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:
Stress-strain measurements have been made at a relatively low strain rate (100%/min.) and at relatively high strain rates (approximately 260 × 103%/min.) on a series of high polymeric materials of different chemical composition in textile yarn form. The series comprises the following classes of materials: polyacrylic, polyamide, polyester, polymodacrylic, polyolefin, polypeptide, polyurea, polyurethane, polyvinylidene chloride, rubber, and glass. The yarns, with a few exceptions, were conventional continuous filament, low twist structures of varied filament count and denier. Polyvinylidene chloride was tested both as a monofil and also in the form of a slit film. Polyethylene was tested as a monofil. Two polyurethanes and the rubber were tested as monofils with and without cotton covering. From the results of the stress-strain measurements there were calculated values for the following properties at two strain rates: tenacity and elongation at break, work-to-break, and initial modulus. The effects of increased strain rate on these properties are shown. In general, increased strain rate increases the tenacity and initial modulus. These changes are usually, but not always, accompanied by decreases in elongation at break, so that the work to break may either decrease or increase with increasing strain rate. The physical form in which the yarns were tested (denier, number of filaments, conventional yarns versus slit film type) appeared to have only slight effect on their behavior at different strain rates. However, the chemical nature of the polymer molecules and their physical organization within the yarn filaments both have appreciable effects on yarn behavior at different strain rates. The first effect, that due to chemical nature, is exemplified by silk. The behavior of this natural polypeptide, which contains an appreciable number of side chains attached to the main polymer chain, differs markedly, as the strain rate is increased, from the behavior of polyamides which do not contain such side chains. The side chains evidently tend to keep the main polymer chains apart and thus the interchain forces in the polypeptide differ greatly from the interchain forces in polyamides which do not have such side chains. The second effect, that due to the physical organization (crystallinity and degree of orientation) of polymer molecules within a fiber, is demonstrated by a comparison of the behavior of undrawn and regular nylon at low and high strain rates. The stress-strain behavior of the other polymers in yarn form at different strain rates is discussed in the light of their chemical structure and macromolecular organization.
Additional Material:
34 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1964.070080114
Permalink
