Degradation Monitoring of HDPE Material in CO2-Saturated NaCl Environment through Electrochemical Impedance Spectroscopy Technique

Abstract

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.

Compatibility study of high density polyethylene grade 80 gas pipe with synthetic polyglycol-based brake oil

“…47,50 OIT results for IL and OL are compared in equations ( 8)- (10). Initially (A-R), OL is found to be more resistant to oxidation as indicated by equation (8). After ageing, the same trend is maintained for both IL and OL with respect to A-R specimens.…”

“…Although they give basic information, typical chemical resistance guides are published by polymer manufacturers but they remain less informative on specific interactions between HDPE and hazardous synthetic oily environments. [1][2][3] As a result, semi-crystalline polyethylene pipes and their components are continuously hard-pressed to extreme limits within conditions involving offshore applications, 4 nuclear power plants, 5 automotive oils, 6,7 corrosive seawaters and hydrogen sulfide gases, [8][9][10] fuels and sour gases [9][10][11][12] and even in HDPE confined concrete columns exposed to acidic environments. 13 In literature, chemical resistance of HDPE pipes towards many aggressive environments is not precisely indicated as shown in guides and charts provided by polymer manufacturers.…”

Dynamic Behavior of Thermally Affected Injection-Molded High-Density Polyethylene Parts Modified by Accelerated Electrons

“…Another possibility of testing is the use of spectral analyses, e.g., Fourier Transform Infrared Spectroscopy FTIR, from which the degree of degradation of this material can be detected, both after modification and after temperature loading. The material should withstand long-term exposure to the temperature, for which it was designed, for the duration of its service life and without noticeable degradation or wear [27][28][29][30][31][32].…”