Positron annihilation lifetime measurements of mechanically fatigued polystyrene samples |
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| Authors: | J Erichsen C Nagel K Günther‐Schade M Renner V Altstädt F Faupel |
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| Institution: | 1. Technische Fakult?t der Christian‐Albrechts‐Universit?t zu Kiel, Lehrstuhl für Materialverbunde, Kaiserstrasse 2, D‐24143 Kiel, Germany;2. Universit?t Bayreuth, FAN, Lehrstuhl für Polymere Werkstoffe, Universit?tsstra?e 30, D‐95440 Bayreuth, Germany |
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| Abstract: | Early stages of cyclic fatigue‐loaded polystyrene (PS) specimens were investigated by positron annihilation lifetime spectroscopy (PALS) at a maximum stress amplitude of 15 MPa. PALS yields information about the average unoccupied hole volume. A linear increase in the ortho‐positronium (o‐Ps) lifetime was observed in a range from 0 to 50,000 cycles. This increase occurs homogeneously distributed at different positions along a sample of 170 mm. The average unoccupied void volume increases by 1.2%. On the other hand, the o‐Ps intensity shows no systematic change upon cycling. The results suggest a homogeneous and linear increase in free volume prior to craze formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1991–1995, 2008 |
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| Keywords: | crazing fatigue analysis free volume polystyrene positron annihilation |
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