Visco-elastic behaviour at the nano-level of a commonly used polymer (PET) is characterised using atomic force microscopy (AFM) at a range of temperatures. The modulus, indentation creep and relaxation time of the PET film (thickness = 100 m) is highly sensitive to temperature over an experimental temperature range of 22¿175 ¿C. The analysis showed a 40-fold increase in the amount of indentation creep on raising the temperature from 22 ¿C to 100 ¿C, with the most rapid rise occurring above the glass-to-rubber transition temperature (Tg = 77.1 ¿C). At higher temperatures, close to the crystallisation temperature (Tc = 134.7 ¿C), the indentation creep reduced to levels similar to those at temperatures below Tg. The calculated relaxation time showed a similar temperature dependence, rising from 0.6 s below Tg to 1.2 s between Tg and Tc and falling back to 0.6 s above Tc. Whereas, the recorded modulus of the thick polymer film decreases above Tg, subsequently increasing near Tc. These visco-elastic parameters are obtained via mechanical modelling of the creep curves and are correlated to the thermal phase changes that occur in PET, as revealed by differential scanning calorimetry (DSC).
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/5493 |
| Date | 2012 June 1920 |
| Creators | Grant, Colin, A., Alfouzan, Abdulrahman, Twigg, Peter C., Coates, Philip D., Gough, Timothy D. |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, published version paper |
| Relation | http://www.sciencedirect.com/science/article/pii/S0968432812001783 |
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