Thermoplasticity of acetylated cotton yarn as influenced by degree of substitution, temperature, and other factors

Abstract

synopsisThe relative degree of thermoplasticity of acetylated cotton yarns has been deteimined by a technique developed for the purpose. The interfering contribution of hydrogen bonding could be eliminated by a wetting-out process. The yarns were acetylated to degrees of substitutions ranging from 0.77 to 2.93. Heat setting was applied either in vacuum or at atmospheric pressure in the presence of water vapor a t temperatures in the range of 110-225OC. The thermoplasticity observed over a period of 30 days was permanent but readily removable by another application of heat setting. The effect of degree of substitution upon thermoplasticity could be represented by sigmoidal curves beginning at about DS = 1 and increasing rapidly and asymptotically to a maximum a t about DS = 2.25. In vacuum or water vapor the maximum thermoplastic response occurred a t 175"C., but the response was greater with water vapor. Under vacuum heating a very distinct minimum response occurs a t 18OoC., due to second-order transition effect. Upon heating in the presence of water vapor a distinct minimum response occurs at 200°C. with secondary minima at 150 and 120'C. Prior crystallization (by heating to 200-225°C.) greatly reduces thermoplasticity due to reduction of the amorphous component, but does not completely eliminate it.

Biopolymer Coatings for Paper and Paperboard

“…The thermoplastic characteristics of cellulose acetate are greatly improved as the acetyl content is increased from $ 20% to $ 39% [80]. Higher acetyl content gives better moisture resistance; lower acetyl content gives better impact strength.…”

“…The polysaccharide polymers in particular will be highlighted in this review. Biopolymer films for use as packaging materials based on starch [33][34][35][36][37][38], chitosan [57][58], cellulose derivatives [63,[77][78][79][80][81][82], and hemicelluloses [43][44][45][46] are described in detail in the literature. Bio-based materials have also been used, for example, in composite formulations (e.g., starch/low-density polyethylene (LDPE) blends) [24,25].…”