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Strain recovery of polyester and nylon 66 monofilaments under various temperature histories
Author(s) -
Lunn A. C.,
Lee BL.,
Yannas I. V.
Publication year - 1974
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760140904
Subject(s) - materials science , composite material , quenching (fluorescence) , strain (injury) , polyester , stress relaxation , relaxation (psychology) , glass transition , fiber , stress (linguistics) , nylon 66 , polymer , creep , polyamide , optics , medicine , psychology , social psychology , linguistics , physics , philosophy , fluorescence
Strain recovery of polyester and nylon 66 monofilaments, following stress relaxation at constant strain, has been measured under two types of temperature history. In the first (experiments here called type A), the monofilament, extended at an elevated temperature, was held at constant strain at that temperature, and then air‐quenched to room temperature while still under stress. The stress was later removed with the fiber at ambient temperature, and the recovery from strain determined. In the second (experiments of type B), the monofilament was also extended at an elevated temperature, but it was then allowed to recover, under zero load, at the same temperature, prior to quenching. A cylindrical heater is described which surrounded the fiber specimen and which could be removed suddenly to permit rapid air quenching of the specimen. Recovery was characterized by the percent of applied strain which was recovered 100 sec after load removal. The percent recovery, in type A experiments, decreased to low values with increasing stretch temperature. Recovery in type B experiments, however, was markedly different, and showed a minimum value at stretch temperatures in the vicinity of the glass transition. At higher temperatures, recovery was high, but it decreased rapidly as T M was approached due to the onset of viscous flow. There was thus a discontinuity in recovery behavior as the time of quenching increased through the time of unloading (transition between type A and type B conditions). The results were interpreted to show that the achievement of good heat setting (poor recovery) is critically dependent on the temperature of the fiber during both stretching and recovery periods.