ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Nylon 66 and nylon 6 yarns were exposed in air, nitrogen, and vacuum to temperatures form 136 to 215°C. for periods from 5 min. to 17.5 hr. The moisture absorption of both fibers is reduced by the exposure independently of the presence of oxygen or of antioxidant. This is ascribed to secondary crystallization. Simultaneously, the electrical resistivity is increased. The breaking strength is reduced by exposure in the presence of oxygen unless the polymer contains antioxidant. The extent of oxidative cleavage was measured by the viscosity-average molecular weight M̄v of nylon 66. Simultaneously, a reduction of the amine endgroup content was observed. It occurs only in the presence of oxygen and approaches a limit indicating that some amine groups are not subject to elimination. If oxygen is absent or the polymer protected by antioxidant, the M̄v increases. Sorption of hydrochloric acid is reduced by the exposure. Only 80% of the amine groups in the unexposed and 55% in the exposed nylon participate in acid binding at pH 2.5. The rate constants of cleavage as manifested by M̄v and of the process leading to disappearance of amine groups were determined for nylon 66. The activation energies were calculated 40 and 36 Kcal./mole, respectively.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1965.070090820
