The influence of thermolysis time on the absorption spectra of polyvinyl chloride in acetophenone

摘要

The influence of thermolysis time on the absorption spectra of partially thermally dehydrochlorinated polyvinyl chloride in acetophenone solution is studied. Strong increase in the optical density D_λ of the dehydrochlorinated PVC samples is caused by the increasing amount N_(-C=C-) and the length of chains of conjugated double bonds of carbon -C = C-. It is noted that the optical density D_λ first increases linearly with dehydrochlorination time and then reaches saturation. The estimation of amount of double conjugated carbon bonds in 1 ml versus thermolysis time t is given, which varies between N_(-C=C-) = 4·10~(17) - 7.4·10~(18) for t from 40 to 420 minutes. The effective capture cross section of a photon on conjugated double bonds of carbon for dehydrochlorinated PVC solution in acetophenone is estimated, which was about 10~(-17) cm~2. The analysis is done of the absorption curves «red» shift to longer wavelengths with growth of N_(-C=C-) upon increase of thermolysis time. It is noted that the dependence of the optical density on the wavelength in this range is well described by a simple exponential function.