Assignment of Conjugate Double Bond Systems Produced in Heated PVA Film by Absorption and Excitation Spectra

Abstract

Absorption, emission and excitation spectra of heat-treated PVA film have been interpreted as corresponding to mixtures of –(CH=CH)n– and –(CH=CH)n–CO–, which are distinguishable from each other according to whether spectrum is accompanied with fine structures or not. The former shows fine structures and has had n determined to be 2–14 by analysis of peak locations on the basis of linearity for Lewis-Calvin’s plot. For the latter, n has been determined to be 1–7, and Lewis-Calvin’s plot between the wavelength of band maximum and n also shows a good linearity.

Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

“…The formation of the conjugated polyene structures in the thermal degradation of PVC and PVA is mainly via dehydrochlorination [21][22][23][24][25][26][27][28][29][30][31][32] and dehydration [33][34][35] , respectively. The effects of the preirradiation on the conjugated structure formation observed in this work are believed to be related to the radiation-induced structure changes on the polymer chains as well as the generated small molecular products.…”

The natural and accelerated aging of an acrylic artists' medium

“…While the ultraviolet absorption provides only very indistinct evidence of the chromophores which cause the yellow discoloration-the only prominent mid-ultraviolet peak at 280nm may derive not from the discolored polymer but from a non-ionic surfactant containing a benzene ring-the increase of absorption across a broad wavelength region and the evidence of a series of absorption peaks occurring at regular intervals suggest a similarity to the chromophores which are produced in vinyl polymers such as polyvinyl alcohol (PVOH) [17,18] and polyvinyl chloride (PVC) [19]. In these other polymers, discoloration arises from 'polyene' structures, carbon chains containing conjugated double bonds (alternating single and double carboncarbon bonds in sequence along the chain).…”

Correlation between polypropylene microstructure, cold plasma interaction and subsequent luminescent emission

“…Such a shift of the emission spectrum when conjugation increases has been reported. 16,17 In the case of the laboratory-made samples, the shift is not so clear, but it is manifested at least by a broadening of the emission spectrum, especially in the high wavelength range.…”