Structure and Dynamic Viscoelastic Behavior of Triacetate Fiber

Effect of water and organic solvents on dynamic viscoelasticity of cellulose triacetate fiber (CTAf) was studied comparing with that of regenerated cellulose fibers such as rayon, cupra and lyocell. The peak of the mechanical loss tangent (tan δ: ratio of the storage modulus to loss modulus of viscoelastic materials) was observed during drying process of wet CTAf indicating that glass transition temperature of 193°C in dry state decreased to room temperature in wet state. The same phenomenon has been observed for regenerated cellulose fibers; however, the height of the tan δ peak (tan δmax) for CTAf was lower than those of regenerated cellulose fibers. Tan δmax qualitatively indicates the size of the moving unit suggesting smaller size of the moving unit affected by water for CTAf than those of regenerated cellulose fibers despite quite low crystallnity of CTAf. Organic solvents including both polar and nonpolar solvents induced glass transition for CTAf. n-alkane with relatively large molecular weight, n-nonane and n-decane, also caused glass transition at room temperature for CTAf not for regenerated cellulose fibers.