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1.
Polyolefins with controlled environmental degradability 总被引:2,自引:0,他引:2
David M. Wiles 《Polymer Degradation and Stability》2006,91(7):1581-1592
Antioxidants and stabilisers, developed to increase the durability of polyolefins, in combination with prooxidant transition metal complexes provide industrial products with widely variable but controlled lifetimes. The low molar mass oxidation products formed during photo-oxidation and thermal oxidation are biodegradable and oxo-biodegradable polyolefins are now widely used in agricultural applications and in degradable packaging as examples. The scientific basis for the performance of oxo-biodegradable materials is explained with reference to naturally occurring macromolecules. Comparison with hydro-biodegradable materials is made and the need is demonstrated for performance standards to be developed that mimic nature's resource recovery mechanism, that of oxo-biodegradation. 相似文献
2.
Reactions between caesium fluoride, bromine, palladium chloride, triiron dodecacarbonyl, dicobalt octacarbonyl, nickelocene, cyclopentadienylmanganese tricarbonyl or decarborane with, acetylenes containing one highly fluorinated aromatic group are described. The products mainly resembled those obtained from analogous experiments involving diphenylacetylene, although in the case of the PdCl2 reaction no intermediate derivatives could be isolated. 相似文献
3.
Melissa M. Cadelis Hugo Gordon Alex Grey Soeren Geese Daniel R. Mulholland Bevan S. Weir Brent R. Copp Siouxsie Wiles 《Molecules (Basel, Switzerland)》2021,26(11)
Fungi have become an invaluable source of bioactive natural products, with more than 5 million species of fungi spanning the globe. Fractionation of crude extract of Neodidymelliopsis sp., led to the isolation of a novel polyketide, (2Z)-cillifuranone (1) and five previously reported natural products, (2E)-cillifuranone (2), taiwapyrone (3), xylariolide D (4), pachybasin (5), and N-(5-hydroxypentyl)acetamide (6). It was discovered that (2Z)-cillifuranone (1) was particularly sensitive to ambient temperature and light resulting in isomerisation to (2E)-cillifuranone (2). Structure elucidation of all the natural products were conducted by NMR spectroscopic techniques. The antimicrobial activity of 2, 3, and 5 were evaluated against a variety of bacterial and fungal pathogens. A sodium [1-13C] acetate labelling study was conducted on Neodidymelliopsis sp. and confirmed that pachybasin is biosynthesised through the acetate polyketide pathway. 相似文献
4.
Melissa M. Cadelis Soeren Geese Benedict B. Uy Daniel R. Mulholland Shara J. van de Pas Alex Grey Bevan S. Weir Brent R. Copp Siouxsie Wiles 《Molecules (Basel, Switzerland)》2021,26(4)
Antimicrobial bioassay-guided fractionation of the endophytic fungi Neofusicoccum australe led to the isolation of a new unsymmetrical naphthoquinone dimer, neofusnaphthoquinone B (1), along with four known natural products (2–5). Structure elucidation was conducted by nuclear magnetic resonance (NMR) spectroscopic methods, and the antimicrobial activity of all the natural products was investigated, revealing 1 to be moderately active towards methicillin-resistant Staphylococcus aureus (MRSA) with a minimum inhibitory concentration (MIC) of 16 µg/mL. 相似文献
5.
6.
M. Day und D. M. Wiles 《Colloid and polymer science》1976,254(8):774
Ohne Zusammenfassung 相似文献
7.
D. J. Carlsson L. H. Gan D. M. Wiles 《Journal of polymer science. Part A, Polymer chemistry》1978,16(9):2365-2376
A series of isomeric fully aromatic polyamides (aramids) were photodegraded in the presence of oxygen. Films and fibers of these aramids gave carboxylic acids as the major products when measured by infrared spectroscopy and potentiometric titration. These acids probably resulted from the oxygen interception of the radicals generated by photocleavage of the amide bonds. In contrast to results found upon irradiation in the absence of oxygen, carboxylic acid formation was accompanied by a rapid loss in molecular weight, and a decrease in useful mechanical properties. Quantum yields for carboxylic acid formation were ≤5.5 × 10?5 mole/einstein and decreased along the aramid series roughly in agreement with increases in Tg. The photo-Fries rearrangement product was observed in aramid fibers irradiated in air, whereas no rearrangement product was seen in films irradiated in air. 相似文献
8.
Kinetics of charge transfer between metals and polymers was studied using an analytical rolling-sphere tool. The rates of charge transfer were related to the area of contact between contacting surfaces and the tunneling current between them. The derived rate equations accounted for the experimentally observed sigmoidal charging curves. Furthermore, for a model system of steel spheres rolling on modified polystyrene supports, it was shown that the magnitudes of separated charges can be varied by adjusting the polymer's surface properties and/or ambient conditions. 相似文献
9.
This Letter describes dynamic self-assembly in a system of stainless steel spheres ( approximately 1 mm in diameter) rolling on a flat dielectric surface under the influence of an external magnetic field that rotates parallel to the plane of the surface. As the spheres move, they charge triboelectrically. Self-assembly is mediated by two types of electrostatic interactions among these charges: (i) attraction between negatively charged regions of the surface and positively charged spheres and (ii) repulsion between the like-charged spheres. The spheres organize into highly ordered rings as a result of these electrostatic interactions. 相似文献
10.
The first preparation of title compound 1 is accomplished. Its heterocyclic structure was characterized spectroscopically and by X‐ray structure analysis. 相似文献