Bibliografie tematiche / Chemical upcycling of polyethylene

Letteratura scientifica selezionata sul tema "Chemical upcycling of polyethylene"

Autore: Grafiati

Pubblicato: 25 maggio 2024

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Articoli di riviste sul tema "Chemical upcycling of polyethylene":

Xu, Zhen, Nuwayo Eric Munyaneza, Qikun Zhang, Mengqi Sun, Carlos Posada, Paul Venturo, Nicholas A. Rorrer, Joel Miscall, Bobby G. Sumpter e Guoliang Liu. "Chemical upcycling of polyethylene, polypropylene, and mixtures to high-value surfactants". Science 381, n. 6658 (11 agosto 2023): 666–71. http://dx.doi.org/10.1126/science.adh0993.

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Conversion of plastic wastes to fatty acids is an attractive means to supplement the sourcing of these high-value, high-volume chemicals. We report a method for transforming polyethylene (PE) and polypropylene (PP) at ~80% conversion to fatty acids with number-average molar masses of up to ~700 and 670 daltons, respectively. The process is applicable to municipal PE and PP wastes and their mixtures. Temperature-gradient thermolysis is the key to controllably degrading PE and PP into waxes and inhibiting the production of small molecules. The waxes are upcycled to fatty acids by oxidation over manganese stearate and subsequent processing. PP ꞵ-scission produces more olefin wax and yields higher acid-number fatty acids than does PE ꞵ-scission. We further convert the fatty acids to high-value, large–market-volume surfactants. Industrial-scale technoeconomic analysis suggests economic viability without the need for subsidies.

Yang, Weina. "Chemical upcycling of PET: a mini-review of converting PET into value-added molecules". Applied and Computational Engineering 7, n. 1 (21 luglio 2023): 246–50. http://dx.doi.org/10.54254/2755-2721/7/20230462.

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With the increasing consumption of single-use plastics, a large number of petrochemical resources are used as raw materials, and hundreds of thousands of tons of plastic waste are produced every year. Although there are lots of methods that have been developed to solve this issue by recycling plastic waste, none of them can recover the value of the waste in an efficient way that is less economical cost and less harmful to the environment. Polyethylene terephthalate (PET) is one of the most widely produced single-use polymers. It is challenging to recover the value through mechanical recycling due to the degrading of properties during reprocessing. Chemical upcycling/recycling is an alternative to convert the polymer back to the monomer with less environmental effect, which has lower energy demand. Hydrolysis is one of the common methods in chemical upcycling; it can convert PET waste into value-added materials such as H2 fuel. This paper mainly focuses on the method that converts PET to value-added chemicals through hydrolysis in recent years, so as to offer some references for future researches.

Zeng, Manhao, Yu-Hsuan Lee, Garrett Strong, Anne M. LaPointe, Andrew L. Kocen, Zhiqiang Qu, Geoffrey W. Coates, Susannah L. Scott e Mahdi M. Abu-Omar. "Chemical Upcycling of Polyethylene to Value-Added α,ω-Divinyl-Functionalized Oligomers". ACS Sustainable Chemistry & Engineering 9, n. 41 (4 ottobre 2021): 13926–36. http://dx.doi.org/10.1021/acssuschemeng.1c05272.

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Zhang, Fan, Manhao Zeng, Ryan D. Yappert, Jiakai Sun, Yu-Hsuan Lee, Anne M. LaPointe, Baron Peters, Mahdi M. Abu-Omar e Susannah L. Scott. "Polyethylene upcycling to long-chain alkylaromatics by tandem hydrogenolysis/aromatization". Science 370, n. 6515 (22 ottobre 2020): 437–41. http://dx.doi.org/10.1126/science.abc5441.

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The current scale of plastics production and the accompanying waste disposal problems represent a largely untapped opportunity for chemical upcycling. Tandem catalytic conversion by platinum supported on γ-alumina converts various polyethylene grades in high yields (up to 80 weight percent) to low-molecular-weight liquid/wax products, in the absence of added solvent or molecular hydrogen, with little production of light gases. The major components are valuable long-chain alkylaromatics and alkylnaphthenes (average ~C30, dispersity Ð = 1.1). Coupling exothermic hydrogenolysis with endothermic aromatization renders the overall transformation thermodynamically accessible despite the moderate reaction temperature of 280°C. This approach demonstrates how waste polyolefins can be a viable feedstock for the generation of molecular hydrocarbon products.

Aumnate, Chuanchom, Natalie Rudolph e Majid Sarmadi. "Recycling of Polypropylene/Polyethylene Blends: Effect of Chain Structure on the Crystallization Behaviors". Polymers 11, n. 9 (6 settembre 2019): 1456. http://dx.doi.org/10.3390/polym11091456.

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The combination of high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP) is frequently found in polymer waste streams. Because of their similar density, they cannot be easily separated from each other in the recycling stream. Blending of PP/ polyethylenes (PEs) in different ratios possibly eliminate the sorting process used in the regular recycling process. PP has fascinating properties such as excellent processability and chemical resistance. However, insufficient flexibility limits its use for specific applications. Blending of PP with relative flexible PEs might improve its flexibility. This is a unique approach for recycling or upcycling, which aims to maintain or improve the properties of recycled materials. The effects of the branched-chain structures of PEs on the crystallization behavior and the related mechanical properties of such blends were investigated. The overall kinetics of crystallization of PP was significantly influenced by the presence of PEs with different branched-chain structures. The presence of LDPE was found to decrease the overall crystallization rate while the addition of HDPE accelerated the crystallization process of the blends. No negative effect on the mechanical performance and the related crystallinity was observed within the studied parameter range.

Zhang, Xiaoxia, Shaodan Xu, Junhong Tang, Li Fu e Hassan Karimi-Maleh. "Sustainably Recycling and Upcycling of Single-Use Plastic Wastes through Heterogeneous Catalysis". Catalysts 12, n. 8 (26 luglio 2022): 818. http://dx.doi.org/10.3390/catal12080818.

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The huge amount of plastic waste has caused a series of environmental and economic problems. Depolymerization of these wastes and their conversion into desired chemicals have been regarded as a promising route for dealing with these issues, which strongly relies on catalysis for C-C and C-O bond cleavage and selective transformation. Here, we reviewed recent developments in catalysis systems for dealing with single-use plastics, such as polyethylene, polypropylene, and polyethylene glycol terephthalate. The recycling processes of depolymerization into original monomers and conversion into other economic-incentive chemicals were systemically discussed. Rational designs of catalysts for efficient conversion were particularly highlighted. Overall, improving the tolerance of catalysts to impurities in practical plastics, reducing the economic cost during the catalytic depolymerization process, and trying to obtain gaseous hydrogen from plastic wastes are suggested as the developing trends in this field.

Haque, Zenifar G., Jessica Ortega Ramos e Gerardine G. Botte. "(General Student Poster Award Winner - 2nd Place) Electrochemical Routes for Polymer Upcycling". ECS Meeting Abstracts MA2023-01, n. 55 (28 agosto 2023): 2682. http://dx.doi.org/10.1149/ma2023-01552682mtgabs.

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Approximately 380 million tons of plastic are produced annually, and it is projected to rise to nearly 1.1 billion by 2050 [1]. The largest fraction of such waste consists of polyethylene (PE) and polypropylene (PP), which commonly require energy-intensive methods to achieve depolymerization (such as pyrolysis and hydrogenolysis) due to their remarkable thermodynamic stability. Electrochemical methods are a promising alternative for polymer upcycling as they can utilize renewable energy to create an external potential, overcoming the thermodynamic constraints that the C-C bond cleavage endothermicity imposes on low-temperature polymer conversion. They also offer improved chemical process control by manipulating the electrode potential and minimizing the use and storage of hazardous reagents. Electrochemistry provides a broad range of opportunities for establishing green routes to converting plastic into valuable products. Botte's group is investigating electrochemical approaches to convert polyolefins into valuable products like fuels and fatty acids [2]. Our findings indicate that an electrocatalyst in concert with controlled ionic strength and applied potential enable the selective functionalization of polyolefins and their defragmentation towards target molecules regardless of impurities present in the polymer. In this presentation, we will discuss results of the electrochemical functionalization and deconstruction of low-density polyethylene implementing transition metal electrocatalysts. Acknowledgments: The authors would like to acknowledge the financial support of the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Upcycling of Polymers Program, under Award DE-SC0022307 [1] J. E. Rorrer, C. Troyano-Valls, G. T. Beckham, and Y. Román-Leshkov, "Hydrogenolysis of Polypropylene and Mixed Polyolefin Plastic Waste over Ru/C to Produce Liquid Alkanes," ACS Sustainable Chemistry & Engineering, vol. 9, no. 35, pp. 11661-11666, 2021/09/06 2021, doi: 10.1021/acssuschemeng.1c03786. [2] G. G. Botte, "Process for the Electrochemical Up-Cycling of Plastics (US Pending Patent)," U.S. Patent 63040929, 2020.

Alali, Sabah A. S., Meshal K. M. B. J. Aldaihani e Khaled M. Alanezi. "Plant Design for the Conversion of Plastic Waste into Valuable Chemicals (Alkyl Aromatics)". Applied Sciences 13, n. 16 (14 agosto 2023): 9221. http://dx.doi.org/10.3390/app13169221.

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The exponential increase in production and consumption of plastic has led to accumulation of plastic waste in the environment, resulting in detrimental impacts on human health and the natural environment. Plastic pollution not only stems from discarded plastics but also from the chemicals released during plastic production and decomposition. Various waste management strategies exist for plastic waste, including landfilling, recycling, conversion to liquid fuel, and upcycling. Landfilling, which is a prevalent method, contributes to long-term environmental degradation. Recycling is practiced worldwide, but its percentage remains low, particularly in regions like South Asia. Conversion to liquid fuel through pyrolysis has been explored as a viable solution, although commercialization faces challenges. Upcycling, which involves depolymerization and repolymerization, offers an avenue to recycle plastic waste into valuable chemicals, specifically focusing on high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Currently, HDPE and LDPE make up 36% of all plastic trash by mass, but they have the potential to account for far more. When plastic waste is incinerated or buried in the earth, it generates carbon dioxide and heat, which pollute our environment. Depolymerization is a way to chemically recycle plastic waste into monomers, but this process requires a large amount of energy. Controlled partial depolymerization can transform PE into new, high-quality products at a temperature of more than 400 °C with or without a catalyst. In this study, we provide a novel approach for the conversion of plastic waste, particularly HDPE and LDPE, into valuable alkyl aromatics. By implementing controlled partial depolymerization, we propose a plant design capable of transforming plastic waste into high-quality chemicals. The design aims to optimize energy consumption, process efficiency, and product quality. The research findings contribute to sustainable plastic waste management and the reduction in environmental pollution caused by plastic waste.

Otaibi, Ahmed A. Al, Abdulmohsen Khalaf Dhahi Alsukaibi, Md Ataur Rahman, Md Mushtaque e Ashanul Haque. "From Waste to Schiff Base: Upcycling of Aminolysed Poly(ethylene terephthalate) Product". Polymers 14, n. 9 (2 maggio 2022): 1861. http://dx.doi.org/10.3390/polym14091861.

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Recycling plastic waste into valuable materials is one of the contemporary challenges. Every year around 50 million tons of polyethylene terephthalate (PET) bottles are used worldwide. The fact that only a part of this amount is being recycled is putting a burden on the environment. Therefore, a technology that can convert PET-based waste materials into useful ones is highly needed. In the present work, attempts have been made to convert PET-based waste materials into a precursor for others. We report an aminolysed product (3) obtained by aminolysis reaction of PET (1) with 1,2 diaminopropane (DAP, 2) under solvent and catalytic free conditions. The highest amount of monomeric product was obtained upon heating the mixture of diamine and PET at 130 °C. The resulting aminolysed product was then converted to a Schiff-base (5) in 25% yield. The chemical structure of the synthesized compounds was confirmed using multi-spectroscopic techniques. The results of this study will be a valuable addition to the growing body of work on plastic recycling.

Soong, Ya-Hue Valerie, Margaret J. Sobkowicz e Dongming Xie. "Recent Advances in Biological Recycling of Polyethylene Terephthalate (PET) Plastic Wastes". Bioengineering 9, n. 3 (27 febbraio 2022): 98. http://dx.doi.org/10.3390/bioengineering9030098.

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Polyethylene terephthalate (PET) is one of the most commonly used polyester plastics worldwide but is extremely difficult to be hydrolyzed in a natural environment. PET plastic is an inexpensive, lightweight, and durable material, which can readily be molded into an assortment of products that are used in a broad range of applications. Most PET is used for single-use packaging materials, such as disposable consumer items and packaging. Although PET plastics are a valuable resource in many aspects, the proliferation of plastic products in the last several decades have resulted in a negative environmental footprint. The long-term risk of released PET waste in the environment poses a serious threat to ecosystems, food safety, and even human health in modern society. Recycling is one of the most important actions currently available to reduce these impacts. Current clean-up strategies have attempted to alleviate the adverse impacts of PET pollution but are unable to compete with the increasing quantities of PET waste exposed to the environment. In this review paper, current PET recycling methods to improve life cycle and waste management are discussed, which can be further implemented to reduce plastics pollution and its impacts on health and environment. Compared with conventional mechanical and chemical recycling processes, the biotechnological recycling of PET involves enzymatic degradation of the waste PET and the followed bioconversion of degraded PET monomers into value-added chemicals. This approach creates a circular PET economy by recycling waste PET or upcycling it into more valuable products with minimal environmental footprint.

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Tesi sul tema "Chemical upcycling of polyethylene":

Idris, Adamu Aminu. "Upcycling of polyethylenes by catalysis". Electronic Thesis or Diss., Lyon 1, 2023. https://n2t.net/ark:/47881/m6fx79jm.

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La synthèse d’oligomères/molécules téléchéliques fonctionnels directement à partir de déchets de polyéthylène (PE), bien que très intéressante d'un point de vue environnemental et économique, reste encore aujourd'hui un problème majeur à résoudre. En effet, la forte inertie chimique du polyéthylène (liaisons covalentes C(Sp3) – C(Sp3) & C(Sp3) – H(Sp3) très robustes et difficiles à activer) est un frein important à un recyclage chimique efficace et durable de ce type de matériau. Parmi les différentes méthodes chimiques actuellement disponibles pour le traitement des déchets de polyoléfines, on peut citer la pyrolyse, le craquage thermique et/ou l'hydrocraquage catalytique. Cependant, de telles approches conduisent le plus souvent à des mélanges d'hydrocarbures de manière non sélective, difficilement valorisables. Dans cette thèse, nous cherchons à développer une voie plus intéressante vers la circularité des polyoléfines avec comme objectif le recyclage chimique de polyéthylènes en oligomères α,ω – divinyle ou diacétate. Notre stratégie repose sur un processus en deux étapes via d'abord la création d'alcènes internes réactifs sur le squelette principal du polymère par déshydrogénation catalysée par l'iridium, suivie de la dépolymérisation des polymères insaturés résultants par métathèse catalysée par le ruthénium. Cette approche nous a semblé particulièrement bien adaptée à nos objectifs de développer un procédé économe en énergie pour la dépolymérisation du polyéthylène en oligomères fonctionnalisés de faible poids moléculaire à fort potentiel circulaire de réintégration dans la chaîne de valeur du polyéthylène. Une étude approfondie de l’influence des paramètres réactionnels, nature du catalyseur et grades de différents polyéthylènes a d'abord été entreprise pour les deux réactions. Dans un premier temps, nous avons montré que différents niveaux d'insaturations internes pouvaient être générés sur le squelette du PE en faisant varier le ligand du catalyseur et sa concentration ou les conditions de déshydrogénation sans compromettre ses propriétés structurelles et thermiques. Dans un deuxième temps, la métathèse croisée appliquée à ces polyéthylènes insaturés avec l'éthylène et le cis–1,4–diacétoxy–2–butène comme agents de transfert de chaîne a permis d’obtenir des produits téléchéliques divinyle et diester avec des conversions élevées de 86 % et 91 % respectivement. Les produits finaux à haute valeur ajoutée de ce procédé en deux étapes pourraient être utilisés comme matière première pour la conception de nouveaux polymères recyclés, réduisant ainsi à la fois l'exploitation des ressources fossiles pour la production de polymères et son impact environnemental associé
The synthesis of functional telechelic oligomer/molecule platforms directly from polyethylene (PE) wastes, although very appealing from an environmental and economic point of view, remains today a major problem to tackle. Indeed, the strong C(Sp3) – C(Sp3) & C(Sp3) – H(Sp3) σ-covalent bonds of polyethylenes are undoubtedly not only at the origin of the robustness and chemical inertness of PEs relative to many reagents but also dramatically hamper their chemical recycling. Among the different chemical methods currently available for the treatment of polyolefin wastes, one can cite pyrolysis, thermal cracking, and/or catalytic hydrocracking. However, such approaches most often lead to mixtures of hydrocarbons in a non-selective manner, which are difficult to valorize. In this dissertation thesis, we seek to develop a more valuable route toward polyolefins circularity through polyethylenes upcycling into α,ω–divinyl, or diacetate oligomers. Our strategy involves a two-step process via first the creation of reactive internal alkenes on the main polymer backbone by iridium-catalyzed dehydrogenation followed by depolymerization of the resulting unsaturated polymers using Ru–catalyzed metathesis. A thorough screening of the reaction parameters, nature of the catalyst, and substrate scope was first undertaken for both reactions. We have shown that different levels of internal unsaturation can be generated on the PEs backbone by playing with the catalyst ligand, loading, or conditions of dehydrogenation without compromising its structural and thermal properties Subsequent cross-metathesis of these internally unsaturated polyethylenes with ethylene and cis–1,4–diacetoxy–2–butene as chain transfer agents afforded divinyl and diester telechelic products with 86 % and 91 % conversions (of internal double bonds into functional chain ends) respectively. The high-value-added end-products of this two-step process could be used as feed for the synthesis of recycle-by-design polymers, thereby reducing the exploitation of fossils for polymer production and its associated environmental impact

Chohan, Sukhvinder K. "Environmental degradation of polyethylene-based plastics". Thesis, Aston University, 1996. http://publications.aston.ac.uk/9675/.

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The criteria involved in the degradation of polyethylene-based degradable polymer samples have been investigated, with a view to obtaining a clearer mechanism of photo-biodegradation. The compatibility of degradable polymer samples during materials recycling was also studied. Commercial and laboratory prepared degradable polymer samples were oxidised in different environments and the oxidation products formed were studied using various analytical chromatographic and spectroscopic techniques such as HPLC, FT-IR and NMR. It was found that commercial degradable polymer samples which are based on the ECO systems, degrade predominantly via the Norrish II process, whereas the other degradable systems studied (starch-filled polyethylene systems, transition metal systems, including metal carboxylate based polyethylene systems and the photoantioxidant-activator systems) photodegrade essentially via the Norrish I process. In all cases, the major photoxidation products extracted from the degradable polymer samples were found to be carboxylic acids, although, in the polymer itself a mixture of carbonyl containing products such as esters, lactones, ketones and aldehydes was observed. The study also found that the formation of these hydrophilic carbonyl products causes surface swelling of the polymer, thus making bioerosion possible. It was thus concluded that environmental degradation of LDPE is a two step process, the initiation stage being oxidation of the polymer which gives rise to bioassimilable products, which are consequently bioeroded in the second stage, (the biodegradation step). Recycling of the degradable polymer samples as 10% homogeneous and heterogeneous blends was carried out using a single screw extruder (180°C and 210°C) and an internal mixer (190°C). The study showed that commercial degradable polymer samples may be recycled with a minimal loss in their properties.

Müller, Stefan 1971. "Biodegradation of polyethylene thermolysis residue". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20509.

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The ability of several microorganisms to degrade polyethylene thermolysis residue was investigated. This residue is mainly comprised of n-alkanes and n-1-alkenes ranging in chain length of 15 to 45 carbon units and therefore resembles crude oil. The microorganisms investigated were: Y. lipolytica ATCC 8662, Y. lipolytica ATCC 20460, A. paraffineus ATCC 19558, P. aeruginosa PAO1, P. putida ATCC 12633, R. rhodochrous ATCC 21766 and Rhodococcus sp. ATCC 29671. It was found that all seven microorganisms tested were able to degrade the polyethylene thermolysis residue. Results suggest that R. rhodochrous produced a biosurfactant when growing on the polyethylene thermolysis residue.
It was also found that the acclimation of the microorganism to the substrate was an important factor in the degradation of the residue. Using two different acclimation times, two different strains of R. rhodochrous were selected for in the acclimation step. The two different strains showed very different degradation patterns of the polyethylene thermolysis residue. Strain A showed almost no effect of chain length on the degradation rate of the hydrocarbons while the degradation rate of the hydrocarbons for strain B decreased with increasing chain length. This difference in the degradation pattern was attributed to the varying amounts of enzymes present in each strain. Another factor found to affect the degradation pattern was the liquidity of the polyethylene thermolysis residue.

Tang, Zuojian 1967. "Surface morphology of polyethylene blown films". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31072.

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The properties of blown polyethylene (PE) films depend on various factors, including crystallinity, morphology, and orientation, in addition to chemical composition. It has been shown that the optical properties are strongly influenced by surface morphology. In this project, we use non-contact atomic force microscopy (AFM) and polarized light microscopy (PLM) to visualize surface and bulk morphology. Various techniques, such as surface and line roughness, surface and line fractal dimension, pair-correlation function and nearest neighbor distance distribution function, are employed to quantify the description of morphology and to compare the morphological characteristics of a number of polyolefin films of commercial interest. A comprehensive quantitative analysis of surface topography has been performed. The co-monomer of the PE resins was found to play a significant role in the formation and the orientation of spherulite-like domains. The film cross-section microstructure has been evaluated qualitatively by using both AFM and PLM. However, quantitative analysis of bulk morphology cannot be obtained due to knife effects.

McCaffrey, William Chessleigh. "Thermolysis of polyethylene and polyethylenepolystyrene mixtures". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40397.

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Thermolysis was investigated as a process to convert waste olefin-based polymers into value-added products at a moderate temperature. Virgin, linear low density polyethylene was used for the majority of the experiments. The thermolysis of virgin polystyrene, recycled polyethylene and 3:2 mixtures of polyethylene and polystyrene were also investigated. The final process that was developed employed the reactive distillation of polyolefins under an inert atmosphere and at moderate reaction temperatures, ranging from 375 to 450$ sp circ$C. The major products from thermolysis of polyethylene were a distribution of low-molecular-weight straight chain alkanes and $ alpha$-olefins ranging from C$ sb6$ to C$ sb{25}.$ Overall volatile product yields up to 90% were obtained from the starting polymer. The initial molecular structure of the polyethylene was found to have a large effect on the rate of molecular weight reduction. A significantly enhanced rate of thermolysis was also observed when polyethylene was processed as a mixture with polystyrene. The mechanisms of thermolysis of polyethylene, polystyrene and mixtures of the two polymers were elucidated. Furthermore, the mechanism of dimer production from polystyrene was found to be different than what has been reported previously.

Brues, Michael J. (Michael Jason). "Thermolysis of mixtures of polyethylene and polystyrene". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22642.

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The thermolysis of mixtures of polyethylene and polystyrene was investigated. Overall liquid production for the mixture was above the values predicted from individual polymer reactions. No detrimental effects on the styrene production were evident, as over 50% of the initial polystyrene charge was converted to styrene for polystyrene and for mixtures. There were, however, some differences in the secondary products. No incorporation of one polymer onto another was observed, either in the liquid or the residue.
Different reaction conditions were examined. It was determined that using a single reaction temperature (445$ sp circ$C) was as effective at separating the aromatic and aliphatic products as using two different reaction temperatures.
Polystyrene was found to catalyze the thermolysis of polyethylene. Conventional catalysts (Mordenite and FCC zeolite) affected the overall production and product distributions for mixtures and polyethylene, while only changing the product distribution for polystyrene. Hydrogen in the purge gas only slightly decreased the ratio of 1-alkenes to n-alkanes.
Recycled plastics yielded results similar to virgin polymers, although overall liquid production was decreased (probably due to the additives present in the plastics).

Lageraaen, Paul R. (Paul Robert). "Thermolysis of mixtures of polyethylene and polystyrene". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56791.

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Thermolysis of mixtures of linear low density polyethylene, LLDPE, and polystyrene, PS, was investigated. Mixtures having various polyethylene/polystyrene ratios were reacted in a stirred, batch reactor under a nitrogen atmosphere at moderate temperatures, ranging between 350 and 420$ sp circ$C. The major products collected included a volatile product, which was liquid at room temperature, and a wax-like residue. The liquid products were consistently found to contain over 90 percent styrene and toluene with the yield of styrene decreasing as the percentage of polyethylene in the mixture increased. Two fractions were identified in the residue: a high molecular weight polyethylene fraction and a lower molecular weight polystyrene fraction. A significant increase in the solubility of the residue in organic solvents at room temperature was observed as the polystyrene content was raised. The residue became completely soluble in chloroform at a 60/40 ratio of polyethylene/polystyrene. The effect of temperature on the degradation of a selected mixture was also investigated. At temperatures below 390$ sp circ$C, the volatile/residue ratio was independent of the reaction temperature. Above 390$ sp circ$C, the styrene and total liquid product yields increased with increasing temperature, while the yield of residue decreased.

Feng, Lijun 1966. "Melting and crystallization behavior of linear low-density polyethylene". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86069.

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The melting and crystallization behavior of linear low-density polyethylene (LLDPE) is of great scientific and industrial importance. It depends strongly on polymer molecular structural characteristics and processing conditions, and determines polymer application properties. In this work, we study three different types of LLDPE polymers: metallocene-based LLDPEs (m-LLDPEs), Ziegler-Natta-based LLDPEs (ZN-LLDPEs), and m-LLDPE blends.
A generalized equation is introduced to clarify conceptual definitions of polymer melting temperatures. It incorporates the effects of comonomer volume, crystal length, folding surface free energy and enthalpy of fusion. It is successful in describing the characteristic melting temperatures of various alpha-alkene-ethylene copolymers. The proposed equation is used, along with melting traces obtained by differential scanning calorimetry (DSC), to estimate the crystal size number distributions. Furthermore, the melting temperature characteristics are identified, using crystal size number distributions.
The crystallization behavior of LLDPEs is studied by polarized light microscopy (PLM) and DSC. A modified Hoffman-Lauritzen (MHL) expression is proposed for the linear crystallization kinetics by replacing the equilibrium melting temperature, Tm0, with the melting temperature of the crystal stem with the maximum possible length, TmC,n*. The concept of the effective nucleation induction time is introduced, in order to employ the Avrami equation to analyze the overall crystallization kinetics during the initial crystallization stage.
The MHL analysis suggests the presence of three crystallization regimes: regimes III and II, and a special regime IM. The Avrami exponents are respectively 2, 1.5, and 1 in these regimes. The typical optical morphology of LLDPEs is spherulitic. As the crystallization temperature increases, the morphology changes from spherulites without ring bands, to ring-banded spherulites and sometimes to irregular structure with rough ring bands. These structural characteristics seem to correspond to MHL regimes.
Non-linear spherulitic growth behavior is observed in regimes II and IM. This behavior is explained by the reduction of the concentration of crystallizable ethylene sequences in the melt phase. The MHL expression may be still used to analyze non-linear growth crystallization kinetics by employing a variable TmC,n*.

Williams, Gregory R. (Gregory Richard). "Catalyzed thermal oxidation to recover value from waste polyethylene". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60482.

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Polyethylene was thermally oxidized in the presence of air with cobalt(III) tris-(2,4-pentanedionate) as a catalyst and dicumyl peroxide as an initiator. The optimum temperature for oxygen addition was found to be 150$ sp circ$C. At this temperature, after reaction with 4 wt% catalyst and.4 wt% initiator for three hours, the solid residue was 11.5 mol% oxygen, with a number average molecular weight of 2,500, and there was no overall weight loss. Higher temperatures led to lower oxygen content, equal or higher molecular weight and significant weight loss. Infrared analysis indicated that the ratio of carbonyl to hydroxyl oxygen was a constant.
It was concluded that volatilization became a dominant factor and oxygen containing molecules were lost from the solid. Some of the samples were used as the sole carbon source in fermentations with Yarrowia lipolytica and Arthrobacter paraffineus, but no growth was achieved.

Abdallah, Mohammad Raji AlGhazi. "Role of polymer entanglements in polyethylene oxide induced fines flocculation". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38140.

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Abstract (sommario):

On a papermaking machine, fines and colloids are retained in a paper sheet. The most important particle interactions are among particles having a high weight fraction and a short characteristic interaction time. Most of these interactions follow Langmuir kinetics, in which the flocculation efficiency is one of the important parameters. To enhance retention, many retention aids are available, one of which is neutral polyethylene oxide (PEO) used in combination of a phenolic cofactor (CF).
In this work, a new model was derived in which all possible interactions were considered and assumed to follow Langmuir kinetics. Since fines are the main component in the headbox of mechanical grade furnishes, fines homo- and heteroflocculation with a PEO/CF retention aid were investigated in a circulating flow loop, and found to follow Langmuir kinetics. The small amount of fines deposited on the fibers was attributed to the large detachment rate in turbulent shear. The apparent difference in the deposition time and the half time of flocculation was attributed to difference in efficiency. Fines homoflocculation showed that fines are flocculated (without a retention aid) to various extents depending on shear, and that aggregates of flocs will form when a retention aid is added.
The PEO/CF flocculation efficiency was found to be a function of various parameters, i.e., aging of PEO solution, stirring intensity and time of stirring during dissolution, concentration at storage, shearing and dilution prior to injection. Optimum conditions were found for most parameters, and a critical shear intensity was determined. This PEO behavior was attributed to the extent of entanglements of PEO coils, which can be characterized prior to its addition to the flocculation vessel by a newly developed method. In this method, the pressure drop of a PEO solution passing through a capillary constriction was measured and correlated with its flocculation efficiency. Using the derived correlation, the flocculation efficiency can be estimated, and the relevant parameters can be controlled. Moreover, the salt effect on a PEO/CF system in a pulp was investigated. Salt was found to react with a CF causing a decrease in the flocculation efficiency. The effect of this reaction can be eliminated if PEO is added directly after CF addition.

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Libri sul tema "Chemical upcycling of polyethylene":

Zollo, Tancredi. The Canadian polyethylene industry. Ottawa: Conference Board of Canada, 1985.

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Zollo, Tancredi. The Canadian polyethylene industry. Ottawa: The Conference Board of Canada, 1985.

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Malpass, Dennis B. Introduction to industrial polyethylene: Properties, catalysts, processes. Salem, Mass: Scrivener, 2010.

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Paabo, Maya. A literature review of the chemical nature and toxicity of the decomposition products of polyethylenes. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, 1986.

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M, Visakh P., e María Jose Martínez Morlanes. Polyethylene-based blends, composites and nanocomposities. Hoboken, New Jersey: Wiley, 2015.

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Dietrich, Andrea M. Chemical Permeation/Desorption in New and Chlorine-Aged Polyethylene Pipes. Denver, CO: WATER RESEARCH FOUNDATION, 2010.

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National Institute for Occupational Safety and Health., a cura di. Exxon chemical company, pottsville film plant, polyethylene film department, Mar-lin, Pennsylvania. [Atlanta, Ga.?]: U.S. Dept. of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1994.

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Schroder, L. J. Preparation of polyethylene sacks for collection of precipitation samples for chemical analysis. Lakewood, Colo: U.S. Dept. of the Interior, Geological Survey, 1985.

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Schroder, L. J. Preparation of polyethylene sacks for collection of precipitation samples for chemical analysis. Lakewood, Colo: U.S. Dept. of the Interior, Geological Survey, 1985.

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Schroder, L. J. Preparation of polyethylene sacks for collection of precipitation samples for chemical analysis. Lakewood, Colo: U.S. Dept. of the Interior, Geological Survey, 1985.

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Capitoli di libri sul tema "Chemical upcycling of polyethylene":

Schroeck, Peter, Randy Minton, Theresa Healy e Larry Keefe. "Chemical Blowing Agents for Polyethylene". In Handbook of Industrial Polyethylene and Technology, 909–20. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2017. http://dx.doi.org/10.1002/9781119159797.ch34.

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Luo, Chuan, Shujun Dai, Fengping Ni, Chen Ruan, Haisong Ying e Lifeng Yuan. "Determination of content of recycled polyethylene and polyethylene terephthalate blends". In Advances in Energy, Environment and Chemical Engineering Volume 1, 395–400. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003330165-57.

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Inada, Y., A. Matsushima, M. Hiroto, H. Nishimura e Y. Kodera. "Chemical modification of proteins with polyethylene glycols". In Microbial and Eznymatic Bioproducts, 129–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/bfb0102318.

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Tilger, B., e G. Luft. "Computer Model for Tubular High-Pressure Polyethylene Reactors". In Springer Series in Chemical Physics, 335–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-83224-6_27.

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Kiparissides, Costas, e Harilaos Mavridis. "Mathematical Modelling and Sensitivity Analysis of High Pressure Polyethylene Reactors". In Chemical Reactor Design and Technology, 759–77. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4400-8_21.

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Shilpa, Nitai Basak e Sumer Singh Meena. "Microbial Degradation of Conventional Polyethylene Waste: Current Status and Future Prospective". In Advances in Chemical, Bio and Environmental Engineering, 15–32. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-96554-9_2.

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Casiraghi, Antonella, Francesca Selmin, Paola Minghetti, Francesco Cilurzo e Luisa Montanari. "Nonionic Surfactants: Polyethylene Glycol (PEG) Ethers and Fatty Acid Esters as Penetration Enhancers". In Percutaneous Penetration Enhancers Chemical Methods in Penetration Enhancement, 251–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47039-8_15.

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Rehab-Bekkouche, Souheila, Nadjette Kiass e Kamel Chaoui. "Effects of Aggressive Chemical Environments on Mechanical Behavior of Polyethylene Piping Material". In Damage and Fracture Mechanics, 49–57. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-2669-9_6.

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Tóth, A., I. Bertóti, M. Mohai e T. Ujvári. "Surface Modification of Polyethylene by Nitrogen PIII: Surface Chemical and Nanomechanical Properties". In Materials Science Forum, 255–62. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-426-x.255.

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Buccella, Giacomo, Davide Ceresoli, Andrea Villa, Luca Barbieri e Roberto Malgesini. "On the Triggering of Partial Discharges in Polyethylene: Chemical and Electronic Characterization". In Proceedings of the Sixth International Symposium on Dielectric Materials and Applications (ISyDMA’6), 129–37. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11397-0_11.

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Atti di convegni sul tema "Chemical upcycling of polyethylene":

"Activation of polyethylene granules". In Chemical technology and engineering. Lviv Polytechnic National University, 2021. http://dx.doi.org/10.23939/cte2021.01.143.

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Jeong, Woochang, Chanhee You, Thai Ngan Do, Minseong Park, Hegwon Chung, Jonghwan Oh e Jiyong Kim. "Superstructure optimization framework for upcycling of the plastic wastes in a circular economy". In 15th Mediterranean Congress of Chemical Engineering (MeCCE-15). Grupo Pacífico, 2023. http://dx.doi.org/10.48158/mecce-15.t3-p-12.

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"Polyethylene Packages and Polyethylene Terephthalate Bottles - a Source of Precursors for Chemical Syntheses". In 2023 4th International Scientific Conference "Chemical Technology and Engineering". Lviv Polytechnic National University, 2023. http://dx.doi.org/10.23939/cte2023.229.

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Mvango, Sindisiwe, Nompumelelo Mthimkhulu, Pascaline N. Fru, Lynne A. Pilcher e Mohammed O. Balogun. "Physico-chemical characterization of polyethylene glycol-conjugated betulinic acid". In FRACTURE AND DAMAGE MECHANICS: Theory, Simulation and Experiment. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0028479.

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Haryanto, Dewi Hardiningrum F. e Deni Swantomo. "Modification of polyethylene oxide-polyethylene glycol dimethacrylate hydrogel film by the addition of Jatropha multifida sap for wound dressing application". In THE 11TH REGIONAL CONFERENCE ON CHEMICAL ENGINEERING (RCChE 2018). Author(s), 2019. http://dx.doi.org/10.1063/1.5095039.

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Moravskyi, Volodymyr, Anastasiya Kucherenko, Marta Kuznetsova e Ludmila Dulebova. "The metallized polyethylene granules as the basis for creating of thermal energy storage system". In Chemical technology and engineering. Lviv Polytechnic National University, 2019. http://dx.doi.org/10.23939/cte2019.01.180.

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Pantyukhov, Petr, Tatiana Monakhova, Anatoly Popov e Anna Zykova. "Chemical interaction of polyethylene matrix with vegetable fillers in biocomposites". In VIII INTERNATIONAL CONFERENCE ON “TIMES OF POLYMERS AND COMPOSITES”: From Aerospace to Nanotechnology. Author(s), 2016. http://dx.doi.org/10.1063/1.4949697.

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"Heat Storage System Based on Copper-Coates Granules of Polyethylene". In 2023 4th International Scientific Conference "Chemical Technology and Engineering". Lviv Polytechnic National University, 2023. http://dx.doi.org/10.23939/cte2023.139.

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Ahad, Inam Ul, Ahmar Murtaza, Sithara Sreenilayam, Bogusław Budner, Andrzej Bartnik, Henryk Fiedorowicz, Aqeel-ur-Rehman e Dermot Brabazon. "Chemical surface modification of polyethylene terephthalate (PET) films using extreme ultraviolet". In INTERNATIONAL CONFERENCE ON KEY ENABLING TECHNOLOGIES (KEYTECH 2019). AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5123709.

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Alzuhairi, Mohammed. "Bubble column and CFD simulation for chemical recycling of polyethylene terephthalate". In TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES18. Author(s), 2018. http://dx.doi.org/10.1063/1.5039228.

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Rapporti di organizzazioni sul tema "Chemical upcycling of polyethylene":

Cesar A. Ramirez-Sarmiento, Cesar A. Ramirez-Sarmiento. Efficient biological upcycling of polyethylene terephthalate (PET) into high-value compounds. Experiment, ottobre 2023. http://dx.doi.org/10.18258/57487.

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Callahan, Clare, Emily Larson, Clint Noack e Justin Adder. Upcycling Associated Natural Gas into Liquid Chemical Intermediates. Office of Scientific and Technical Information (OSTI), agosto 2022. http://dx.doi.org/10.2172/1882393.

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Britt, Phillip F., Geoffrey W. Coates, Karen I. Winey, Jeffrey Byers, Eugene Chen, Bryan Coughlin, Christopher Ellison et al. Report of the Basic Energy Sciences Roundtable on Chemical Upcycling of Polymers. Office of Scientific and Technical Information (OSTI), aprile 2019. http://dx.doi.org/10.2172/1616517.

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Veith, E. M. ,. Westinghouse Hanford. LLCE burial container high density polyethylene chemical compatibility. Office of Scientific and Technical Information (OSTI), agosto 1996. http://dx.doi.org/10.2172/657480.

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Shuely, Wendel, Patricia Boone, Juan Cajigas e Michael Sheely. Methodology for Long-Term Permeation Test Periods for HD in High-Density Polyethylene: Universal Munitions Storage Container for the Non-Stockpile Chemical Materiel Program. Fort Belvoir, VA: Defense Technical Information Center, maggio 2016. http://dx.doi.org/10.21236/ad1009746.

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Ruschau. L51887 Compatibility of Repair Coatings Applied to Existing Below Grade Coatings. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), aprile 2002. http://dx.doi.org/10.55274/r0010209.

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Abstract (sommario):

Defects and holidays in mainline coatings necessitate the use of repair coatings for all coated pipelines. This includes both newly coated pipelines just out of the plant as well as existing buried lines in need of small repairs. The repair coating must provide corrosion protection for the steel, lessen the demand on the cathodic protection system, and provide good long-term service. In short, the repair coating must protect the pipe to the same extent as the mainline coating. Two additional requirements for repair coatings are that they adhere not only to the steel but also to the existing mainline coating, and that they be field-applicable under varying ambient conditions. Repair coatings sometimes also have to adhere to non-ideal surfaces, including poorly prepared welds, thermite welds, and flash rusted steel. The compatibility of commercially available repair coatings applied to common mainline pipe coatings was investigated by a laboratory investigation. The mainline coatings investigated were fusion bond epoxy (FBE), coal tar enamel, asphalt enamel, cold-applied polyethylene tape wrap, and extruded polyethylene. Specific combinations ofmainline coatings with different types repair coatings were evaluated for chemical compatibility and adhesion strength in three different scenarios:· As applied to a new pipeline coating, simulating initial repairs made at a coating plant or on a job site prior to installation· As applied to an artificially aged pipeline coating, simulating repairs made to a mainline coating which has been in buried service· After artificially aging a repaired mainline coating, simulating the longer term service of an initial repair made at a coating plant or job site prior to installation.

Ruschau. L51961 Coating Compatibility at Thermite Welds and Keyhole Excavations. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dicembre 2002. http://dx.doi.org/10.55274/r0010247.

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Abstract (sommario):

Patching and repairing high performance pipeline coatings requires a high performance repair material to ensure the integrity of the coating system. The application conditions are not optimized as they are during plant applications, so it is imperative that repair coatings applied to mainline coatings will adhere to all coated surfaces so that resources can be focused on optimizing application methods. Compatibility of repair coatings applied to thermite weld components may be inadequate for optimum field performance. When combined with the limiting factors of keyhole excavations it is important to use coatings which are not only compatible with the thermite welds but also are suitable for the keyhole application procedure. A series of 14 pipeline repair coatings were evaluated for their compatibility with the components of a thermite weld. Chemical compatibility was determined in terms of adhesion with the thermite weld individual components: polyethylene wire insulation, polyvinylchloride wire insulation, copper wire, steel, and copper/aluminum thermite alloy. The same coatings were evaluated for their suitability for application by keyhole excavation procedures. A keyhole excavation was simulated using a scaffold over filled soil boxes (dry soil) containing buried pipe sections, and each of the repair coatings was applied by a commercial keyhole excavation company. The ease of application and general suitability was rated. After backfilling and aging for six months, the samples were removed from the soil boxes and the coatings evaluated.

Landau, Sergei Yan, John W. Walker, Avi Perevolotsky, Eugene D. Ungar, Butch Taylor e Daniel Waldron. Goats for maximal efficacy of brush control. United States Department of Agriculture, marzo 2008. http://dx.doi.org/10.32747/2008.7587731.bard.

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Background. Brush encroachment constitutes a serious problem in both Texas and Israel. We addressed the issue of efficacy of livestock herbivory - in the form of goat browsing - to change the ecological balance to the detriment of the shrub vegetation. Shrub consumption by goats is kept low by plant chemical defenses such as tannins and terpenes. Scientists at TAES and ARO have developed an innovative, cost-effective methodology using fecal Near Infrared Spectrometry to elucidate the dietary percentage of targeted, browse species (terpene-richredberry and blueberry juniper in the US, and tannin-rich Pistacialentiscus in Israel) for a large number of animals. The original research objectives of this project were: 1. to clarify the relative preference of goat breeds and the individual variation of goats within breeds, when consuming targeted brush species; 2. to assess the heritability of browse intake and validate the concept of breeding goat lines that exhibit high preference for chemically defended brush, using juniper as a model; 3. to clarify the relative contributions of genetics and learning on the preference for target species; 4. to identify mechanisms that are associated with greater intake of brush from the two target species; 5. to establish when the target species are the most vulnerable to grazing. (Issue no.5 was addressed only partly.) Major conclusions, solutions, achievements: Both the Israel and US scientists put significant efforts into improving and validating the technique of Fecal NIRS for predicting the botanical composition of goat diets. Israeli scientists validated the use of observational data for calibrating fecal NIRS, while US scientists established that calibrations could be used across animals differing in breed and age but that caution should be used in making comparisons between different sexes. These findings are important because the ability to select goat breeds or individuals within a breed for maximal efficiency of brush control is dependent upon accurate measurement of the botanical composition of the diet. In Israel it was found that Damascus goats consume diets more than twice richer in P. lentiscus than Mamber or Boer goats. In the US no differences were found between Angora and Boer cross goats but significant differences were found between individuals within breeds in juniper dietary percentage. In both countries, intervention strategies were found that further increased the consumption of the chemically defended plant. In Israel feeding polyethylene glycol (PEG, MW 4,000) that forms high-affinity complexes with tannins increased P. lentiscus dietary percentage an average of 7 percentage units. In the US feeding a protein supplement, which enhances rates of P450-catalyzed oxidations and therefore the rate of oxidation of monoterpenes, increased juniper consumption 5 percentage units. However, the effects of these interventions were not as large as breed or individual animal effects. Also, in a wide array of competitive tannin-binding assays in Israel with trypsin, salivary proteins did not bind more tannic acid or quebracho tannin than non-specific bovine serum albumin, parotid saliva did not bind more tannins than mixed saliva, no response of tannin-binding was found to levels of dietary tannins, and the breed effect was of minor importance, if any. These fundings strongly suggest that salivary proteins are not the first line of defense from tannin astringency in goats. In the US relatively low values for heritability and repeatability for juniper consumption were found (13% and 30%, respectively), possibly resulting from sampling error or non-genetic transfer of foraging behavior, i.e., social learning. Both alternatives seem to be true as significant variation between sequential observations were noted on the same animal and cross fostering studies conducted in Israel demonstrated that kids raised by Mamber goats showed lower propensity to consume P. lentiscus than counterparts raised by Damascus goats.

Preparation of polyethylene sacks for collection of precipitation samples for chemical analysis. US Geological Survey, 1985. http://dx.doi.org/10.3133/wri854067.

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Health hazard evaluation report: HETA-92-0297-2396, Exxon Chemical Company, Pottsville Film Plant, Polyethylene Film Department, Mar-Lin, Pennsylvania. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, febbraio 1994. http://dx.doi.org/10.26616/nioshheta9202972396.

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