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Figure from:Physical ageing studies in polyetherimide ULTEM 1000

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Fig. 2. Change of enthalpy for a material quenched from the melt (point A) to the amorphous state (point B). Annealing of the material at T,; generates a decrease in enthalpy, or enth- alpy relaxation (curve B or C), approaching the theoretical equilibrium value h,(T,). Heating of the aged sample pro- motes the recovery of enthalpy at T, (curve C to A). — Figure 2 Change of enthalpy for a material quenched from the melt (point A) to the amorphous state (point B). Annealing of the material at T,; generates a decrease in enthalpy, or enth- alpy relaxation (curve B or C), approaching the theoretical equilibrium value h,(T,). Heating of the aged sample pro- motes the recovery of enthalpy at T, (curve C to A).

Related Figures (7)

Fig. 1. Schematic representation of a structural unit of poly- etherimide ULTEM 1000®.

Fig. 3. Schematic representation of: (a) DSC curves of an aged sample and the corresponding reference (unaged) sample; (b) difference between the DSC signal of aged and unaged samples.

Fig. 4. DSC curves of polyethermide ULTEM 1000® aged at T, = T, — 48°C (T, = 170°C) for different times: ((1) reference, (A) 240 min, (©) 2880 min, (@) 8640 min.

Fig. 5. DSC curves of polyethermide ULTEM 1000® aged at T, = T,, — 18°C (T, = 200°C) for different times: (() reference, (A) 15 min, (<) 60 min, (@) 360 min, ( x ) 5760 min.

Fig. 6. Dependence of the enthalpy relaxation on the ageing time for different ageing temperatures: ©, T, = T, — 8°C (210°C); @, T= T,— 18°C (200°C); , T= T,— 28°C (190°C); A, T, = T,— 38°C (180°C); O, T= T,—48°C (180°C).

Figure 7 shows the change in the a dipolar peak, associated with the glass transition of the material, for the example aged at T, = T, — 18°C (T, = 200°C) for different t, values. This plot shows for each ageing time a shift of the « peak towards higher temperatures, and a significant decrease in maximum current and area as t, increases. This behaviour is similar to that observed for all the other ageing temperatures (data not plotted). Fig. 7. TSDC curves of polyetherimide ULTEM 1000® aged at T, = T, — 18°C (T, = 200°C) for different times: (x) refer- ence, (@) 7min, (©) 60min, (A) 180 min, (C1) 360 min (T, = 200°C, t, = 15min, E, = 6 x 10°Vm~’).

those corresponding to other T, values, show that E, is mainly independent of T, and t,, ranging in all cases between 0:9 + 15% and 1:1+ 15%eV. This behaviour is consistent with the window polarization method, in which only the dipoles that respond to a fixed temperature (T, = 200°C in all our experiments) are activated.

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