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:
The charge-strain hysteresis curve can be measured by simple apparatus. While fundamental interpretation of the effect may be complex, the use of the curves for practical purposes such as investigation of fatigue, quality control, differentiation between materials or methods of preparation or surface characteristics, is simple. The effect shows indication of being related to the chemical nature of the material, its composition and structure, and particularly the phase or quasi-phase structure. Chargestrain hysteresis curves have been measured. These are quite reproducible if the samples from which specimens are prepared are uniform. The shape of the hysteresis curve is affected by (1) amplitude of strain, (2) rate of straining, including constant strains, (3) the functional dependence of strain upon time, (4) repeated cycling, (5) incorporation of fillers, (6) incorporation of reinforcing fibers, (7) the mechanical properties of the plastic, (8) detailed composition of the polymers, and (9) temperature. Seven general types of hysteresis curve are observed. The general features of the curve, and the hysteresis area are sensitive methods for detecting slight changes for composition. This method of sample differentiation was illustrated with examples showing the magnitude and sensitivity of the effect. When a sample was held at a given strain, the charge decreased; this suggests that both resistivity, and the initial stages of mechanical plastic flow may be observed indirectly through this phenomenon. Continuously repeated cycling shows a change in charging-strain response related apparently to the initial stages of flexural fatigue. A regular decrease of hysteresis area is observed with repeated cycling, with the area decrease depending upon the plastic composition. The rate of decline of the area with repeated cycling is a second method for differentiating between materials, particularly when differences are obscured in other methods of testing.
Additional Material:
15 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1962.070062204
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