Papers - Archive

Nr 4/2017 - Abstracts

Elastomery nr 4/2017 cover

Vincenzina Barbera, Andrea Bernardi, Giulio Torrisi, Alessandro Porta, Maurizio Galimberti

Controlled functionalization of sp2 carbon allotropes for the reinforcement of diene elastomers

This paper reports functionalization reactions of sp2 carbon allotropes, both nano- and nanostructured, able to introduce heteroatoms such as oxygen and nitrogen, without altering the bulk crystalline organization of the graphitic substrates. sp2 carbon allotropes were: carbon black (CB), nanosized graphite with high surface area (HSAG), multiwalled carbon nanotubes (CNT). Reactions of carbon allotropes were performed with either KOH or hydrogen peroxide or a serinol derivative, 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinolpyrrole, SP), in the absence of solvents or catalysts, by simply donating either thermal or mechanical energy. Sulphur cured composites with HSAG containing hydroxy groups (from the reaction with KOH) revealed better mechanical properties than composites from melt blending with pristine HSAG. CB functionalized with SP was able to promote reduction of Payne effect in compounds based on CB and silica.
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Monika Zielińska, Roger Seyger, Wilma K. Dierkes, Dariusz Bielinski, Jacques W.M. Noordermeer

Swelling of EPDM rubbers for oil-well applications as influenced by medium composition and temperature. Part III. Final experiments and conclusions

The paper focuses on time and temperature dependencies of swelling of crosslinked EPDM in three various solvents: o-xylene, cyclooctane and dodecane and their blends at 22 °C, 40 °C or 60 °C, mimicking the conditions in oil-wells. Sorption experiments of solvents in elastomers provide valuable information on the transport characteristics of the polymer composite, i.e. at what rate the liquid diffuses into the polymer matrix. The rates of the solvent swelling of a crosslinked EPDM sample have been measured in 16 organic solvents at various temperatures. The solvents mass uptake changed in order of: cycloalkanes > aromatic hydrocarbons > alkanes. A better way to determine the solubility parameter of the rubber from swelling in a single solvent, is observation of its swelling behaviour in mixtures of different solvents. In a mixture of solvents, with similar and different molar volumes, the respective components are absorbed by the rubber in the same volume concentration ratio as they were mixed. By mixing two solvents with different interactions towards the EPDM-rubber it is possible to shift the average solubility parameter of the mixture closer to the rubber and then get higher solvent mass uptake than for the pure components. The results show that the extents of the swelling for the pure solvents are nearly independent of temperature within the range studied here (20-80 °C), whereas in case of solvent mixtures at higher temperature, the solubility parameter becomes lower for the EPDM rubber. The interaction between rubber and solvent is the most sensitive and valuable parameter, which determines most prominently the swelling ratio. For the three classes of solvents investigated the solubility parameter approach that of the EPDM rubber, the higher their molar volumes, and consequently the degree of swelling increases.
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Marcin Włoch, Ewa Głowińska, Urszula Ostaszewska, Janusz Datta

Antioxidants used in production of rubber elements. Part II. Current trends with special interest in polymeric antioxidants and antioxidants synthesized using biobased substances

Commonly used in the rubber industry antioxidants are substances derived from petrochemical resources and possess toxicity for human and environment. Designing of novel antioxidants should be connected with the elimination of disadvantages of currently used antioxidants. Presented work contains literature review from 2000 to 2017 in the area of modern antioxidants with the special focus on the polymeric petrochemical antioxidants and bio-based antioxidants (or synthesized using bio-based substances).
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