Effect of alcoholic, glycolic, and polyester resin additives on the gelation of dilute solution (1%) of methylcellulose

The effect of various additives, such as alcohols, glycols, and polyester resins on the gel temperature of dilute solutions (1% by weight) of methylcellulose (MC) has been studied. The gel temperatures of 1% MC solution with all the used additives except polyvinyl alcohol (PVA) were higher than that of the pure 1% MC solution, which is 50 degreesC. The gel temperature increased with r (r is a ratio of wt% of additives to that of MC), reached a maxima followed by a decrease for succinic, octane dioic, azeilic, and pimelic acid based polyester. In addition to this variation pattern in gel temperature, phase separation succeeded at higher r values on the addition of polyvinyl and benzyl alcohol, ethanol, propanol, butyl cellosolve, and polyethylene glycol. But for ethylene, diethylene and tetraethylene glycols, the gel temperature continuously increased with r, followed by the phase separation. The increase in gel temperature induced by the used additives except PVA is suggested to be the effect of the predominance of pseudo-surfactancy over co-solvency. (C) 2003 Elsevier Science Ltd. All rights reserved.