Chemical Stress Cracking of Acrylic Fibers.
Abstract
The generation of periodic microscopic transverse cracks in oriented acrylic fibers immersed in hot alkaline hypochlorite solution is described in detail and shown to be a variety of chemical stress cracking. It is greatly accelerated by external tensile stress, high fiber permeability, moderate fiber orientation, and water-plasticization. The proposed mechanism for bond cleavage involves cyclization of nitrile groups (similar to the 'prefatory reaction' in pyrolysis of acrylic fibers), followed immediately by N-chlorination and chain scission. Mechanical retractile forces (internal or external) then cause chain retraction and crack growth. Despite the remarkable regularity of the crack pattern, which typically resembles a series of stacked lamellae, the process is independent of any such underlying fiber morphology. The cracking process does, however, appear to be a sensitive indicator of residual latent strain in the fiber, which may persist even after high-temperature annealing. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1982
- Accession Number
- ADA114555
Entities
People
- D. R. Uhlmann
- J. Herms
- L. H. Peebles Jr.
Organizations
- Massachusetts Institute of Technology