A systematic dielectric study over a frequency range from 100 Hz to 10 MHz was carried out on ethylene propylene diene monomer rubber (EPDM) mixed with zinc chloride and ammonium iodide with increasing quantities up to 16 and 8 phr, respectively. The measurements were carried out at a room temperature of Ϸ 25°C. Dielectric data were fitted in the frequency domain by using three Fröhlich terms discussing the different relaxation mechanisms in the system. These terms were interpreted according to the crosslinking that is formed by the addition of such materials to EPDM. The thermal aging for such systems was also studied and the data obtained are compared with those done before aging. The mechanical properties as well as the thermal gravimetric measurements were also studied and the data obtained are discussed.
Different samples of cellulose triacetate‐metal ion complexes were prepared from different metal salts. The products were characterized by IR spectroscopy, with emphasis on the complex formation. TGA and DTA of cellulose triacetate (CTA) and its complexes with Ni(II), Co(II), Cu(II) and Cr(III) chlorides were investigated in the temperature range from room temperature to 550°C. The obtained TGA curves show that these samples degrade thermally in three steps, which are attributed to dehydration, fragmentation of the macromolecular structure (the main thermal degradation step), and the carbonization of the product to ash. It is found that the main degradation step follows first‐order kinetics. The complexation of cellulose acetate with metal ions increased its thermal stability. The calculated activation energies varied in the following sequence: CTA‐Cu(II) > CTA‐Ni(II) > CTA‐Co(II) > CTA‐Cr(III) > CTA. This observation was attributed to the electronegativity of the metal ion and the strength of the bond between the cellulose acetate and the metal ion.
The use of cement dust waste as filler in rubber vulcanizates is of great interest as a means to get rid of this waste. The effect of cement dust on the properties of acrylonitrile rubber (NBR) was studied and compared with that of carbon black and kaolin. It was found that the surface treatment of cement dust with fatty acid improves its dispersability. The effect of treated cement dust in combination with carbon black on physico-mechanical, thermal aging, swelling resistance and fatigue resistance of the filled vulcanizates was studied.
If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to study the effect of incorporating some inorganic fillers, namely aluminium oxide and aluminium hydroxide on the rheological, mechanical and thermal behaviour of acrylonitrile-butadiene rubber (NBR) vulcanizates. Design/methodology/approach -For improving physico-mechanical properties of NBR vulcanizates, various compositions were made by incorporating different concentrations of employed fillers with NBR. These properties included the torque, cure time, tensile strength, elongation at break, swelling, diffusivity, as well as thermal behaviour of the loaded and unloaded NBR with fillers were characterised. Findings -The incorporation of the two investigated fillers improves the thermal behaviour of the vulcanizates, especially aluminium hydroxide. All samples showed more or less a first order decomposition kinetics, for which the activation energy ranged from 177 to 187 kg/mol. Research limitations/implications -NBR is extensively used industrially for its single, most important property, which is an exceptional resistance to attack by oils and solvents. However, incorporation of fillers in (NBR) leads to the development of improved, competitive properties of the vulcanizate. A further study must be carried out on the flame retarding effect of the fillers, beside the effect of surface treatment of the fillers on the dispersibility and physico-mechanical properties of the vulcanizates. Practical implications -The use of two investigated fillers provided a simple and practical solution to improving the resistance to swelling in motor and break oil as well as the thermal behaviour of the NBR. Originality/value -The use of these fillers was novel and could be used in many rubber industries especially in gasket and oil seals.
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