplastics’ Because both terms imply “green” sources and “clean” removal, this paper aims at critically discussing the sometimes-conflicting terminology as well as renewable sources with a special focus on the degradation of these polymers in natural environments With regard to the former we review innovations in feedstock development (eg microalgae and food wastes) In terms of the latter, we highlight the effects that polymer structure, additives, and environmental variables have on plastic biodegradability We argue that the ‘biodegradable’ end-product does not necessarily degrade once emitted to the environment because chemical additives used to make them fit for purpose will increase the longevity In the future, this trend may continue as the plastics industry also is expected to be a major user of nanocomposites Overall, there is a need to assess the performance of polymer innovations in terms of their biodegradability especially under realistic waste management and environmental conditions, to avoid the unwanted release of plastic degradation products in receiving environments

Environmental performance of bio-based and biodegradable plastics: the road ahead

Recycling of bioplastics, their blends and biocomposites: A review

Melt blending of carbon nanotubes/polyaniline/polypropylene compounds and their melt spinning to conductive fibres

Recording high quality biosignals by dry textile electrodes is a common challenge in medical health monitoring garments. The aim of this study was to improve skin–electrode interface and enhance th ...

/pdf/surface-modification-of-textile-electrodes-to-improve-5173vmmino.pdf

Azadeh Soroudi

Papers

Recycling of bioplastics, their blends and biocomposites: A review

Melt blending of carbon nanotubes/polyaniline/polypropylene compounds and their melt spinning to conductive fibres

Surface modification of textile electrodes to improve electrocardiography signals in wearable smart garment

Electro-conductive composite fibers by melt spinning of polypropylene/polyamide/carbon nanotubes

Electrode placement in electrocardiography smart garments: A review.