Polymer drying. II. Replicated time‐studies of molecular desorption from liquid swollen poly(styrene‐co‐divinylbenzene) before and after transition from the gel‐state to the glass‐state

A total of 90 time‐studies were monitored gravimetrically in order to establish the parameters that affect the reproducibility of the kinetic changes that occur sequentially when liquid‐saturated poly(styrene‐co‐divinylbenzene) [poly(Sty‐co‐DVB)] particles, enmeshed in a matrix of polytetrafluroethylene (PTFE) microfibers, are allowed to evaporate to apparent dryness at constant temperature. The test liquids were toluene, chloroform, and acetone. The absorbent samples were made from six different compositions of polymer particles, the DVB mode fractions, x , of which increased from 0.01 to 0.11. The weight, W g , of residual sorbed molecules per gram of polymer at the glass‐transition composition was constant despite the large differences in x . Thereafter the weight of residual sorbed molecules was given by a linear combination of up to six exponential decay functions, which indicated that these molecules were “locked” into six different types of molecular environments (i.e., populations) created by the change from the gel‐state to the glass‐state. The fractions of W g in the populations with the fastest ( k 1 ) and the slowest ( k n ) decay rates were usually less than those with intermediate decay rates. The logarithm of k i in a given time study was a linear function of i , the numerical sequence of decreasing k .