Swelling of Synthetic Rubbers in Mineral Oils

Abstract

The swelling of compositions from typical oil-resistant rubbers has been measured in hydrocarbons having a wide range of solvent power. Compositions loaded with the same volume of SRF carbon black and no extractable softeners have been studied at 25", 70", and 100°C.The aniline point of the hydrocarbon measures the tendency to swell, and up to 100% swelling the logarithm of the volume increase varies inversely with the aniline point of the oil. Swelling was found to be greatest with the composition from Neoprene GN and was progressively lower with those from Stance Perbunan, Hycar OR-15, and Thiokol FA. The swelling was found to increase as temperature was raised, but the rate of increase was different with the various synthetic rubbers. Changes in composition during test may be responsible for these differences. Consideration of these results and published data indicates that the slope of the log swelling-aniline point plots of compositions from a particular synthetic rubber does not change with temperature, loading, or degree of cure. There is apparently a small difference in the slope as the type of

Thickness of the Ice-Shedding Lubricant Layer in Equilibrium with an Underlying Cross-Linked Polymer Film

“…While the theoretical results of Figure 2 and prior experimental data 31 suggest the possibility for preparing a smart thermoresponsive coating that releases oil only at low temperatures, the data of Figure 2 further teach on how to finetune the temperature for this single-layer to two-layer transition. According to Figure 2, this transition may occur for a given system over a χ range of 0 and ∼0.25, corresponding to a wide temperature range, by simply changing either h s,0 /h 0 or x s .…”

“…That more lubricant is released as χ increases or temperature decreases should not be surprising. For example, Powers and Billmeyer determined the equilibrium amounts of oils sorbed by four different rubbers at 25, 70, and 100 °C, respectively. The sorbed oil amount decreased as the temperature dropped regardless of the oil and rubber combination.…”

Polysulfide Polymers

“…The polysulfide polymers are outstanding for solvent and oil resistance (28, SO, 38,51,53), impermeability to vapors and gases (38,52), and resistance to oxygen, light, and ozone (39, 41, 4®, 84)• They do not have high tensile strength or abrasion resistance, but are suitable, in general, for mechanical rubber goods. Disadvantages often cited against them have been odor and poor compression set resistance.…”

Natural and Synthetic Rubbers

“…Powers and Billmeyer (164) discovered that the logarithm of the percentage swelling varies inversely with the aniline point up to 100% swelling, and therefore believe that the slope of the swelling curve is a fairly satisfactory index for identification of the type of synthetic rubber. About the same time Parker (160) published an article on the identification of raw and vulcanized rubberlike polymers by determining their swelling ratios at 25 °C.…”