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.
Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst
Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy