Results are provided for a study of the effect of pitch additions of a different nature on binder properties and refractory material quality in the production of periclase-carbon refractories. The desirability is established of using coal-tar and petroleum pitches as a carbonizing agent for refractory material.

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BNKS paraffinate butadiene-acrylonitrile rubbers (ref. 1) are currently the main type of oil-and petrol-resistant rubbers used in the Russian rubber industry. These rubbers contain insoluble calcium paraffinates. The cold resistance of rubbers compounds based on BNKS is lower in a number of cases than that of compounds based on previously produced SKN butadiene-acrylonitrile rubbers. The aim of the present work was to clarify the reasons for this by investigating the lowtemperature and thermophysical properties of BNKS and SKN rubbers and compounds based on them. The investigation was carried out on BNKS rubber (36 specimens), SKN rubber (3 specimens), and Nipol rubber (2 specimens) with a acrylic acid nitrile (AAN) content of 15.0-21.4 and 25.5-33.5%, and also standard and model compounds based on them. The thermophysical properties at temperatures ranging from-130 to +130°C were studied by means of differential scanning calorimetry (DSC); the results obtained are present in the form of thermograms (the dependence of the heat flux dQ/dt on the scanning temperature). Scanning (heating) was carried out at a rate of 40 K/min. The production of thermograms was preceded by the cooling of specimens at a rate of 320 K/min; in some cases, before cooling, the specimens were preheated at various temperatures. Before the tests, all the specimens were held at room temperature for at least 5 days. The thermograms were used to determine the glass transition temperature T g as the start of the sudden change in specific heat (or dQ/dt) on glass transition, the The authors are in the Scientific Research Institute for Elastomeric Materials and Products (NIIEMI) Open Joint Stock Company, Moscow