Formation of paramagnetic products in the thermal and photo degradation of polyurethanes and their effect on the development of degradation processes

Belyakov, V.K.; Берлин, А. А.; Bukin, I.I.; Орлов, В. А.; Tarakanov, O.G.

doi:10.1016/0032-3950(68)90217-7

Cited by 28 publications

(6 citation statements)

References 14 publications

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“…As the photolysis proceeded the intensity of the bands of the urethane group decreased whereas the band at 1730 crri became at the same time stronger. It indicated that the urethane sequences are decreased with irradiation time through the breaking of N-C and C-0 bands [2,3,6,12]. The shift of the carbonyl band is attributed to the formation of some oxidized groups by reactions via hydroperoxides [8,9] .…”

Section: Resultsmentioning

confidence: 99%

“…The photochemical processes in polyurethane based on aromatic diisocyanates include the free radical reactions [2,3,6,7] which are presented on Scheme 1.…”

Section: Introduction He Photodegradation Mechanism Of Polyurethanes mentioning

confidence: 99%

“…Tknown and the products are generally of a very complex nature and difficu It to separate and identify [1][2][3][4][5][6] . The photochemical processes in polyurethane based on aromatic diisocyanates include the free radical reactions [2,3,6,7] which are presented on Scheme 1.…”

Section: Introduction He Photodegradation Mechanism Of Polyurethanes mentioning

confidence: 99%

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

Rek

Bravar

1980

Journal of Elastomers & Plastics

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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.

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Section: Resultsmentioning

confidence: 99%

“…The photochemical processes in polyurethane based on aromatic diisocyanates include the free radical reactions [2,3,6,7] which are presented on Scheme 1.…”

Section: Introduction He Photodegradation Mechanism Of Polyurethanes mentioning

confidence: 99%

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

Rek

Bravar

1980

Journal of Elastomers & Plastics

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“…According to the results obtained and the data taken from the literature (1,10,12,16,26,27) the proposed mechanism scheme for the UV photooxidation can be summarized as follows (Scheme 1): 1. At the beginning of irradiation PUR (1) the reactions which lead to the formation of quinoid structures (11) prevail and they are responsible for the intense yellowing of PUR samples.…”

Section: Resultsmentioning

confidence: 99%

“…The photochemical processes in aromatic PUR include the free radical reactions (1,3,5,7), followed by further chemical transformations which lead to the products having complex structures. The attempts to identify the degradative products were made by these authors, including the reason for the appearance of colour (2,4,8), evaluation of gas products (7,9,11) and decrease of the strength under ultraviolet irradiation (6).…”

Section: Introduction He Oxidative Degradation Of Polyurethane Pur mentioning

confidence: 99%

Ultraviolet Degradation of Polyester-Based Polyurethane

Rek

Bravar

1983

Journal of Elastomers & Plastics

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The structural changes after ageing of polyurethane by UV irradiation has been studied by comparative spectroscopic measurements. The polyurethane was prepared from diphenylmethane-4,4'-diisocyanate, (MDI) and polyester from adipic acid and ethylene glycol. The experimental results show that various oxidized structures are formed in UV degraded samples with simultaneous decomposition of polyurethane. This leads to the formation of new structures such as carbonyl, azo, carbodiimide, quinoid as well as polyene sequences. According to the experimental results and the data taken from the literature, the mechanism of the process was discussed.

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Effects of the o‐aromatic ring in the molecular chain on the properties of polyester polyols

Zhu

Zhang

Feng

et al. 2001

J of Applied Polymer Sci

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A series of liquid polyester polyols from adipic acid (AA), phthalic anhydride (PA), ethylene glycol, propanediol-1,2, and trihydroxymethylpropane, varying in the molar ratio of PA to AA, were prepared. The effects of the o-aromatic ring in the molecular chain, which came from PA, on the viscosity, glass-transition temperature, and thermal degradation temperature of the polyester polyols were studied with viscometry, differential scanning calorimetry, and thermogravimetry. The intrinsic viscosity and glass-transition temperature increased with the concentration of the oaromatic ring increasing. The temperature of the maximum thermal degradation rate for aliphatic polyester polyols was 434.20°C. Two steps of thermal degradation were found when there were o-aromatic rings in the molecular chain. One thermal degradation temperature was 358.36 -360.48°C, and the other was 412.85-427.18°C. Polyester polyols with o-aromatic rings had higher stability at lower temperatures (Ͻ240.00°C). However, aliphatic polyester polyols had higher stability at higher temperatures (300.00 -480.00°C). The activation energy and order of degradation were calculated from thermogravimetric curves.

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Formation of paramagnetic products in the thermal and photo degradation of polyurethanes and their effect on the development of degradation processes

Cited by 28 publications

References 14 publications

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

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

Ultraviolet Degradation of Polyester-Based Polyurethane

Effects of the o‐aromatic ring in the molecular chain on the properties of polyester polyols

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