X‐ray photoelectron spectroscopy study on the photodegradation of copolyester model compounds

Abstract

The photodegradation of irradiated PETG and PCCT model compounds namely Tm‐CHDM‐Tm and Tm‐TMCD‐Tm, where Tm refers to the methyl ester of terephthalic acid, CHDM refers to 1, 4‐cyclohexanedimethanol, and TMCD refers to tetramethyl‐1, 3‐cyclobutanediol, was analyzed using X‐ray photoelectron spectroscopy. Photodegradation products were characterized based on high resolution O1s x‐ray photoelectron spectroscopy (XPS) spectra and the spectra of irradiated model compounds showed a decrease in the relative intensity of CO compared to the CO peak. The percentage of CO formation in irradiated model compounds changed in proportion to irradiation time and showed that the model compound containing CHDM was slightly more UV stable than the TMCD based model compound. Photodegradation mechanisms for model compounds were proposed based on XPS spectra. In parallel studies, density functional theory calculations were performed as an approach to predict degradation products, to help interpreting the XPS spectra of model compounds and characterize the reactivity of model compounds.

Jointing of CFRP/5083 Aluminum Alloy by Induction Brazing: Processing, Connecting Mechanism, and Fatigue Performance

“…It is proved that the loose and porous structure of the anodic oxide film is conducive to the formation of robust bonding between CFRP plate and 5083 plate, thus enhancing the mechanical properties of the CFRP/5083 joint. In order to further understand the effect of anodization on the bonding behavior and strength of the CFRP/5083 joint, X-ray photoelectron spectroscopy (XPS) [25,26] was performed on the interface of the CFRP/5083 joint, and the results are shown in Figure 15. Figure 16a is the fitting diagram of O (1 s) peaks at the interface without anodization before induction brazing.…”

“…After the surface of the 5083 aluminum alloy was anodized, the loose and porous structure of the oxide film not only increased the mechanical bonding strength of the interface, but also led to the formation of a new bond at the CFRP/5083 interface, which enhanced the bonding strength of the joint. In order to further understand the effect of anodization on the bonding behavior and strength of the CFRP/5083 joint, X-ray photoelectron spectroscopy (XPS) [25,26] was performed on the interface of the CFRP/5083 joint, and the results are shown in Figure 15. Figure 16a [8,27], it can be inferred that Al-O-C chemical bonds were formed at the interface [27].…”