Degradation mechanism of poly(ether‐urethane) Estane® induced by high‐energy radiation. II. Oxidation effects

Abstract

To predict long‐term polymer behavior during a nuclear waste storage time, radiation effects on a segmented aromatic poly(ether‐urethane) induced by high‐energy radiation under oxygen atmosphere were investigated. To obtain a predictive model of polymer radio‐oxidation during several centuries, the first step consists to elaborate the elementary degradation mechanisms. Thus, electron paramagnetic resonance (EPR), Fourier transform infra‐red spectroscopy (FT‐IR), electrospray ionisation‐mass spectrometry (ESI‐MS), and gas mass spectrometry were carried out to identify radicals, chemical modifications, and gases to reach the radio‐oxidative mechanism at doses inferior than 1000 kGy. Degradation mainly occurs at urethane bonds and in polyether soft segments that produces stable oxidative products as formates, alcohols, carboxylic acids and H2, CO2 and CO gases. Predominant degradation occurred at polyether soft segments and crosslinking is in competition with scission. On the basis of the results, a mechanism of degradation for aromatic poly(ether‐urethane) is proposed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 861–878, 2008

Degradation and stabilization of polyurethane elastomers

“…Polyether SSs are very sensitive to photochemical oxidation. The photodegradation of PEtUs can lead to a complete loss of all of the infrared absorption bands from both the ether groups and the products formed by photooxidation of the ether groups [172], with the final degradation products being low-M substances such as ethylene, formates, and carboxylic acids [172,173].…”

Relationships between molar mass and fracture properties of segmented urethane and amide copolymers modified by chemical degradation

“…• A polyether-based TPU, mainly sensitive to oxidation, which causes a molar mass decrease. 16 It can also undergo hydrolysis in specific environments or with long-term aging. • A polyester-based TPU, for which chain scissions can be induced by hydrolysis or oxidation.…”

“…The consequences of chain scissions on mechanical properties are also assessed. To identify relevant relationships between molar mass and fracture properties, we use three types of segmented copolymers: A polyether‐based TPU, mainly sensitive to oxidation, which causes a molar mass decrease 16 . It can also undergo hydrolysis in specific environments or with long‐term aging. A polyester‐based TPU, for which chain scissions can be induced by hydrolysis or oxidation.…”

Complexing power of hydro-soluble degradation products from γirradiated polyvinylchloride: influence on Eu(OH)3(s) solubility and Eu(III) speciation in neutral to alkaline environment

“…It turned out that the more radio-oxidized the polymer, the higher the oxidation rate of HDPs and the lower their molar mass. When the absorbed dose tends to be very high, the expected HDPs for such a polymer should be low molar mass carboxylic acids, aldehydes and formic acid ester [4]. A very recent work succeeded in characterizing HDPs released from an industrial radio-oxidized poly(ester urethane) [5] hydrolysed in water.…”