Absorption spectra of irradiated films of polyvinyl chloride coated with perylene.
The visible and UV spectra γ-irradiated films of polyvinyl chloride doped or coated with perylene were recorded. These films were irradiated either under a vacuum, in N2 O or in NH3. In the case of...
Influence of Polymer Packaging Films on Hyperspectral Imaging Data in the Visible—Near-Infrared (450–950 nm) Wavelength Range
Hyperspectral imaging (HSI) has recently emerged as a useful tool for quality analysis of consumer goods (e.g., food and pharmaceutical products). These products are typically packaged in polymeric film prior to distribution; however, HSI experiments are typically carried out on such samples ex-packaging (either prior to or after removal from packaging). This research examines the effects of polymer packaging films (polyvinyl chloride (PVC) and polyethylene terephthalate (PET)) on spectral and spatial features of HSI data in order to investigate the potential of HSI for quality evaluation of packaged goods. The effects of packaging film were studied for hyperspectral images of samples obtained in the visible–near-infrared (Vis-NIR, i.e., 450–950 nm) wavelength range, which is relevant to many food, agricultural, and pharmaceutical products. The dominant influence of the films tested in this wavelength range could be attributed to light scattering. Relative position of the light source, film, and detector were shown to be highly influential on the scattering effects observed. Detection of features on samples imaged through film was shown to be possible after some data preprocessing. This suggests that quality analysis of products packaged in polymer film is feasible using HSI. These findings would be useful in the development of quality monitoring tools for consumer products post-packaging using HSI.
Radiation-induced trapped charge carriers in organic polymers. A model of thermoelectric current generation.
Trapping and detrapping of radiation-induced charge carriers in polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), and several other polymers were investigated. Thermoelectric currents were generated in the polymers after irradiation by thermally stimulating the release of the trapped charges and subjecting them to a temperature gradient. Heating similarly irradiated samples in the absence of a temperature gradient produced a tenfold reduction in the observed current. The charge carriers were determined to be positive from the polarity of the colder electrode. To observe thermoelectric currents, electrons liberated during irradiation had to be trapped to prevent recombination with trapped positive charges. This trapping is not done by the polymer matrix of PMMA at 25°C but by added impurities. PVC contains a built-in trap in the polymer chain at the C-C1 group. The electron trap in commercial PMMA (Lucite) is benzoyl peroxide or another chemical initiator. Electron traps were also internally generat...