Extensive damage due to saturated seawater and CO2 exposure under high temperature and pressure in high-density polyethylene (HDPE) has been studied by Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Field Emission Scanning Electron Microscope (FESEM), and Electrochemical Impedance Spectroscopy (EIS). The degradation of square-shaped HDPE samples having 1 mm thickness was investigated at 70 bars with 60, 75, and 90 °C separately for three weeks in an autoclave chamber. A clear indication of aging was observed in terms of chain scission by the formation of the methyl group (1262 cm-1), and the appearance of degradation products, including the alcohol and hydroxyl groups. The decline in glass transition temperature (Tg), melting point (Tm), and crystallinity (Xc) result from branching and formation of degradation products in the aged samples. TGA results reveal that the degradation shifts the characteristic temperatures (T5% and T10%) to lower values compared to virgin HDPE. FESEM images show clear surface cracks and rough patches after 3 weeks. The Xc value increased due to chain mobility at higher temperatures (90 °C). The impedance is relatively high 1011 ohms.cm-2 for a virgin sample, but it drops down to 109 and 106 after degradation. Impedance and dielectric loss were correlated, and the significance of dielectric loss was observed at lower frequencies. These characterizations will contribute to more efficient and detailed evaluation criteria for degradation monitoring.
The present work used fractional model of Casson fluid by utilizing a generalized Fourier's Law to construct Caputo Fractional model. A porous medium containing nanofluid flowing in a channel is considered with free convection and electrical conduction. A novel transformation is applied for energy equation and then solved by using integral transforms, combinedly, the Fourier and Laplace transformations. The results are shown in form of Mittag-Leffler function. The influence of physical parameters have been presented in graphs and values in tables are discussed in this work. The results reveal that heat transfer increases with increasing values of the volume fraction of nanoparticles, while the velocity of the nanofluid decreases with the increasing values of volume fraction of these particles.