Search results for "PLASTICS"
showing 10 items of 2724 documents
Effect of high methoxyl pectin on pea protein in aqueous solution and at oil/water interface
2010
International audience; The effect of the addition of high methoxyl pectin on the stability of pea protein isolate emulsions was investigated. Except for low pectin concentrations at acidic pHs where bridging flocculation occurred the addition of pectin improved emulsion stability to pH changes and depletion flocculation induced by maltodextrin addition. The mechanism of pectin induced stability was probed by measuring protein-pectin complex formation in solution, zeta potential of the emulsions droplets and the change in surface viscoelasticity on pectin addition. The phase diagrams of pectin-pea protein isolate in solution and pectin-pea protein-stabilized emulsions were established based…
Catalytic oxidation and reduction of polycyclic aromatic hydrocarbons (PAHs) present as mixtures in hydrothermal media
2012
Author's version of an article in the journal: Polycyclic Aromatic Compounds. Also available from the publisher at: http://dx.doi.org/10.1080/10406638.2012.663451 The reactivity of fluorene, anthracene, and fluoranthene under oxidation and reduction conditions were investigated in this study. This project looks at catalytic and green approaches of converting PAHs to less toxic and/or less stable derivatives that are amenable to further degradation. Hydrothermal reactions have been performed at 300°C with pure H2O and Nafion-SiO2 catalyst for oxidation, and pure H2O, HCOOH, Pd-C, and Nafion-SiO2 catalysts for reductive hydrogenation. Time series has been performed for both the oxidation and …
Dual Enzyme-Responsive Capsules of Hyaluronic Acid-block-Poly(Lactic Acid) for Sensing Bacterial Enzymes.
2015
The synthesis of novel amphiphilic hyaluronic acid (HYA) and poly(lactic acid) (PLA) block copolymers is reported as the key element of a strategy to detect the presence of pathogenic bacterial enzymes. In addition to the formation of defined HYA-block-PLA assemblies, the encapsulation of fluorescent reporter dyes and the selective enzymatic degradation of the capsules by hyaluronidase and proteinase K are studied. The synthesis of the dual enzyme-responsive HYA-b-PLA is carried out by copper-catalyzed Huisgen 1,3-dipolar cycloaddition. The resulting copolymers are assembled in water to form vesicular structures, which are characterized by scanning electron microscopy, transmission electron…
Nano- and microplastic analysis: Focus on their occurrence in freshwater ecosystems and remediation technologies
2019
Plastic pollution is a global problem since 2016 when its production reached 322 million tonnes, excluding fibers. Daily discharges of microplastics (MPs, defined as <5 mm in size) are estimated in the range of 50,000 up to 15 million particles, whereas no information on nanoplastic (NP, <100 nm) release is available yet. Different processes further degraded these materials producing more MPs and NPs. This review attempts to fill the void of information on the state-of-art analysis of MPs and NPs (recently identified as emerging contaminants) and provides a critical overview on modern instrumentation, newly developed workflows, and promising techniques for their characterization (Raman and …
Plastic end-of-life alternatives, with a focus on the agricultural sector
2021
The end of life (EoL) of plastic polymers depends on when they stop being considered a resource and begin to be considered a waste. Even with dynamic management, plastic pollution will increase in the coming decades. Reduction strategies focus on reducing the quantities of materials used in the construction of individual objects for packaging, support for reuse and recycling, incentives for gathering low-value plastics, awareness, and simplification. The agricultural sector, a sector in which the use of plastic is (apparently) not high, needs to combine environmental, social, and above all economic aspects, which can help entrepreneurs in the sector to optimize the recycling process.
Liquid chromatography‐Orbitrap Tribrid high‐resolution mass spectrometry using data dependent‐tandem mass spectrometry with triple stage fragmentatio…
2021
A new, fast, and automatic approach has been applied for the tentative identification of unknown substances released by food contact epoxy resin after performing a migration test with food simulant. This approach combines intelligent data acquisition with AcquireX linked to liquid chromatography-Orbitrap Tribrid high-resolution mass spectrometry using data dependent-tandem mass spectrometry with triple stage fragmentation coupled to Compound Discoverer™ software for automated data processing and compound identification. The identification of the observed features was performed using a set of identification criteria, including exact mass, isotope pattern, tandem mass spectrometry spectra mat…
Determination of dynamic properties of flax fibres reinforced laminate using vibration measurements
2017
International audience; Experimental and numerical methods to identify the linear viscoelastic properties of flax fibre reinforced polymer (FFRP) composite are presented in this study. The method relies on the evolution of storage modulus and loss factor as observed through the frequency response. Free-free symmetrically guided beams were excited in the dynamic range of 10 Hz to 4 kHz with a swept sine excitation focused around their first modes. A fractional derivative Zener model has been identified to predict the complex moduli. A modified ply constitutive law has been then implemented in a classical laminates theory calculation (CLT) routine. Overall, the Zener model fitted the experime…
Correlation of epoxy material properties with the toughening effect of fullerene-like WS2 nanoparticles
2016
Abstract This work deals with the toughening effect of inorganic, fullerene-like WS2 (IF-WS2) nanoparticles (NPs) on epoxy. It has been hypothesized that this toughening effect depends on the epoxy’s cross-link density, its molecular defect fraction or its reference fracture toughness K Ic . Seven different epoxy systems were filled with 0.5% laboratory-made IF-WS2 NPs by mass and investigated in order to analyze which material properties are determining the toughening effect. These NPs were similar to commercially available IF-WS2 NPs, but their agglomerates could not be broken up as successfully and they yielded less toughening effect. The cross-link density of the epoxies measured via dy…
POSS Grafting on Polyethylene and Maleic Anhydride-Grafted Polyethylene by One-Step Reactive Melt Mixing
2018
This study reports the one-step reactive melt mixing preparation of organic-inorganic hybrid based on maleic anhydride-grafted polyethylene and 3-(2-aminoethyl)aminopropyl-heptaisobutyl substituted polyhedral oligomeric silsesquioxane, (NPOSS), as well as on low-density polyethylene and allyl-heptaisobutyl-POSS (1POSS) in dicumyl peroxide presence, which is believed to activate the unsaturation of the reactive functional group of POSS itself. The successful grafting of POSS molecules onto polymeric backbones was probed through rheological and spectroscopic analysis. Grafting of POSS molecules enhances their dispersion in the polymeric matrix as shown by morphological analysis. Moreover, the…
Influence of a density mismatch on TMPTMA shells nonconcentricity
2011
Some laser target designs require low-density organic foam shells to study fusion on the French high-power laser laser mega joule. Low-density trimethylolpropane trimethacrylate foam shells composed of C, H, and O, 2 mm diameter, 100-μm wall thickness, and 250 mg cm−3 density are synthesized by a microencapsulation technique using a droplet generator. These shells have to reach a sphericity higher than 99.9% and a nonconcentricity (NC) lower than 1%. The wall thickness variation is one of the most difficult specifications to meet. An important factor in reducing this defect is the density matching between the three phases of the emulsion at polymerization temperature. The influence of a den…