Effect of crystallinity on the kinetics of liquid absorption into poly(ethylene terephthalate)

摘要

AbstractDrawn poly(ethylene terephthalate) fibers (D.R. 5 : 1) were treated unrestrained in dimethylformamide and benzaldehyde at 100°C for varying amounts of time. A rapid diffusion of liquids into the polymer occurred, the latter experiencing considerable retention of the absorbed liquids at 60°C. The increase in chain mobility brought about by both the liquids absorbed and the liquid‐induced crystallisation that followed allowed orientation strains existing in the polymer structure to be relieved. This brought about a 20 shrinkage in the polymer and a change in its overall geometry. Subsequently, a sharp drop occurred in the level of liquid retention within the polymer signifying expulsion of liquids from the crystallising domains and ultimately a levelling off (equilibrium) in the weight retention kinetics.However, precrystallisation of the fibers at 200°C for 3 h using dry hot air prior to liquid treatment study at 100°C and retention at 60°C, led to a linear increase in the amount of liquid retained in the polymer as a function of time until an equilibrium was established. The essential feature of the latter liquid retention kinetic is that a plot of the amount of relative liquid retained, that isMt/M∞as a function of square root of time, ($ sqrt t $) agrees with Fick's standard diffusion process. © 1993 John Wiley