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Sustainable Polymers for Additive Manufacturing
Published in Antonio Paesano, Handbook of Sustainable Polymers for Additive Manufacturing, 2022
The durability of plastic products is advantageous for consumers but harmful to the environment, because discarded plastic products take years to degrade under natural conditions, and can survive even hundreds of years as solid waste before they dissolve. In fact, according to the U.S. National Oceanic and Atmospheric Administration, plastic products ended up in the oceans as marine debris can take up to 600 years before they biodegrade (Table 1.13), depending on the polymers of which they are made (NOAA n.d.). Table 1.13 includes non-plastic products serving as a benchmark along with some most common plastic items. The time taken by plastic items before they degrade span from 20 years for PE grocery bags to 600 years for monofilament fishing lines made of PA, PVDF, PET, PE, and the durability of plastic articles is 1,000 to 10,000 times superior to items made of paper and cotton. Switching to plastics buried in land, their degradation time is 500 years for HDPE bottles 5,000 years for PET bottles, PS insulating packaging and PVC pipes, and 10,000 years for HDPE pipes (Chamas et al. 2020).
Infrastructure and the Need for Condition Assessment
Published in Justin Starr, Water and Wastewater Pipeline Assessment Technologies, 2021
HDPE has seen widespread use in the oil and gas and chemical processing industries, as it is inexpensive, lightweight, and fluid tight. HDPE can be joined together in segments using different types of plastic welding (butt welding, electrofusion, etc.) that create joints that are as strong as or stronger than the surrounding material. HDPE pipes have life estimates of 50–100 years, though much depends on the actual service conditions and installation methods used. Downsides of HDPE include the fact that the material is very temperature sensitive – losing strength and expanding as temperature increases. It also cannot be effectively glued, as no adhesives have been found that will maintain a seal as long as the surrounding pipeline. Further, it is subject to ovality, and many localities require extensive mandrel testing prior to acceptance. While cracks are not a common occurrence in HDPE, when they do occur, they tend to rapidly propagate, dramatically increasing the consequence of failure.
Method for installation of marine HDPE pipeline
Published in Noor Amila Wan Abdullah Zawawi, Engineering Challenges for Sustainable Future, 2016
Y.T. Kim, K.S. Park, H.S. Choi, S.Y. Yu, D.K. Kim
In addition, HDPE is also widely used for lining system which is used in pipeline to enhance corrosion resistance as well as to line damaged pipeline. However, polymer liners can fail in service as well. It could be due to buckling collapse induced by external pressure as well as the aging problem. Failure mode due to buckling collapse induced by external pressure is caused by the combined action of two separate factors such as rapid decompression of pipeline and the permeation of oil derived gasses through the liner wall (Rueda et al. 2015). The rapid decompression of pipeline usually happens during service maintenance and inspection shutdowns. Several analytical models were proposed regarding the buckling collapse of pipeline induced by external pressure (Jacobsen 1974, Glock 1997, El-Sawy 2001).
Environmental assessment of construction and renovation of water distribution networks considering uncertainty analysis
Published in Urban Water Journal, 2020
Mohsen Hajibabaei, Sina Hesarkazzazi, Mayara Lima, Florian Gschösser, Robert Sitzenfrei
In WDNs, various factors such as operational (e.g., pressure management and installation conditions), environmental (e.g., temperature and soil moisture), and pipe-intrinsic factors (e.g., diameter and quality of materials) can influence the life span and failure rate of water pipes (Sanjuan-delmás et al. 2014; Barton et al. 2019). Because these factors vary for different cases, few reliable data can be found for the actual life span of water distribution pipe materials. Sanjuan-delmás et al. (2014) assumed a life span of 50 years for assessing the environmental impacts of 200 mm DI pipe with a design pressure of 10 bar. In addition, some studies have considered average life spans of PVC and HDPE to be 25 ± 5 and 40 ± 10 years, respectively (Morera et al. 2016). In this study, based on the information obtained from the TPWWC and pipe producers (TPWWC 2019), average life spans of 25 years, 50 years, and over 50 years were adopted for PVC, HDPE, and DI pipes, respectively.
Preparation and characterization of thermally stable ABS/HDPE blend for fused filament fabrication
Published in Materials and Manufacturing Processes, 2020
Muhammad Harris, Johan Potgieter, Sudip Ray, Richard Archer, Khalid Mahmood Arif
High-density polyethylene (HDPE) is one of the main polymers among the polyolefin family[25]. Recently, a successful 3D printing of HDPE[26] is reported using a styrene ethylene butylene styrene (SEBS) plate as an adhesive to stick the printed layers to the printing bed. However, the low mechanical strength[26] and high thermal degradation of HDPE[27] are the main reasons to explore blend-based alternatives that can provide high strength with good thermal stability. HDPE has been reported to have significant thermal stability during blending with various polymers. Shahrajabian et al.[28] report improved thermal characteristics for high-density polyethylene/recycled polyethylene terephthalate/maleic anhydride polyethylene (HDPE/rPET/MAPE). Lu et al.[29] present the increase in thermal stability in DCS thermograms with an increase of HDPE contents in PLA. Camacho et al.[30] observe the improvement in resistance to thermo-oxidative degradation in a polypropylene/high-density polyethylene (PP/HDPE) blend. Mir et al.[31] report the improved mechanical and thermal properties with HDPE and chitosan. However, these proposed blends have not been analyzed against aging. Furthermore, the mechanical strength does not meet the commercial requirement.
Hypolimnetic oxygenation of water supply reservoirs using bubble plume diffusers
Published in Lake and Reservoir Management, 2019
Mark Mobley, Paul Gantzer, Pam Benskin, Imad Hannoun, Susan McMahon, David Austin, Roger Scharf
The bubble plume diffusers in the water supply reservoirs of this study are based on a linear design originally developed by the Tennessee Valley Authority for hydropower reservoir release improvements (Mobley and Brock 1995, Mobley 1997). The linear diffusers are constructed of high-density polyethylene (HDPE) piping, porous hose, concrete anchors, and stainless steel connecting components. All HDPE connections are joined by a heat fusion procedure, including all anchor and gas piping connections. Flow control orifices along the length of the diffuser are used to provide a uniform bubble pattern along the full length of the porous hose sections. Diffusers are often more than 1000 m long. Pressure requirements for operating the diffuser include hydrostatic pressure of the water depth of the reservoir and the head loss across the flow control orifices and supply pipes. The HDPE working pressure rating is reduced for contact with oxygen gas and for expected ambient temperatures. Anchor tethers are constructed of nylon-coated stainless steel cable. The tether cable lengths can be designed to hold the diffuser at a specific elevation or distance above the bottom. The diffuser lines are deployed and retrieved without need for divers, utilizing a buoyancy pipe to raise and lower the diffuser in the reservoir. The porous hose is manufactured from linear low-density polyethylene and rubber from recycled car tires. The hose has been shown to provide high oxygen transfer efficiency (DeMoyer et al. 2001) and is capable of distributing oxygen in reservoirs for up to 15 yr without excessive degradation or clogging. The diffuser lines require no maintenance during that time unless the porous hose or piping is damaged by boat anchors or other means.