Effect of Physical Aging on the Bending Recovery of PEEK and PI Films

The relationship between the viscoelasticity and bending recovery responses of PI and PEEK films were studied as well as the effect of physical aging treatment on these properties. The residual elastic modulus ( E r ) and degree of aging of the films were measured from the stress relaxation-recovery...

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Bibliographic Details
Published in:Fibers and polymers 2019, 20(5), , pp.944-950
Main Authors: Kim, Hyo Rin, Lee, Moo Sung, Kee, In Seo, Jung, Soyoun, Kim, Sungmin
Format: Article
Language:English
Subjects:
Aging
Chemistry
Chemistry and Materials Science
Elastic properties
Enthalpy
Glass transition temperature
Modulus of elasticity
Polymer Sciences
Radius of curvature
Recovery
Stress relaxation
Viscoelasticity
섬유공학
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Summary:The relationship between the viscoelasticity and bending recovery responses of PI and PEEK films were studied as well as the effect of physical aging treatment on these properties. The residual elastic modulus ( E r ) and degree of aging of the films were measured from the stress relaxation-recovery experiment using DMA and the enthalpy relaxation endotherms near glass transition temperature using DSC, respectively. The instantaneous bending recovery ratio ( BR + ) of the films was measured from the change in radius of curvature before and after the bending under the condition of 85 °C/85%RH/24 hr. The DMA test was also performed at 85 °C in order to evaluate the progression of the stress relaxation during bending. The E r and BR + values showed good correlation, and higher contributions of elastic response or longer delay of the stress relaxation led to improved bending recovery. Films with BR + values close to zero can be obtained if the conditions of E r
ISSN:1229-9197
1875-0052
DOI:10.1007/s12221-019-8850-y