Diffusion‐controlled radiochemical oxidation of bisphenol A polysulfone

Abstract

The radiochemical degradation of bisphenol A polysulfone was investigated under a γ -ray dose rate of 24 kGy h −1 up to 30.7 MGy total absorbed dose at 60 • C using gel permeation chromatography, sol-gel analysis, glass transition and rheometry measurements, and oxidation profile measurements by microscopy coupled with Fourier transform infrared analysis in attenuated total reflectance mode. Thin (200 µm) and thick (2 mm) samples were compared. Thin samples undergo mainly chain scissions whereas thick ones undergo mainly crosslinking. The thickness of oxidized layers and, radiochemical yields for chain scissions, crosslinking, oxygen absorption and radical formation were tentatively determined from experimental data in order to determine the influence of oxidative processes on radiochemical ageing and to establish the nature of the crosslinking reactions.

Synthesis and Properties of Polyethylene‐Bound Antioxidants

“…AO2 has a higher thermal stability than its counterpart AO1, suggesting the secondary antioxidant (thioester) structure makes considerable contribution to the thermal ­stability of AO2. According to the proposed stabilizing mechanisms by thioester‐containing antioxidants, the thioester structure in AO2 very likely decomposed (i.e., sacrificed itself to stabilize host polymer) during the degradation process. Thus, AO2 broke up into two or more small parts, which are more volatile at high temperature (Scheme ).…”

Thermal aging kinetic and effects on mechanical behavior of fully recycled composite based on polypropylene/polyethylene blend

“…In order to be able to detect antioxidants, follow their disappearance and carbonyls build up, many analytical methods are proposed in literature such as IR and UV spectrophotometry and differential scanning calorimetry (DSC) under oxygen (OIT) . Coupling the chemical consumption and physical loss of stabilizers and proposing valid kinetic models is a complex and interesting field that's why in recent years many researchers have been attracted to study it …”

New Developments in the Field of Radiochemical Ageing of Aromatic Polymers

“…However, by reexaminating his results using the above equations, his conclusion is questioned. -Richaud (Richaud et al, 2011) proposed a H-crosslinking mechanism at 60°C, basing on the observation that if isopropopylidene groups are generated, the C-CH 2° group is considerably more reactive than aryl one and should react by coupling to give C-CH 2 -CH 2 -C crosslinking bridges corresponding more to a H-crosslinking mechanism. As a conclusion, it seems that elevating the temperature promotes the crosslinking.…”

“…that their surface undergoes an oxidative degradation leading to chain scission meanwhile bulk undergoes an anaerobic radio-ageing generating radicals reacting only by coupling. This effect was quantified by comparing the degradation of thin and thick samples by means of GPC (for molar mass assessment and subsequently chain scission and crosslinking yields assessment) and T g (Richaud et al, 2011). T g decreases for both 2 mm and 200 µm thick samples, but more significantly for thin films (Fig.…”

“…5). Murakami & Kudo, 2007, Richaud et al, 2011, and PEEK (: 24 kGy h -1 , ,,: 60 MGy h -1 for 3 different initial crystalline microstructures) samples irradiated at several temperatures (Vaughan & Stevens, 1995, Richaud, 2010a.…”