This study investigated the molecular structure of the polyhydroxyalkanoate (PHA) produced via a microbiological shake flask experiment utilizing oxidized polypropylene (PP) waste as an additional carbon source. The bacterial strain Cupriavidus necator H16 was selected as it is non-pathogenic, genetically stable, robust, and one of the best known producers of PHA. Making use of PHA oligomers, formed by controlled moderate-temperature degradation induced by carboxylate moieties, by examination of both the parent and fragmentation ions, the ESI-MS/MS analysis revealed the 3-hydroxybutyrate and randomly distributed 3-hydroxyvalerate as well as 3-hydroxyhexanoate repeat units. Thus, the bioconversion of PP solid waste to a value-added product such as PHA tert-polymer was demonstrated.
Novel methacrylate copolymers containing polysiloxane (SiMA) and mixed poly(ethyleneglycol)-perfluorohexyl side chains (MEF) were synthesised and dispersed as surface-active additives in crosslinked PDMS films. The amphiphilic behaviour of the copolymers caused surface reconstruction in water which was characterised by dynamic and static contact angle measurements and angle-resolved X-ray photoelectron spectroscopy (XPS) analysis. The XPS CF2/OCH2 ratio between the hydrophobic fluoroalkyl segments and the hydrophilic oxyethylenic segments was high (15/64) for the copolymer richest in MEF (93 mol%), which also had a high percentage of surface fluorine (∼30%). By contrast, an especially low CF2/OCH2 ratio (0/16) and a low percentage of surface fluorine (∼2%) were identified for the copolymer poorest in MEF (14 mol%). Such large differences in surface chemical composition reflected different antifouling and fouling-release properties against the green macroalga Ulva linza. Generally, the films containing the copolymer with the smallest MEF content were able to resist the settlement of zoospores better than those with a high MEF content and had a superior release of sporelings (young plants)
Four photochromic spiropyran-amylose (ASP) biobased polymers with different spiropyran (SP) grafting density, DS, ASP 10 (DS = 0.12), ASP 40 and ASP 40 PA 60 (DS = 0.40), and ASP 100 (DS = 0.97), are synthesized through azide-alkyne cycloaddition of an alkynyl-functional SP derivative onto C6-azidated-amylose (AN 3 ), where the unconverted azide in ASP 40 PA 60 , ASP 100 , and the AN 3 precursor are quenched by clicking with propargyl alcohol (PA). All ASPs are poorly soluble in trifluoroethanol, ethanol, and water but soluble in dimethyl sulfoxide, N,N-dimethylformamide, and hexafluoroisopropanol irrespective of UV irradiation, switching reversibly the grafted SP into zwitterionic merocyanine (MC). Only ASP 10 and ASP 40 are slightly soluble in the low polarity tetrahydrofuran, with ASP 40 showing a marked photochromism and reduction of solubility on SP→MC switching. The photochromism in solution is preserved in the solid state, although with significant differences between the still relatively fast SP→MC photoisomerization and the much slower thermal retro-isomerization. The dynamics of both processes, evaluated in a thin spin-coated ASP 100 film and a thicker ASP 40 photoswitchable coating on glass and paper, is more clearly affected than in solution by the grafting density. Switching the nearly apolar SP into the zwitterionic MC does not significantly affect wettability of the slightly hydrophobic ASP 40 coating.
Canadian government regulatory and closure commitments for oil sands mines and tailings ponds compel oil sands companies to dewater and reclaim the fluid fine tailings (FFT) in the tailings ponds. As a result, extensive research is underway by several organisations to develop methods to understand the reasons for the slow consolidation of FFT and to design treatment methods for mine closure. The most promising technologies for oil sands tailings dewatering are thickening and centrifugation. In this research, large strain consolidation (LSC) and modified Tempe cell, using axis translation technique with shear strength tests, were conducted on in-line flocculated fluid fine tailings and centrifuged cake tailings samples. These tests determine the treated tailings' consolidation, geotechnical properties, unsaturated characteristics and shear strength. The results of the tests provided several useful engineering functions relating matric suction and effective stress to shear strength, solids contents, and water contents. The modified Tempe cell technique, however, yielded results four times faster than the LSC test technique. The methods and evaluations of the engineering functions are discussed.
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