Ageing study of different types of long-term pressure tested PE pipes by IR-microscopy

Deep Learning and Infrared Spectroscopy: Representation Learning with a β-Variational Autoencoder

“…In Figure b, we show the latent traversal for the second-most informative latent dimension (L2). We note that the traversal is dominated by growth in the 1720 cm –1 ketone carbonyl peak absorbance, which is a major thermooxidative degradation product of polyethylene. − The absorbance of this peak increases dramatically as we traverse L2 from positive to negative values with minor spectral changes elsewhere. Notably, we observed a small increase in terminal vinyl absorption at 908 cm –1 .…”

“…In this Letter, we have used a deep learning approach to study the spectroscopic and corresponding chemical changes that occur during the aging of cross-linked polyethylene (PEX-a) pipe that is increasingly being used for domestic and industrial water transport and heating. PEX-a pipes, especially those that have experienced in-service conditions or undergone accelerated aging, are complex heterogeneous systems, in which the IR spectra exhibit contributions from the polyethylene matrix, multiple stabilizing additives, and numerous degradation products. ,,− Variance in the IR spectra can be induced by different aging processes, degradation processes, and chemical reactions that occur simultaneously in the pipe during in-service use and accelerated aging. To better understand these processes and identify distinct spectroscopic and chemical changes, we have trained an artificial neural network β-variational autoencoder (β-VAE) on a diverse data set of ∼25 000 IR spectra of virgin, in-service, cracked, and aged pipes (see Supporting Information for the β-VAE model architecture, training details, and reconstruction quality statistics).…”

An Investigation Into Property Variances Between Outer and Inner Hdpe Pipe Layers

“…For the case of dug out pipes, the reported cases from literature indicate that Xc evolved practically towards a similar level with a difference between outer and inner surface approaching the 12%. The gas pipe kept a high OIT value while the water pipe indicates that it probably underwent some degradation as its OIT dropped to a low level [14].…”

Structure Evolution and Hoop-Reinforcing Mechanism of Bionic-Inspired Off-Axial Glass Fiber-Reinforced High-Density Polyethylene Pipes Fabricated via Rotating Co-extrusion

“…5,6 Based on the continuous innovation of polymerization technology and stronger appreciation of the molecular structure modification, several generations of HDPE pipe materials have emerged including grade PE63, PE80, PE100, and PE125. 2,7 Nevertheless, these resins will inevitably face the stress distribution defect when used as pressure pipes, of which the hoop stress is twice as much as the axial stress. 8,9 This stress characteristic will bring the risk of bamboo-like splitting for conventional extruded pipes due to the axial arrangement (the extruding direction) of molecular chains.…”

“…Playing the role of “artery” in the lifeline of the city, high-density polyethylene (HDPE) pressure pipelines, such as water and gas pipelines, have usually been perceived as one of the important infrastructures in modern civilization owing to their outstanding long-term properties, excellent chemical resistance, and low cost. − For decades, the global population growth and increasing need for drinking water infrastructure have been expanding the demand for HDPE pipes with higher pressure resistance. Synchronously, a series of stricter standards toward higher-performance HDPE pipe resins have been incrementally established or further perfected nowadays. , Based on the continuous innovation of polymerization technology and stronger appreciation of the molecular structure modification, several generations of HDPE pipe materials have emerged including grade PE63, PE80, PE100, and PE125. , Nevertheless, these resins will inevitably face the stress distribution defect when used as pressure pipes, of which the hoop stress is twice as much as the axial stress. , This stress characteristic will bring the risk of bamboo-like splitting for conventional extruded pipes due to the axial arrangement (the extruding direction) of molecular chains. Commonly, reinforcing fiber, such as low-cost glass fiber (GF), is always utilized to improve the fracture strength of polymer products. , But, troubles still exist since the melt flow also arranges fiber fillers axially; thus, the reinforcement effect will only play an effective role in the axial rather than in the hoop direction.…”