Anomalous penetrant transport in glassy polymers VI. Effect of temperature on transport

Abstract

AbstractTransport of liquid cyclohexane through well characterised, initially glassy, crosslinked polystyrene slabs was Investigated at 20, 30, 40, and 50°C. The samples used were produced by bulk polymerization of styrene and divinyl benzene (DVB) at 90°C for 43 hr using benzoyl peroxide as an initiator. The samples tested had initial cross‐linking ratios, X, between 5 and 25 × 10−3 mol DVB/mol styrene. The initial thickness of the samples tested varied from 0.25 mm to 1.80 mm, and the aspect ratio (length to thickness ratio) was maintained above 10;1 in order to analyze the results by one‐dimensional transport equations. Cyclohexane uptake was followed as a function of time along with dimensional changes in the thickness and area of the samples. The results of penetrant uptake as a function of time were analyzed using a simplified exponential expression and employing all the data points from the beginning of the experiment until the time of observation of the maximum in uptake. Good correlations were established between the penetrant uptake and the transport temperature. These results were interpreted in terms of competitive relaxational and diffusional mechanisms.