The Effect of Ultraviolet Irradiation On Polyurethane Solution and On Solid Polymer

Abstract

The course of photodegradation of polyurethane based on tolylene diisocyanate and polyoxypropylene glycol has been studied. The influence of the physical state of the polymer and of the irradiation dose on the reactions was establ ished.The action of light and oxygen leads to the breaking of N-C and C-O bonds in the urethane group of the polymer, and to formation of aromatic amino, azo and carbonyl containing structures, via hydroperoxides. The oxidation of polymer is associated with the progressive darkening of polymer samples.

Photolysis of bisphenol-based polyurethanes in solution

“…The mechanism for photolysis of polyurethane has been discussed, [1][2][3] and the reaction is believed to occur by either (a) rearrangement by the photo-Fries model or (b) formation of quinone compounds. Scheme 3 shows an analogous photoFries mechanism for the model bisphenol biscarbamates that results in the formation of aniline, para-photo-Fries, and ortho-photo-Fries products.…”

“…As a result, the photodecomposition of aromatic diisocyanatebased polyurethanes has been investigated by several researchers over the past three decades. [1][2][3][4][5][6][7] However, the exact mechanism of photodecomposition is obscure. Using an analogy based on studies of aryl monocarbamate compounds such as ethyl N-phenylcarbamate, 8 -11 it has been implied that MDI-based polyurethanes photodecompose, at least to some extent, by a photo-Fries rearrangement process (Scheme 1).…”

“…Scheme 2 illustrates an alternative mechanism, in which photolysis of MDI-based polyurethane produces quinoid-type compounds. [1][2][3][4][5][6][7] Recently, fluorescence spectroscopy has been used to detect photo-Fries rearrangement products from the photolysis of polymers such as polyurethanes 12 and polycarbonates. [13][14] Hoyle et al 12 reported that photo-Fries products resulting from photolysis of aromatic diisocyanate-based polyurethanes in solution can be identified with this technique.…”

Effect of crystallinity and flexibility on the photodegradation of polyurethanes

“…This, of course, severely limits their use in situations which require even moderate exposure to sunlight. As a consequence, considerable attention has been given over the past two decades to the study of the photodegradation process of aromatic diisocyanate based polyurethanes (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14).…”

Ultraviolet Degradation of Polyester-Based Polyurethane

“…In an earlier study we reported the effect of UV irradiation on PUR based on tolylene diisocyanate and polyoxypropylene glycol (12).…”