Kinetics of the reverse Diels‐Alder reaction of dicyclopentadienecarboxylate groups on cotton cellulose

Cotton cellulose in the form of fabric has been esterified with dicyclopentadienecarboxylic acid to a degree of substitution of 0.44. The kinetics of the reverse Diels‐Alder reactions of the dicyclopentadienyl groups of the resulting cellulose ester in the presence of trapping agents and of swelling and nonswelling liquids have been measured with the differential scanning calorimeter. Fiber width measurements indicate that the esterified cotton fibers are swollen in the presence of the trapping agents dibutyl maleate, N‐phenylamaleimide, and N‐phenylmaleimide in tetraglyme solution, and in the presence of the nonreactive swelling agents tetraglyme and glycerol. The activation parameters for the dissociations in the swollen fibers are: Ea = 28–33 kcal/mole and ΔS* = −5 to +5 e.u. These kinetic parameters are similar to those previously found for the dissociation of methyl dicyclopentadienecarboxylate in solution. Fiber width measurements indicate that the esterified cotton fibers are collapsed in the dry state and in the presence of paraffin oil, deposited Carbowax 6000, or deposited glyceryl tristearate. The activation parameters for the dissociations in the collapsed fibers are Ea = 18–24 kcal/mole and ΔS* = −20 to −30 e.u. The kinetics are discussed in terms of the state of the cellulose matrix in the swollen and in the collapsed fibers.