Chemical structures thermal stability

Carrasco, E., Pages, P., Gamez-Perez, J., Santana, O.O., Maspoch, M.L. Processing of poly (lactic acid) Characterization of chemical structure, thermal stability and mechanical properties. Polym. Degrad. Stab. 95, 116-125 (2010)... 

Diamantane-based polymers are synthesized to take advantage of their stiffness, chemical and thermal stability, high glass transition temperature, improved solubility in organic solvents, and retention of their physical properties at high temperatures. All these special properties result from their diamantane-based molecular structure [90]. Polyamides are high-temperature polymers with a broad range of applications in different scientific and industrial fields. However, their process is very difficult because of poor solubility and lack of adequate thermal stability retention [90]. Incorporation of 1,6- or... 

Chemical and thermal stabilizers both inactivate the byproducts of degradation processes, preventing them from causing further damage to the polymer. Their chemical structure and mobility in the part define their effectiveness in any given polymeric system. The most common type of chemical stabilizers are antioxidants. 

Ylide complexes of gold are unique in that they exhibit an exceptional chemical and thermal stability, which facilitates preparative and structural work very considerably. It was in this class of compounds that a large variety of true organogold(ll) and mixed valence organogold(l)/(lIl) complexes was discovered. These are rare in the remainder of organogold chemistry. 

Cubic Phase of Boron Nitride c-BN. The cubic phase of boron nitride (c-BN) is one of the hardest materials, second only to diamond and with similar crystal structure. It is the first example of a new material theoretically predicted and then synthesized in laboratory. From automated synthesis a microcrystalline phase of cubic boron nitride is recovered at ambient conditions in a metastable state, providing the basic material for a wide range of cutting and grinding applications. Synthetic polycrystalline diamonds and nitrides are principally used as abrasives but in spite of the greater hardness of diamond, its employment as a superabrasive is limited by a relatively low chemical and thermal stability. Cubic boron nitride, on the contrary, has only half the hardness of diamond but an extremely high thermal stability and inertness. 

In general, polymers with heterocyclic rings as structural element show a high chemical and thermal stability. On the other hand, they are insoluble and infusible, so that they could not initially be used for practical applications in this form. 

One of the technically and commercially most important cation-exchange membranes developed in recent years is based on perfluorocarbon polymers. Membranes of this type have extreme chemical and thermal stability and they are the key component in the chlorine-alkaline electrolysis as well as in most of today s fuel cells. They are prepared by copolymerization of tetrafluoroethylene with perfluorovinylether having a carboxylic or sulfonic acid group at the end of a side chain. There are several variations of a general basic structure commercially available today [11]. The various preparation techniques are described in detail in the patent literature. 

Thus, the principle of the formation of carbocations, clearly shown by Scheme (51), requires judicious choice of both components the source of free radicals should not only be able to dissociate sily - either thermally or photo-chemically - but also exhibit a chemical structure which stabilizes the resultant carbenium ion (e.g. the methoxy groups and an aromatic ring as in Scheme (50). 

Casari, C.S. Li Bassi, A. Ravagnan, L. Siviero, F. Lenardi, C. Piseri, P. Bongiorno, G. Bottani, C.E. Milani, P. Chemical and thermal stability of carbyne-like structures in cluster-assembled carbon films. Phys. Rev. B 2004, 69, 075422-1 to-7. 

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