Molecular Fraction Behavior in Oriented Polymers.
Abstract
Fracture in polymers of fibrous morphology is accompanied by covalent bond scission. Gel permeation chromatography (GPC) was used to monitor the changes in molecular weight distribution upon fracture in nylon 6 fibers. The bond rupture of 2.3 x 10 to the 18th power per cu cm measured from GPC is approximately five times the number of free radicals observed on fracture using electron spin resonance (ESR). GPC results showed that the high molecular weight component of the molecular weight distribution ruptures preferentially. Fourier transform infra-red spectroscopy (FTIS) observation of virgin, fractured, ground, and irradiated nylon 6 fiber specimens provided additional evidence supporting the results of GPC and ESR. A quantitative measure of the bond rupture could not be obtained from FTIS measurements. Some calculations for the structure of the fibrous morphology were performed: (1) Calculation for the number of tie molecules per gram. This was found to be approximately 1 x 10 to the 20th power per gram in nylon 6 fibers. (2) Calculation for the contribution of various amorphous components like cilia, chain loops (folds), chain ends, and tie chains. (3) A model for the distribution of the tie chain lengths. The experimental results of GPC and some of the calculations above were used to review the morphology and the fracture behavior of the fibrous structure. A new mechanism for the formation of submicroscopic cracks in stressed fibers is proposed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1980
- Accession Number
- ADA092241
Entities
People
- David K. Roylance
- Rakesh K. Popli
Organizations
- Massachusetts Institute of Technology