An instrument for environmental control of vapor pressure and temperature for tensile creep and other mechanical property measurements

Review of Scientific Instruments

Volumn 78, Issue 10, 2007, Pages

  Majsztrik, P W ^a   Bocarsly, A B ^a   Benziger, J B ^b  

^a PRINCETON UNIVERSITY   (United States)

^b Princeton University   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ELASTIC MODULI; IONOMERS; MOLECULAR DYNAMICS; POLYMERS; PROTON EXCHANGE MEMBRANE FUEL CELLS (PEMFC); THERMAL EFFECTS;

EQUILIBRIUM STRAIN; POLYMER EXCHANGE MEMBRANE FUEL CELLS; TENSILE CREEP;

VAPOR PRESSURE;

ARTICLE; ELASTICITY; EQUIPMENT; EQUIPMENT DESIGN; EVALUATION; INSTRUMENTATION; LABORATORY DIAGNOSIS; MATERIALS TESTING; MECHANICS; METHODOLOGY; MICROCLIMATE; MICROMANIPULATION; PRESSURE; REPRODUCIBILITY; SENSITIVITY AND SPECIFICITY; TEMPERATURE; TENSILE STRENGTH;

ELASTICITY; ENVIRONMENT, CONTROLLED; EQUIPMENT DESIGN; EQUIPMENT FAILURE ANALYSIS; MATERIALS TESTING; MECHANICS; MICROMANIPULATION; PRESSURE; REPRODUCIBILITY OF RESULTS; SENSITIVITY AND SPECIFICITY; SPECIMEN HANDLING; TEMPERATURE; TENSILE STRENGTH;

EID: 36048953087     PISSN: 00346748     EISSN: None     Source Type: Journal    
DOI: 10.1063/1.2794736     Document Type: Article

References (11)

1. Activity is a measure of the concentration, of a component in the liquid or vapor phase relative to the saturated concentration of the pure substance at that temperature. In the vapor phase, activity is defined as the ratio of vapor pressure of the component in the mixture to the vapor pressure of the pure substance at that temperature. Relative humidity, which refers specifically to water vapor, is defined as water activity X 100.
2. Y. Tang, A. M. Karlsson, M. H. Santare, M. Gilbert, S. Cleghom, and W. B. Johnson, Mater. Sci. Eng., A 425, 297 (2006).
3. M. B. Satterfield, P. M. Majsztrik, A. B. Bocarsly, and J. B. Benziger, J. Polym. Sci., Part B: Polym. Phys. 44, 2327 (2006).
4. F. Bauer, S. Denneler, and M. Willert-Porada, J. Polym. Sci., Part B: Polym. Phys. 43, 786 (2005).
5. J. Z. Wang, D. A. Dillard, and T. C. Ward, J. Polym. Sci., Part B: Polym. Phys. 30, 1391 (1992).
6. P. W. Majsztrik and J. B. Benziger, U.S. Provisional Patent No. 07-2379-1 (9 April 2007).
7. Y. M. Haddad, Viscoelasticity of Engineering Materials (Chapman and Hall, London, 1995), pp. 33-35.
8. Temperatures lower than ambient can be achieved by replacing the heater element with a liquid to air heat exchanger. Flowing a cooled liquid from a chiller or using liquid nitrogen will allow access to stable low temperatures. However, controlling relative humidity at low temperatures becomes difficult.
9. S. L. Rosen, Fundamental Principles of Polymeric Materials, 2nd ed., (Wiley, New York, 1993), p. 98.
10. Application of the weight at the start of a creep run must be done slowly enough to avoid a spike in stress (beyond the desired static stress) caused by impact of the weight with, the rod. It must also be done with, sufficient speed to be completed in less than 2 s so that (1) instantaneous elastic response can be separated from the delayed elastic and viscous components and (2) creep strain is occurring under the full static stress equal to the force applied by the entire mass divided by the cross sectional area of the sample. The initial strain rate of the sample under the applied stress dictates the slowest acceptable speed for lowering of the weight. A reasonably wide range of lowering speeds gave repeatable results. Only when initial creep rate was very large (>20% per second) did repeatability become an issue, a point beyond the region of linear response of most materials. We found that lowering the mass by hand gave the most flexibility.
11. C. Yang, S. Srinivasan, A. B. Bocarsly, S. Tulyani, and J. B. Benziger, J. Membr. Sci. 237, 145 (2004).