Graphene thermal conductivity - introduction and latest news - Page 15

JTX (officially Shandong Prosperous Star Optoelectronics Co) demonstrated its graphene-enhanced LED lighting bulbs at the Hong Kong lighting fair. These LED lighting devices use graphene coating that aid in heat dissipation and thus contribute to longer lifetime and better efficiency.

JTX is a relatively new company (established in May 2014 in China) that is involved with the entire LED lighting value chain (from LED chips and filaments to complete light bulbs). In July 2016 JTX was merged with Graphene Lighting PLC that developed the graphene lighting technology in collaboration with Manchester University and the NGI.

Researchers from the Singapore University of Technology and Design (SUTD) have proposed a high-efficiency energy harvesting device based on graphene electrodes and 2D transition metal dichalcogenide materials.

Inspired by the concept of multilayer thermionic devices, the team designed a solid-state thermionic device using van der Waals (vdW) heterostructure sandwiched between two graphene electrodes, to achieve high energy conversion efficiency in the temperature range of 400 to 500 K. The technology enables performance (8% above) of devices comparable to or even better than state-of-art thermoelectric devices around room temperature. This novel design may boost interest in thermionic emission-based energy conversion and pave the way towards another alternative to solutions to low-grade waste heat harvesting.

Researchers from The University of Manchester have conducted a study that presents a review of the three steps of manufacturing graphene/epoxy nano-composites. The possible pre-treatments of nanoparticles before dispersion are introduced, and their influence on the final nanocomposite properties discussed.

SEM images of fracture surface of aligned GNP based epoxy composite

The study stresses interesting results, among which are improvements in various characteristics via the use of GNPs. For instance, an improvement of the thermal diffusivity of 220% was seen when compared to a non-oriented GNP epoxy sample. The work demonstrates how the addition of functionalized graphene platelets to an epoxy resin will allow it to act as electrical and thermal conductor rather than as insulator. The mechanical properties of functionalized GNP/epoxy composites show improvement of the interfacial bond.

Thermal conductivity in graphene is a thriving area of research, thanks to graphene's extraordinary heat conductivity properties and its potential for use in thermal management applications.

Don't miss Graphene-info's new article, that discusses this fascinating topic of heat conductivity in graphene, its potential for heat management applications and more!

Directa Plus, a producer and supplier of graphene-based products for use in consumer and industrial markets, has teamed up with Eurojersey, an Italian producer of technical fabrics under its Sensitive Fabrics brand, to produce a range of fabrics containing the company’s graphene-based products. The new line will focus on high-performance technical fabrics targeting sportswear and underwear sectors.

The companies are conducting joint R&D to further develop the prototype textiles into product samples that will be marketed to the customers of Directa Plus and Eurojersey. The lamination of Sensitive Fabrics with Grafytherm functional membranes containing G+, distributed exclusively by Directa Textile Solutions, reportedly produces a technologically advanced fabric with unique thermal features: the presence of G+ graphene, which is highly thermally conductive, allows a homogeneous distribution of the heat produced by the human body in cold weather and a heat dispersion effect in hot weather.

Researchers at Rice University have found that it may be possible to make graphene-carbon nanotube junctions excel at transferring heat, turning these into an attractive way to channel damaging heat away from next-generation nano-electronics. This could, in theory, be done by putting a cone-like chimney between the graphene and nanotube to eliminate the barrier that blocks heat from escaping.

Graphene and carbon nanotubes both excel at the rapid transfer of electricity and phonons, but when a nanotube grows from graphene, atoms facilitate the turn by forming heptagonal (seven-member) rings instead of the usual six-atom rings. Scientists have determined that forests of nanotubes grown from graphene are excellent for storing hydrogen for energy applications, but in electronics, the heptagons scatter phonons and hinder the escape of heat through the pillars.

Reports out of China state that graphene-based road lighting fixtures are being installed in 28 streets in Beijing, which are said to be up to 30% more energy efficient than current fixtures. These graphene lamps can reportedly reach 140 lumens per watt, which means the new lamps can be much brighter than currently used ones, that produce 110 lumens per watt.

The fixtures' exteriors are made of black and grey composite materials and most of the heat-conducting adhesives and chips inside are said to be produced with graphene. The Chinese official PR mentioned a company called MS Technology but its exact role is not clear. It is said to be "a company focusing on heat dispersing materials research and the firm that first invented graphene lamps that were put into mass production".

Graphene Flagship partner IIT, in collaboration with Italian design company Momodesign, announced the development of a graphene-coated motorcycle helmet that reportedly allows better distribution of impact force. This makes the helmet less susceptible to damage compared to helmets without graphene, even in high temperatures. The result is described as a helmet that improves thermal comfort as well as safety.

In the new helmet, graphene is added into the outer shell as a coating, providing a protective effect to the inner materials of the helmet. This effect was described as a graphene "shelter": the excellent heat-conductive properties of graphene dissipate heat quickly across the helmet, and protect the inner materials from degradation caused by heat.

Exposure Lights, a UK-based company focused on lighting solutions for cycling and outdoor activities, has been showing a graphene-based ‘action camera’ light called ‘Capture‘ at several cycle shows, to compliment GoPro type products primarily, but also as a useful multi purpose pocketable light.

The unit is enclosed in a graphene-enhanced polymer casing, where graphene acts as a heat conductor. It is designed to be waterproof, uses a standard GoPro type battery and has the standard GoPro style mount points. The specifications include a 600 Lumens output, 69g weight including battery, Long burn times with adjustable output and the target RSP is £99.99.

Researchers from Seoul National University and the University of Manchester have found that a graphene coating on biological samples helps dissipate the charge build-up that tends to occur on the surface of these samples during non-destructive electron microscopy imaging. Such build-ups are often damaging and prevent high-resolution images from being obtained.

Currently used gold or platinum coatings mean that researchers cannot obtain high-resolution images of the samples or perform further quantitative and qualitative chemical analyses with techniques such as energy dispersive spectroscopy (EDS). Now, the research team discovered that a layer of graphene on biological samples can dissipate the charge accumulation on the non-conducting surfaces of biological samples thanks to the high electrical conductivity of graphene. The researchers explain that as soon as excessive charges appear on the sample surfaces, the graphene membrane provides conducting channels for these charges to disappear quickly and so allows to obtain high-resolution EM images. Furthermore, the high thermal conductivity of graphene allows it to dissipate excess heat produced by the high-energy electrons in the microscope, thus preventing thermal damage or deformation of biological specimens as well.