Thermal loss of ultraviolet absorbers from bisphenol A (BPA) polycarbonate

Olson, Daniel R.; Webb, K. K.

doi:10.1021/ma00218a008

Cited by 10 publications

(2 citation statements)

References 4 publications

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“…This can be a problem for low T g materials such as polyolefins, plasticized PVC, and UV-cured coatings. However, the rates of diffusion decrease dramatically at T g and can become vanishingly small when materials are well below T g [25,26]. UVA loss by diffusion during use is inconsequential for most thermally cured coatings and engineering thermoplastics.…”

Section: Effect Of Uva Loss On Materials Lifetimementioning

confidence: 99%

Permanence of UV Absorbers in Plastics and Coatings

Pickett¹

2001

ACS Symposium Series

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Ultraviolet absorbers (UVA's) undergo photo-degradation with quantum yields on the order of 10 -6 even in glassy, unreactive matrices such as poly(methyl methacrylate) (PMMA). The kinetics of UVA loss in a film or coating can be described by the equation: A = log 10 [(1-T 0 )10 (A0-kt) + 1] where A is the absorbance at time t, T 0 is the initial transmission, A 0 is the initial absorbance, and k is a zero order rate constant. The rate constant can be found as the slope of log 10 (10 A -1) plotted vs. exposure. The derivation and implications of these equations and a general review of UVA degradation chemistry are discussed, including the effects of the matrix material, concentration, and hindered amine light stabilizers. The rate of UV absorber loss is of relatively minor consequence when the absorber is used as a bulk additive in a polymer, but is of critical importance in the service lifetime of coatings. The kinetics of photochemical UV absorber loss and use of loss rates in coating lifetime predictions are discussed in detail.

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Section: Effect Of Uva Loss On Materials Lifetimementioning

confidence: 99%

Permanence of UV Absorbers in Plastics and Coatings

Pickett¹

2001

ACS Symposium Series

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“…Therefore, arc exposure (uncorrected).Absorbance spectra of acrylic film containing UVA-3 (sample 3 ) after xenon after xenon arc exposure (uncorrected).Absorbance difference spectra of acrylic film containing UVA-3 (sample3) after xenon arc exposure ( final iteration ) .Corrected absorbance spectra of acrylic film containing UVA-3 (sample 3 ) after xenon arc exposure (final iteration).Absorbance difference spectra of acrylic film containing UVA-3 (sample 3 ) Furthermore, the time variation of Aa(260,t) is not substantial so that Aa( 260,t) = Aa( 260,O).…”

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The permanence of UV absorbers in a rubber‐modified acrylic film by UV/visible spectrophotometry

Bonekamp

Maecker

1994

J of Applied Polymer Sci

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A new analysis technique for UV/visible spectrophotometry is described. This technique is used to accurately determine the retention of several UV absorbers ( UVAs) in a rubbermodified acrylic film during xenon arc accelerated weathering. The effects of reflectance, light scattering, and matrix absorbance are deconvoluted from the total apparent absorbance, resulting in an absorbance spectrum due to the UVA alone. All of the UVAs studied exhibit significant losses upon xenon arc exposure, which has important implications for the longterm durability of polymers that utilize these stabilizers.

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Are microencapsulated antioxidants a feasible technology?

Billingham

Garcia-Trabajo

1995

Angew. Makromol. Chem.

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We consider the possibility of stabilising a polymer by using a low-molecular-weight, mobile and soluble antioxidant, trapped in a small volume fraction of encapsulating material so that it is released into the surrounding polymer to compensate for consumption or loss. Two models are discussed. In the "matrix" model, the additive is dissolved in an encapsulant and its release is controlled entirely by the diffusion coefficient in the encapsulant. In the "balloon" model, the pure additive is surrounded by a wall of encapsulant, through which it permeates into the surrounding polymer. Modelling of the two cases allows the required diffusion or permeation coefficients to be calculated for any chosen loss time. It is found that purely diffusion-controlled loss would require improbably low diffusion coefficients, whereas the required permeabilities for balloon models are accessible. It is difficult to imagine a system for which the temperature coefficient of loss rate would be low enough to allow elevated temperature processing without loss of the additive.

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Thermal loss of ultraviolet absorbers from bisphenol A (BPA) polycarbonate

Cited by 10 publications

References 4 publications

Permanence of UV Absorbers in Plastics and Coatings

Permanence of UV Absorbers in Plastics and Coatings

The permanence of UV absorbers in a rubber‐modified acrylic film by UV/visible spectrophotometry

Are microencapsulated antioxidants a feasible technology?

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