Ion track etching revisited. V. Etching of aged pristine and swift heavy ion-irradiated polyimide foils after treatment in hot ambient

Abstract

In the previous papers of this series, the result of etching of fresh swift heavy ion (SHI)-irradiated polyethylene terephthalate (PET) foils after thermal annealing in various environments was studied to determine the extent to which thermal annealing is able not only to simulate aging of pristine polymer foils, but also SHI-irradiated foils. The etching results of these foils (obtained using breakthrough times of the etchant across the PET foils that were pre-annealed at different temperatures for constant times) did not always follow the predicted Arrhenius behavior, but showed dip-like deviations that were tentatively attributed to both SHI radiation and ambient effects to the glass transition temperature. To determine whether deviations from the simple Arrhenius behavior also occur for other irradiated polymers, we examined the effect of thermal annealing at different temperatures T of aged SHI-irradiated Kapton foils via the etchant breakthrough times across the SHI tracks. Interestingly, there appeared unexpected wide dip-like deviations from straight Arrhenius plots. Comparison of this curve with corresponding ones of aged non-irradiated Kapton foils, by determining the etchant breakthrough times across the foils, enabled us to assign the obtained high-temperature Arrhenius branch (for T > 80°C) to heal both aged and irradiated polymer foils from aging and/or radiation defects. In contrast, the pristine and irradiated aged samples annealed at lower temperatures follow completely different trends. As in the previous article on PET, we tend to assign the dip-like deviation of the SHI-irradiated Kapton again to the glass transition temperature of this highly radiation-damaged material.

KEYWORDS:

• Polyimide
• ion tracks
• etching
• Arrhenius plot

Acknowledgement

Measurements were mainly carried out in the NPI CAS laboratories of the CANAM infrastructure. D.F. is grateful to the Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, for the guest professorship in the frame of the Cathedra ‘Alonso Fernandez’. We are further obliged to Dr. P. Apel from JINR Dubna, Russia, for providing us with many of the examined ion-irradiated polymer foils.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Crazes are crack-type structures, where both sides are still connected by fibrils.

2 Annealing at temperatures above T_g usually leads to the reduction of the detectability of latent tracks or even to their disappearance (“healing”) (11).

3 The high applied ion energy signifies that the nominal range of the used ions exceeds the foil thickness by far, so that the (essentially electronic) radiation damage along the ion tracks is practically constant.

4 The ambient temperature in the lab was ∼ 20°C; the ambient humidity was ∼70%.

5 Used here: Purux h2o2 (231-765-0) 3% from Schwarzmann GmbH, Germany.

6 Used here: Glycerin E422 (Vol % >99.9%) from Herrlan-PSM, Germany.

7 Used here: Premium Bio-Ethanol (96.6 Vol %) from Pureflame, Germany.

8 Information from the producer (Du Pont).

Additional information

Funding

The project was supported by the Ministry of Education, Youth and Sports of the Czech Republic (Project 3+3, No. 05-6-1118-2014/2023).

Notes on contributors

D. Fink

Prof. Dietmar Fink, expert in materials science, polymer science, nuclear analytical methods, informally in Nuclear Physics Institute of the Czech Academy of Sciences, Rez, CR, and Universidad Autónoma Metropolitana, Mexico City, Mexico.

J. Vacik

Dr. Jiri Vacik, expert in nuclear analytical methods and materials science, group leader, Nuclear Physics Institute of the Czech Academy of Sciences, Rez, CR.

V. Hnatowicz

Prof. Vladimir Hnatowicz, expert in materials science, nuclear analytical methods, atomic spectroscopy, Nuclear Physics Institute of the Czech Academy of Sciences, Rez, CR.

A. Kiv

Prof. Arik Kiv, specialist in materials science, Ben-Gurion University of the Negev, Department of Materials Engineering Israel.