For much the same reason LCD televisions offer eye-popping performance, a thermomagnetic processing method developed at the Department of Energy’s Oak Ridge National Laboratory can advance the performance of polymers.
Polymers are used in cars, planes and hundreds of consumer products, and scientists have long been challenged to create polymers that are immune to shape-altering thermal expansion. One way to achieve this goal is to develop highly directional crystalline structures that mimic those of transparent liquid crystal diode, or LCD, films of television and computer screens.
The high magnetic field environments are provided by fully recondensing commercial prototype superconducting magnet processing system. The electromagnetic fields turn and align the liquid crystal phase forming a pseudo super-structure of ordered domains. This leads to advanced physical properties such as near-zero coefficient of thermal expansion.
Unfortunately, polymers typically feature random microstructures rather than the perfectly aligned microstructure – and transparency – of the LCD film.
ORNL’s Orlando Rios and collaborators at Washington State University have pushed this barrier aside with a processing system that changes the microstructure and mechanical properties of a liquid crystalline epoxy resin.
Their finding, outlined in a paper published in the American Chemical Society journal Applied Materials and Interfaces, offers a potential path to new structural designs and functional composites with improved properties.
The method combines conventional heat processing with the application of powerful magnetic fields generated by superconducting magnets. This provides a lever researchers can use to control the orientation of the molecules and, ultimately, the crystal alignment.
“In this way, we can achieve our goal of a zero thermal expansion coefficient and a polymer that is highly crystalline,” said Rios, a member of ORNL’s Deposition Science Group. “And this means we have the potential to dial in the desired properties for the epoxy resin polymers that are so prevalent today.”
Epoxy is commonly used in structural composites, bonded magnets and coatings. Rios noted that thermosets such as epoxy undergo a chemical cross-linking reaction that hardens or sets the material. Conventional epoxy typically consists of randomly oriented molecules with the molecular chains pointing in every direction, almost like a spider web of atoms.
“Using thermomagnetic processing and magnetically responsive molecular chains, we are able to form highly aligned structures analogous to many stacks of plates sitting on a shelf,” Rios said. “We confirmed the directionality of this structure using X-ray measurements, mechanical properties and thermal expansion.”
Co-authors of the paper, “Thermomagnetic processing of liquid crystalline epoxy resins and their mechanical characterization using nanoindentation,” are Yuzhan Li and Michael Kessler of Washington State’s School of Mechanical and Materials Engineering.
The ORNL portion of the research was supported by the Critical Materials Institute, an Energy Innovation Hub funded by DOE’s Office of Energy Efficiency and Renewable Energy. Washington State’s research was funded by the Air Force Office of Scientific Research.
UT-Battelle manages ORNL for the Department of Energy's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/
Ron Walli | EurekAlert!
Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)
Successful Mechanical Testing of Nanowires
07.12.2017 | Helmholtz-Zentrum Geesthacht - Zentrum für Material- und Küstenforschung
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences