Papers by Keyword: Thermostability

Abstract: Blocked isocyanate – 2-isocyanate-phenylcarbamidemethylbenzene was synthesized and identified using IR-spectroscopy and elemental analysis researching methods. Research showed that adding 2-isocyanate-phenylcarbamidemethylbenzene in rubber compositions based on cis-isoprene synthetic rubber provides increased thermal stability and increasing adhesion comparing them to Manobond-680c.

Abstract: The temperature-time regimes of drying of polyetheretherketone were revealed, during which it is completely possible to get rid of sorption water. The upper limit of the drying temperature is established, above which the thermal stability of polymers deteriorates markedly.

Abstract: Polyarylate (PA, polyoxybenzoyl) is a heat-resistant linear aromatic polyester with a high degree of crystallinity, high physicomechanical and tribotechnical properties that is limited in the possibilities of processing into products. The polymer has low deformability and fluidity in the range of softening temperatures, as well as narrow temperature processing intervals, limited by the destruction temperatures. A promising way to obtain compacts from PA is explosive processing, which ensures the simultaneous realization of high pressure (up to 10 GPa) and temperature (up to 1000 °C). Comparative results of morphology, crystalline and chemical structure and thermomechanical properties of polyarylate after static pressing (SP) and explosive processing (EP) are presented. It was found that EP at the pressure of 2.8 GP, which excludes the destruction and decomposition of polymer compacts, does not cause significant changes to its phase composition, crystalline and chemical structure. The monolithic compacts obtained by EP have higher thermostability and heat deflection temperature than statically compressed ones.

Abstract: The main properties of copolycarbonates on the basis of bisphenols of 1,1-dichloro-2,2-di (4-hydroxy-phenyl) ethylene (S-2), 1,1-dichloro-2,2-di (3,5-dibromo-4-hydroxy-phenyl) ethylene (TB-S-2) and dichlorformiate 4,4'-isopropylidenediphenol are synthesized and studied. Regularities of synthesis of copolymers are determined by method of acceptor and catalytic polyfunctional condensation. The interconnection between their composition, structure and properties is also established. It was shown that copolycarbonates exhibited a high softening point and high heat and flame resistance. The existence of the raw material base for the production of the initial monomers, the improved service properties of copolyesters based on them, and the high technological effectiveness of the proposed synthesis method enabled the copolycarbonates to be regarded as industrially promising polymeric materials.

Abstract: A comparative analysis of the basic physical and chemical properties of non stabilized polyalkyleneterephthalates and their compositions with polymers containing oximates groups is submitted. It is shown that the use of new polyformaloximates (PFO) and polyarylateoximates (PAO) as modifying additives allows improving the operational properties and technical characteristics of polyalkylenetherephthalate compositions.

Abstract: The technological progress constantly raises standards for items operated in rough conditions in order to improve their reliability in a wide range of operating temperatures, fire resistance and sustainability. Researches aimed at discovering flame retardant agents that would help to develop siloxane rubbers with increased fire-resistance are of great scientific interest and have a practical significance. We have studied the effect of aluminium hydroxide on the physical and mechanical properties and fire-resistance of siloxane rubbers. The study has shown that the aluminium hydroxide acts as an effective fire retardant at its content in the rubber over 40 % (wt.), however, it significantly decreases the physical and mechanical properties of the siloxane rubbers and causes difficulties in processing of the rubber mix. The research has shown that the additional introduction of organoclays (5 pts. wt.) improves the fire-resistance of such rubbers, the most effective being montmorillonites modified with alkylbenzyldimethylammonium chloride.

Abstract: In order to improve the thermostability of potassium chlorate particles, microencapsulation method was used to coat potassium chlorate particles. The effects of coating agents on thermostability of coated potassium chlorate particles were investigated by differential thermal analysis (DTA) and optical video microscope. An optimum study of preparation process parameters was carried out by orthogonal design. The results show that the Silane coupling agent kh550 is the most efficient coating agent to inhibit the decomposition of potassium chlorate and result in the improvement of potassium chlorate. The optimal process for the microencapsulation is 5%Silane coupling agent, reaction temperature 40°Cand holding for 3h.

Abstract: This work reports melamine resin was modified with siloxane, Polyvinyl alcohol (PVA) and polyethylene glycol (PEG) to improve its structure and properties, and accomplished a wide research and study on the effect of different reaction conditions, including temperature, PH and solid contents. Using infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and DSC to analyzed the samples and study their composition and performance. The results showed that siloxane, Polyvinyl alcohol and polyethylene glycol (PEG) modifier can make the performance of the melamine better than unmodified ones.

Abstract: Novel polymers with imide and ether were synthesized by pyromellitic dianhydride and Pyromellitic dianhydride (PMDA), 4,4'-metylenedianiline (MDA), amino-teminated polyoxypropylene (D2000). The structures and thermostability of polymer were characterized through FT-IR spectra, thermogravimetric analysis (TGA) and differental scanning calorimetry (DSC), solubility behavior was determined via seven solvents. The results indicate that these polymers have good chemical resistance and exhibit excellent thermostability owing to the introduction of imide units.

Abstract: The mechanism of thermostabilization of the thermostable exo-ß-D-glucosaminidase (Bglph) from Pyrococcus horikoshii was investigated. Conserved domains analysis and C-terminal truncated mutation showed that the C-terminal region was indispensable for the enzymes thermostability. Two site directed mutagenesis proteins (C103A and C103AandC550A) were as active as the native enzyme and showed no structural difference with the native enzyme. By comparison with two mesophilic exo-ß-D-glucosaminidases (CsxA and CsxT) from actinomycetes Amycolatopsis orientalis and fungi Trichoderma reesei respectively, it was shown that the amino acids composition of Bglph was consistent with its high thermostability, hydrophobic interactions, homodimerization and ion pairs could play key roles. These results presented the overall properties of the thermostability of Bglph from diverse aspects.