SYNOPSISPoly(ethy1ene terephthalate) fibers were aminolyzed in n-butylamine vapor and aqueous n-butylamine. Both aminolysis reactions resulted in weight loss, reduction of molecular weight and tensile strength, and some increase in density. After extraction in chloroform, weight loss of the aminolyzed samples increased due to removal of oligomers which had not been removed during aminolysis or rinsing. Differences between vapor and aqueous aminolysis are discussed in terms of previously described stages of aminolysis. Scanning electron photomicrographs revealed that the surface of vapor-aminolyzed fibers developed axial cracks while the surface of aqueous-aminolyzed fibers contained cracks in the radial direction.

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SYNOPSISThe specific surface area (SSA) of delustered undrawn and drawn high-speed spun PET fibers hydrolyzed in aqueous NaOH was measured using three methods: (1) geometric, based on fiber diameter; (2) gas adsorption using N2 and the BET equation; and (3) adsorption of a nonionic surfactant. Increasing the spinning speed had little effect on the SSA of the untreated fibers, while drawing resulted in considerably larger SSA. For the hydrolyzed fibers, both adsorption methods resulted in larger SSAs than that predicted geometrically due to surface pitting. After hydrolysis, the higher spinning speed resulted in a greater increase in SSA over the untreated sample, whereas the increase in SSA was less for the drawn fibers compared to the undrawn. The kinetics of hydrolysis are also discussed. 0 1995 John Wiley & Sons, Inc.

Poly(ethylene terephthalate) fibers have been aminolyzed in aqueous n-butylamine and n-butylamine vapor. Aqueous aminolysis causes short cracks to form perpendicular to the fiber axis, whereas vapor aminolysis results in continuous cracks parallel to the fiber axis. At a given treatment time or molecular weight, the breaking load of the vapor aminolyzed fibers is less than that of the fibers aminolyzed in aqueous amine. The differences in strength are considered in light of Prevorsek's model of melt-spun fibers. The amine vapor apparently breaks primarily extended chain tie molecules, and the attack of the aqueous amine is concentrated in unoriented amorphous regions. Scanning electron photomicrographs of fractured fiber ends and fibers stressed to 60, 75, and 90% of their mean breaking load provide further evidence of the different locations of attack.