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Photo discoloration

A photocatalytic activity of the titania-modified parylene film in the photo discoloration of methylene blue has been shown [106]. [Pg.57]

The affect of the iron moiety on the photodegradation of the azo dye containing polymers 7 and 10 was studied. In this study [27] polymers 7 and 10 were dissolved in acetonitrile and exposed to UV radition and observed over time to determine the photo-discolorization. Figure 7.6 displays the discoloration of polymer 7. [Pg.188]

Pandey, K.K. A note on the influence of extractives on the photo-discoloration and photo-degradation of wood. Polym. Degrad. Stab. 87(2), 375-379 (2005)... [Pg.103]

Chang, S.T., Chang, H.T. Inhibition of the photo-discoloration of wood by butyrylation. Holzforschung 55, 255-259 (2001)... [Pg.105]

A number of studies have dealt with the photo-induced discoloration and degradation of polyurethanes based on aromatic diisocyanates such as toluene diisocyanate (TDI - represents a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate isomers) and methylene 4,4-diphenyl diisocyanate (MDI) Cl, 2, 3,... [Pg.117]

This type of degradation can also be referred to as photodegradation or ultraviolet (UV) degradation. It includes photo-oxidation. It produces some of the more familiar signs of degradation of plastics embrittlement, discoloration and loss of transparency. [Pg.30]

Minemura, N., "Control of the Photo-Induced Discoloration of Mechanical Pulp with Polyethylene Glycol", Mokuzai Gakkaishi,1978, 24(8) 587. [Pg.203]

Minemura, N. and Umehara, K., "Control of Photo-Induced Discoloration of Paper With Polyethylene Glycol", Kobunkazai no Kagaku, 1986, 31, 55. [Pg.203]

Journal of Vinyl and Additive Technology 3, No.2, June 1997, p.107-11 REVERSIBLE DISCOLORATION EFFECTS IN THE PHOTO AGEING OF POLY(VINYL CHLORIDE)... [Pg.137]

Natural fibers based on cellulose or protein are more prone to degradation due to humidity and temperature than synthetic organic fibers. Photo-degradation occurs when exposed to light (both visible as well as ultraviolet) which shows up as a discoloration and loss in mechanical properties. Most polymeric fibers (natural or synthetic) swell due to moisture absorption. The swelling is generally more in natural fibers. We discuss this topic again in Chapter 4. [Pg.56]

Due to the need to check for particles, fibers, and possible discoloration in drug solutions transparent and colorless packaging materials are desirable. Hence, uncolored glass and plastic, bottles and bags, are commonly used as primary packaging for parenteral. To attain photo protection without losing VIS controllability, transparent containers or covers are necessary. [Pg.313]

Humans have been reported to be able to ingest 300-500 mg daily for several months without adverse effects. Several hundred crewmen on a US Navy vessel were reported to have developed GI symptoms (acute onset of nausea, vomiting, abdominal cramps, and diarrhea) due to hydroquinone contamination of the water system from automatic photo developing systems. Vision disturbances are among the chronic toxic effects, for example, discoloration, distortion, and opacification of the corneas of workers exposed long-term to low levels. Workers exposed chronically may develop a reddish discoloration of the hair, and brown and orange-brown nail discoloration. Further, workers exposed chronically to hydroquinone may... [Pg.1367]

During photo-oxidation discoloration as well as a decrease of the mechanical properties can be observed, which of these two is most important highly depends on the thickness of the article and its application. To increase the stability of PA66 UVAs as well as HALS can be applied (Fig. 17.11). In the case of PA 6 and 12 the light... [Pg.659]

Poly(vinyl halides) (PVC etc.) and PoIy(vinyl alcohol) (PVA).—A series of papers has appeared concerned with the photo-dehydrochlorination, discoloration, and sensitized photolysis of model compounds of PVC,819 and its copolymers.220 The photolysis of poly(vinyl bromide)221 and a trifluorochloroethylene-vinylidene fluoride copolymer228 has been described. The photo-oxidative destruction of PVA has been reported in a series of papers.223... [Pg.532]

Fig. 4.6. Stink bug damage to soybean pods. Pod discoloration due to fungi and bacteria introduced at the feeding site. Pod in the center is undamaged. (Photo courtesy of R. Lut-trell)... Fig. 4.6. Stink bug damage to soybean pods. Pod discoloration due to fungi and bacteria introduced at the feeding site. Pod in the center is undamaged. (Photo courtesy of R. Lut-trell)...
Photo- chemical Heating Dimensional changes deformation, Erosion Discoloration... [Pg.285]

The discoloration is due to a dehydrochlorination process restilting in the formation of long conjugated polyene sequences in the polymer chain [Eq. (7-10)]. Polyenes can give rise to photo-cross-linking reactions. [Pg.197]

Because Fe(II) salts are generated by the decoordination of the cyclopentadieny-liron moiety, they are the most likely candidates responsible for the discoloration. However, because Fe(III) plays a role in the Photo-Fenton reaction, both Fe(II) and Fe(III) salts were added to the organic analogue polymer solutions. Solutions containing 0.1 mM iron (II) and (III) perchlorate gave similar rates in discoloration (Figure 7.8), indicating that both Fe(II) and Fe(ni) take part in the discoloration. [Pg.191]

In yet other polymers, such as with bisphenol polycarbonates both photodegradation and photo-initiated oxidative reactions take place simultaneously. The direct photoreaction is a Erie s rearrangement reaction, while the oxidative reactions result in chain scission and discoloration of the polymer. The chemical pathways involved in the latter process are not well understood. [Pg.861]

Blending methyl methacrylate-butadiene-styrene copolymer with poly(vinyl chloride) for instance was shown to decelerate the dehydrochlorination (leading to discoloration). The gel content, surface energy, and the spectroscopic characteristics of the blend was altered by the presence of the seccHid polymer [158]. In ethylene-propylene-diene rubber EPDM where the third monomer is ethylene-2-norbomene (NB), the photo-oxidation rate as measured by the accumulation of typical products such as hydroperoxides, varied linearly with the NB content [159]. The same held true for peroxide-crosslinked compounds of the same EPDM except that the linear relationship was found between the relative carbonyl absorbance on photoxidation and the amoiuit of peroxide used to crosslink the material... [Pg.861]

Polycarbonate a) Discoloration Yellowing due to photo-fries and oxidative processes. Yellowing on exposure to solar UV radiation. [15,149-152]... [Pg.864]

See other pages where Photo discoloration is mentioned: [Pg.188]    [Pg.188]    [Pg.188]    [Pg.188]    [Pg.102]    [Pg.299]    [Pg.69]    [Pg.269]    [Pg.129]    [Pg.164]    [Pg.205]    [Pg.56]    [Pg.72]    [Pg.130]    [Pg.277]    [Pg.65]    [Pg.305]    [Pg.280]    [Pg.347]    [Pg.211]    [Pg.258]    [Pg.398]    [Pg.299]    [Pg.2]    [Pg.150]    [Pg.227]    [Pg.88]    [Pg.710]    [Pg.131]    [Pg.96]    [Pg.327]   
See also in sourсe #XX -- [ Pg.188 ]



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Discoloration

Discoloring

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