The influence of polychromic light on the surface of MDI based polyurethane elastomer

Investigations on the thermal stability of a MDI based polyurethane elastomer

“…The main methods for destruction of polyurethane wastes are pyrolysis and combustion. Two previous papers present structural modifications and properties variation of a polyurethane (PU) with high molecular weight, obtained from MDI, poly(ethyleneadipate) diol (PEA) and 1,4-butanediol (BD), under the action of polychromic light with > 300 nm [10,11]. In this paper we report the thermal degradation behaviour of the same…”

Degradation and stabilization of polyurethane elastomers

“…The photodegradation mechanism of aromatic PUs is generally much more complex than that of aliphatic PUs, and the products obtained are difficult to separate and identify, but it has been more extensively studied [157][158][159][160][161][162][163][164]. Compared to PUs with aliphatic diisocyanates, those with aromatic diisocyanates are more unstable with respect to light [62].…”

“…On the other hand, during irradiation especially with wavelengths > 340 nm, quinone imides can be formed from the phenyl group. The quinoid structures are considered to be responsible for the typical yellow coloration observed during photodegradation of aromatic PUs [157][158][159][160][161][162][163][164], although other factors may also contribute to the yellowing such as the photo-Fries reaction [157,161]. The color change of aromatic PUs can be correlated with photodegradation by a relative increase in the concentration of carbonyl groups [164].…”

“…Photodegradation can also cause surface gloss loss, increased surface roughness, and the appearance of microcracks and/or blisters [163,[199][200][201][202]. These surface changes could be due to embrittlement as a result of increased crosslinking [200,201], and the formation of hydrophilic photoreaction…”

“…Rosu et al[163] studied the influence of polychromatic light (λ > 300 nm) on the surface of a PU based on 4,4′-MDI, PEA diol, and 1,3-BDO as the ChEx. The formation of photo-Fries rearrangement and Norrish Type II reaction products during irradiation was associated with gloss loss, increased surface roughness, and a change in surface wettability (with the contact angle first decreasing and then increasing) (Error!…”