Effect of Temperature on Gelation Properties of Cellulose Derivatives.

Nova Southeastern University, Davie, Florida, USA

Objective. The study was conducted to determine gelation properties of methyl cellulose (MC), and carboxymethylcellulose (CMC) in comparison with poly(ethylene oxide) (PEO) when subjected to near-boiling temperatures during abuse. Background. PEO-based abuse deterrent formulations can become vulnerable due to physicochemical changes that occur in solid and solution states of the polymer when subjected to heat. Cellulose derivatives, whose viscosities are minimally affected and gelation properties are enhanced at high temperatures can be beneficial. Therefore, in this study, we characterized these properties at near-boiling extraction temperatures. Methods. A texture analyzer (Brookfield, CT3) was used to measure the gel strength of PEO, CMC and MC solutions (0.5, 1, 2, 2.5, and 5% w/v). Each polymer sample solution was poured into a jacketed beaker maintained at 90oC. After 5 min, gel strength was measured by allowing the texture analyzer probe to travel into the sample to 10 mm at a speed of 1 mm/sec. As the probe moved into the sample, the resistance (measured in mN) exercised by the sample was recorded. Results. PEO solutions showed the maximum gel strength of 196 mN (5% w/v) at room temperature, which was decreased to 76.6 mN at high temperature. MC (5% w/v) solution displayed lowest gel strength at room temperature, whereas at high temperature, it showed the highest gel strength of 1049 mN. Conclusion. At elevated temperatures, where PEO and CMC solutions lose their integrity, the MC solution become strong due to thermo-gelation. Therefore, combinations of such polymers can be helpful in maintaining deterrence performance at low and elevated temperatures.