It is difficult to imagine modern life without plastics. Look around you, they are everywhere: pens, PC’s, lenses, furniture, etc. They are cheap, long-lasting and light and, moreover, they have good mechanical, thermal and dielectric properties, to such an extent that they have replaced wood, metal or glass in many applications. The polysulphone, phenoxyl or polycarbonate thermoplastics studied in this thesis are highly resistant (the last one being used for car fenders), ductile and flexible.
The quid of the question is that these interesting properties at a macroscopic scale (the ordinary, everyday-life scale) depend on: 1) the structure of the polymer chains and 2) the movements of their component molecules and atoms at a microscopic scale (the scale of atoms). Despite the fact that, on sight, a card (for example) does not “move", the atoms in its interior are continually moving and we would be able to see this if we had a giant magnifying glass. In this study the “glass” used was a technique known as neutron dispersion (NS). By means of NS the relative position of atoms can be known and the movement studied of these small particles, the neutrons, and how they are deviated from their trajectory on passing through the material studied below.
The existence of a direct correlation between the mechanical properties of a thermoplastic and the phenomenon known as Secondary Relaxations has been known for some time amongst the scientific community. Regarding the latter, although it is known that they are linked with the movement of molecules in general, in the majority of cases their exact origin and nature are not known, i.e. exactly how atoms and molecules move and/or the factors that determine that the same molecule in some cases moves and in others does not. In particular, thermoplastics that contain phenyl rings present prominent secondary relaxations and are quite similar amongst each other. Thus, the idea was, through NS techniques, to study the movement of these rings in various thermoplastics (the three previously mentioned), in order to subsequently compare these movements with secondary relaxation phenomena. The phenyl rings are flat and rigid structures (like a coin) that unite the two ends of the principal plastic chain in such a way that the final result is a species of “a necklace of coins”. The peculiarity of the set of materials chosen is that, in each case, the interlinking rings on the chain are separated by different, more or less large and flexible molecular units. That is to say, following on with the metaphor of the “necklace”, different sized and coloured “beads” are inserted between the coin structures.
Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1
21.03.2018 | Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik FHR
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21.03.2018 | American Institute of Physics
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
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