Depth Profiling of Photooxidized Styrene-Isoprene Copolymers by Photoacoustic and Micro-Fourier Transform Infrared Spectroscopy

Gonon, Laetitia; Vasseur, Olivier J.; Gardette, Jean‐Luc

doi:10.1366/0003702991946479

Cited by 20 publications

(10 citation statements)

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“…A spatial heterogeneous distribution of the oxidation photoproducts has been observed for all these systems. By comparing micro-FTIR with PAS-FTIR, Gonon et al 17,24 found good agreement between the two methods in the region from 11 to 22 lm where the analyzed layers overlapped. PAS was found to be more suitable to determine the superficial extent of degradation, whereas the micro-FTIR appeared more adapted to depth profiling the bulk properties.…”

Section: Introductionmentioning

confidence: 99%

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Probing photodegradation beneath the surface: a depth profiling study of UV-degraded polymeric coatings with microchemical imaging and nanoindentation

Michaels

Drzal

et al. 2007

J Coat Technol Res

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Photodegradation of polymer coatings generally involves photooxidation, resulting in the formation of oxidized products, chain scission, and crosslinking. On severe exposure to ultraviolet (UV) light in the presence of air, chemical degradation transforms into substantial changes in the physical and mechanical properties, leading to failures of the coatings. Systematic research by NIST on service life prediction of polymeric coatings indicates that the degradation of polymer coatings starts from the submicrometer degradation-susceptible regions at the surface and then grows in width and depth. Additionally, due to the oxygen diffusion effect and the attenuation of the UV light passing through the polymer, the degradation can be spatially heterogeneous. In this study, the changes with depth of the mechanical and chemical properties of a UV-exposed epoxy/polyurethane system were measured by nanoindentation and Fourier transform infrared spectroscopy (FTIR) microscopy using cross-sectioned specimens. Multilayers of epoxy/polyurethane samples were prepared by a draw-down technique. After curing, samples were exposed to the outdoors in Gaithersburg, MD, for four months. Crosssectioned slices of the exposed and unexposed samples, approximately 500 nm thick as-prepared by microtoming, were used for micro-FTIR imaging. Samples for nanoindentation were prepared by embedding the epoxy/polyurethane multilayers (both exposed and unexposed) in a molding compound, followed by microtoming and polishing the embedded films in the thickness direction. Micro-FTIR images clearly show that, for the outdoor exposed samples, substantial amounts of oxidation products are distributed in the 60 lm deep region from the surface to the epoxy bulk, decreasing in the center of epoxy region and increasing again toward the epoxy/urethane interface. Nanoindentation results also show that the modulus significantly increases in the first 60 lm region after UV degradation, and then decreases gradually with depth until a value slightly higher than the modulus of the undegraded epoxy is reached. The modulus rises again in the region near the epoxy/urethane interface. These similarities in the depth profiles of the properties indicate the linkage between the chemical degradation and the mechanical degradation. The study clearly shows that the spatial distribution of chemical species and mechanical properties is heterogeneous in the thickness direction for polymer coatings after UV degradation. It also demonstrates that cross-sectional analysis using nanoindentation and micro-FTIR imaging techniques is a useful method to characterize the mechanical and chemical depth profiles of polymer coating degradation.

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Section: Introductionmentioning

confidence: 99%

“…Gardette et al [20][21][22][23][24] have used micro-FTIR to study the photodegradation of polymers such as polystyrene, polycarbonates, and epoxy. A spatial heterogeneous distribution of the oxidation photoproducts has been observed for all these systems.…”

Section: Introductionmentioning

confidence: 99%

Probing photodegradation beneath the surface: a depth profiling study of UV-degraded polymeric coatings with microchemical imaging and nanoindentation

Michaels

Drzal

et al. 2007

J Coat Technol Res

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“…Gonon et al (1999Gonon et al ( , 2001 used various scanning speeds to determine depth profi les for photo-oxidized styrene-isoprene copolymers. Because of its surface sensitivity and adjustable probe depth, FT-IR PAS has been especially favoured for studying photodegradation.…”

Section: Further Reading On Fourier Transform Infrared Photoacoustic mentioning

confidence: 99%

Fourier transform infrared photoacoustic spectroscopy of ageing composites * *Note: This manuscript has been authored by Iowa State University of Science and Technology under contract no. DE-AC02-07CH11358 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide licence to publish or reproduce the published form of this manuscript

Jones¹,

McClelland²

2008

Ageing of Composites

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“…Such surface limited degradation has been demonstrated in many ways (100), including density profiling (101), modulus profiling (102), and ftir, using both microscopy and photoacoustic techniques (103). The thickness of the oxidized layer depends on the relative rates of oxygen diffusion and consumption, and theoretical models have been reviewed (104)(105)(106).…”

Section: Degradation Volmentioning

confidence: 99%

Degradation

Billingham¹

2002

Encyclopedia of Polymer Science and Technology

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Depth Profiling of Photooxidized Styrene-Isoprene Copolymers by Photoacoustic and Micro-Fourier Transform Infrared Spectroscopy

Cited by 20 publications

References 19 publications

Probing photodegradation beneath the surface: a depth profiling study of UV-degraded polymeric coatings with microchemical imaging and nanoindentation

Probing photodegradation beneath the surface: a depth profiling study of UV-degraded polymeric coatings with microchemical imaging and nanoindentation

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