Abstract
This paper is devoted to the impact of oxygen diffusion on thermal ageing of PA-6,6. Samples were subjected to ageing in air at temperatures ranging from 140°C to 200°C for different times. Depth profiling methods using AFM measurements were developed to characterise the heterogeneity of the thermal and mechanical properties of the oxidised polymer. A comparison of the results obtained with micro-FTIR profiles was performed to correlate the chemical and physical changes induced by oxidation (i.e., from molecular to macroscopic scales). As a result of diffusion-limited oxidation (DLO), it was shown that polymer oxidised much faster at the surface than in the bulk.
Highlights
Introduction[15][16] Beyond chemical changes, oxygen permeation can spatially affect the degradation of polymer materials
Regarding the basic autoxidation scheme, hydroperoxides are the first oxidative products. [6][7] The decomposition of α-amino hydroperoxides leads to the formation of imides, carboxylic acids, amines and aldehydes. [8][10] Changes in the chemical structure can cause a degradation of the macromolecular architecture [11][12] and microstructure [13][14] and a loss of the functional properties. [15][16] Beyond chemical changes, oxygen permeation can spatially affect the degradation of polymer materials. [17][22] When the oxygen consumption rate is higher than the oxygen permeation, oxidation becomes limited by oxygen diffusion (DLO). [23][24] As a result, an oxidation profile across the material thickness develops and is indicative of heterogeneous oxidation
Infrared microspectroscopy was used to investigate the distribution of the chemical changes in the thickness of PA 6,6 plates induced by thermal degradation and determine the influence of temperature on this distribution
Summary
[15][16] Beyond chemical changes, oxygen permeation can spatially affect the degradation of polymer materials. Various experimental techniques are employed to investigate the oxidation heterogeneity in polymers, including infrared microspectroscopy [25][27], chemiluminescence [28][30] and oxygen absorption measurements. [18] These techniques allow for the characterisation of chemical changes induced by oxidation. Recent studies using AFM to characterise the changes in material properties due to ageing have suggested that it can be an efficient tool. [31][35] In this paper, oxidation profiles of PA 6,6 thick samples were determined using different techniques that characterise the material changes from molecular to macroscopic scales. The aim was to determine pertinent degradation probes to validate the multiscale approach protocol
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
