Photodegradative wavelength dependence of thermally resistant organic polymers

Abstract

synopsisThe wavelength dependence of photodegradation of three ,,high temperature" a r e matic polyamide polymers has been very accurately determined by means of a fast grating spectrograph used in conjunction with a high pressure xenon arc. One of these polymers, the poly-(isophthalamide) of 4,4'-bis(p-aminophenyl)-2,2'bithiazoleJ was found to be degraded significantly by visible light, especially that of 4140 A, wavelength. Both the poly-terephthalamide of 1,3-bis(3-aminobenzamido) benzene and Du Pont Nomex, also an aromatic polyamide, were damaged primarily by radiation in the near ultraviolet region. Degradation band maxima for these polymers were observed a t 3700 A and 3600 A, respectively. All three thermally resistant polymers were thus found to be degraded by light of much longer wavelength than that which is harmful to other common polymers.

Accelerated Aging, Photochemical and Thermal Aspects

“…Their activation spectra are particularly interesting because gross physical changes were observed rather than precisely measured chemical changes. (Johnson et al 1969 reported the loss of tensile strength versus wavelength in their study, finding major activity between about 330 to 390 nm.) Renz et al (1974) used a series of sharp cut-off filters and a xenon-arc source (quartz envelope) to investigate the effect of wavelengths between 200 and 360 nm on a variety of coatings.…”

“…Hirt and Searle did this with sunlight in their original studies (Hirt et al 1959). The Japanese have used a similar approach in which the sample is placed in a spectrograph so that the dispersed wavelengths strike across the sample (Shimada and Kabuki 1968b;Johnson et al 1969;Yano and Murayama 1980;Kenjo 1985). In Australia, Holt and Waters (1985) similarly exposed wool to various narrow wavelength regions using a Jasco CRM-FA Spectroirradiator.…”

Improving the photo-stability of high performance aramid fibers by sol-gel treatment

“…However, even though they show favorable thermal properties [7][8][9][10][11][12][13][14], they exhibit very low resistance to sunlight exposure [15][16][17][18][19][20][21]. Accordingly, based on our former research work, a kind of new method was herein put forward to improve the sunlight resistant property of high performance fibers.…”

The influence of pre‐carbonization on the properties of PAN‐based carbon fibers developed by two‐stage continuous carbonization and air oxidation

“…This has been attributed to weak adhesion between the fiber and matrix. For this reason, surface modifications are commonly applied to carbon fibers to increase their reinforcing ability (2)(3)(4)(5)(6)(7)(8)(9). The surface treatments developed use three principal methods: dry oxidation, wet oxidation, and electrolytic oxidation (10).…”