After around 50 years of development, the key substance known as polyethylene has been extremely influential in a variety of industries. This paper investigates how polyethylene materials have been used in the domains of water, packaging, and medicine to advance contemporary society in order to comprehend the physical and chemical alterations that polyethylene undergoes after being subjected to long-term environmental variables (e.g., temperature, light, pressure, microbiological factors, etc.). For the safe operation of polyethylene materials, it has always been of the utmost importance to evaluate polyethylene’s service life effectively. This paper reviews some of the most common literature journals on the influence of environmental factors on the degradation process of polyethylene materials and describes methods for predicting the lifetime of degradable polyethylene materials using accelerated aging tests. The Arrhenius equation, the Ozawa–Flynn–Wall (OFW) method, the Friedman method, the Coats–Redfern method, the Kissinger method and Kissinger–Akahira–Sunose (KAS) method, Augis and Bennett’s method, and Advanced Isoconversional methods are all discussed, as well as the future development of polyethylene.

For the problem of classification and identification of defects in polyethylene (PE) gas pipelines, this paper firstly performs preliminary screening of the acquired images and acquisition efficiency of defective image acquisition was improved. Images of defective PE gas pipelines were pre-processed. Then, edge detection of the defective images was performed using the improved Sobel algorithm and an adaptive threshold segmentation method was applied to segment the defects in the pipeline images. Finally, the defect images were morphologically processed to obtain binary images. The obtained binary images were applied with VGG16 to complete the training of the defect classifier. The experimental findings show that in the TensorFlow API environment, the test set’s highest accuracy reached 97%, which can achieve the identification of defect types of underground PE gas transmission pipelines.

In recent years, polyethylene (PE) pipes have been widely utilized for urban natural gas transmission. However, as the use of high-density polyethylene (HDPE) pipes increases, their service life and long-term performance assessment have become one of the most significant issues to be addressed. There has been a ton of studies on PE pipe life prediction techniques both domestically and internationally, but very little has been carried out on PE pipe life prediction in actual gas working environments with varying acid and alkaline levels. This experiment accelerates the aging of PE pipes using acid and alkaline corrosion immersion experiments to determine the lifespan of PE pipes. This study aims to investigate the performance changes of HDPE under strong, weak, and neutral corrosion conditions using corrosion solutions with PH values of 1, 5, and 8, to propose the impact of corrosion caused by various acids and alkalies on the HDPE aging life for natural gas, and to develop a mathematical model between the aging life of polyethylene and the PH values of acid and alkali corrosion solutions. The studies involved soaking and corroding HDPE pipes with various acidity and alkalinity chemicals to speed up the aging process, and then the tensile test was used to determine the mechanical characteristics of the aged PE pipes. Based on our findings, the empirical equation between acidity and service life of PE pipes is obtained by the mathematical fitting method, and a life prediction model of buried city gas HDPE pipes is proposed. The actual life of the aged pipes is determined by the relationship between strain-hardening (SH) modulus and aging time. The findings demonstrate that the service life of PE pipes changes with different levels of acidity and alkalinity: 1.872 days, 1060.507 days, and 1128.58 days following corrosive solution-accelerated aging with solution acidities of PH1, PH5, and PH8, respectively. The life prediction method applies to various plastic pipes in comparable environments as well as HDPE city gas pipes that are subject to acid and alkali corrosion forces.

This article presents an improved model for predicting the shielding effectiveness (SE) at arbitrary observation points within a rectangular enclosure, based on the Baum–Liu–Tesche (BLT) equation and the field strength relationship. The SE at the central observation point is initially predicted using the BLT equation. The relationship between the SE at two observation points located along the same section of the rectangular enclosure is derived from waveguide theory. Subsequently, the SE at arbitrary observation points is predicted based on the SE at the central observation point, for other points within the same section. The model accounts for the impact of eccentric apertures and higher order modes on SE by incorporating the aperture position factor, as well as the characteristic impedance and propagation constant of higher order modes. Furthermore, when the system operates under the main mode, the model allows for the use of simulations or experimental data to obtain SE values for known observation points, thereby enabling the direct prediction of SE at other observation points within the same section. This approach minimizes the need for repeated simulations or experiments, saving both time and cost.

High-density polyethylene (HDPE) pipes have gradually become the first choice for gas networks because of their excellent characteristics. As the use of pipes increases, there will unavoidably be a significant amount of waste generated when the pipes cease their operation life, which, if improperly handled, might result in major environmental contamination issues. In this study, the thermal degradation of polyethylene materials is simulated for different pressures (10, 50, 100, and 150 MPa) and temperatures (2300, 2500, 2700, and 2900 K) in the framework of Reactive Force Field (ReaxFF) molecular dynamics simulation. The main gas products, density, energy, and the mean square displacement with temperature and pressure are also calculated. The findings indicate that raising the temperature leads to an increase in the production of gas products, while changing the pressure has an impact on the direction in which the products are generated; the faster the temperature drops, the less dense the air; both temperature and pressure increase impact the system’s energy conversion or distribution mechanism, changing the system’s potential energy as well as its total energy; the rate at which molecules diffuse increases with temperature, and decreases with pressure. The results of this investigation provide a theoretical basis for the development of the pyrolytic treatment of polyethylene waste materials.