Identification of gamma irradiated polycarbonate-polybutylene terephthalate stiff polymer blend products using HS-GC/MS, FTIR and UV/Vis spectroscopy

In this study, the fragmentation products of Makro-blend stiff polymer due to gamma exposure were identified using Head space (HS), Gas Chromatography, and Mass Spectrometry (HS-GC/MS) techniques and Fourier Transform Infra-Red (FTIR) spectroscopy. As well the electronic transitions due to gamma exposure were examined using UV/Vis spectroscopy. For the un-irradiated and 10 kGy irradiated samples, one product was detected by (HS-GC/MS) method with a clear peak of Dimethoxyethane (MW = 90), which has a peak area percentage of 98.58% and 97.13%, respectively. With increasing gamma doses the number of identified components was increased. At 1200 kGy, ten components were detected: Biethylene (MW = 54), Dimethoxyethane (MW = 90), 1,1-Dimethoxy-2-propanone (MW = 118), 1,1-Dimethoxy-2-propanol (MW = 120), 1,1-Dimethoxycyclopentane (MW = 130), 1,1-Dimethoxyheptane (MW = 160), 1,1-Dimethoxyoctane (MW = 174), Dimethyl terephthalate (MW = 194), 4-(Diethoxymethyl) benzaldehyde (MW = 208), and Terephthalate dihexyl (MW = 334), which have peaks area percentages of 4.22, 2.98, 25.84, 2.2, 10.65, 38.86, 1.57, 5.91, 1.22, and 6.48, respectively. The recorded mass spectrum of each component confirms the molecular ion peak. The FTIR measurements demonstrate the decrease in the detected band intensities following gamma radiation. Accordingly, a chain scission occurs, which causes the carbonate bond to scission, resulting in the creation of a hydroxyl group and the (–H) abstraction from the backbone of the irradiation blend samples. The absorbance edge of the gamma-exposed samples shifted towards a higher wavelength. This pattern shows that the band gap energy is declining. The use of FTIR and HS-GC/MS in mass spectrometry analysis will be useful tools for examining radiation-induced polymeric fragments and advancing our understanding of the process underlying the creation of these fragments in polymers.