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41.
Wax treatment of wood slows photodegradation 总被引:2,自引:0,他引:2
Boštjan LesarMatja? Pavli? Marko Petri?Andrijana Sever Škapin Miha Humar 《Polymer Degradation and Stability》2011,96(7):1271-1278
Waxes and wax emulsions are one of the most important solutions for non-biocidal wood protection. Wax treated wood is designed for outdoor use, therefore it is of considerable importance to elucidate the influence of weathering on the photodegradation processes. It is presumed, that wax treatment will reduce water uptake and thus reduce or slow down photodegradation processes. In order to test this hypothesis, three types of wax emulsions at two different concentrations were vacuum impregnated into Norway spruce wood specimens: an emulsion of montan wax (LGE), an emulsion of polyethylene (WE1) and an emulsion of oxidized polyethylene (WE6) wax. The samples were exposed to artificial accelerated weathering (AAW) for 500 cycles. Before and after AAW colour, the contact angle of water and moisture content were determined. Chemical and morphological changes at exposed surfaces were also investigated with FTIR spectroscopy and SEM. In parallel, the uptake of wax emulsions and water into the axial surfaces of samples was determined with a tensiometer. The moisture content measurements showed that the best hydrophobic effect was achieved with LGE treated wood, where the lowest colour and FTIR changes were observed as well. These results were supported by tensiometer measurements as well. Presented data clearly showed that high loadings of waxes reduce or at least slow down weathering. Among tested waxes, montan wax was found the most effective. 相似文献
42.
43.
The Extragalactic Background Light (EBL) stands for the mean surface brightness of the sky as we would see it from a representative vantage point in the intergalactic space outside of our Milky Way Galaxy. Averaged over the whole 4π solid angle it represents the collective light from all luminous matter radiated throughout the cosmic history. Part of the EBL is resolved into galaxies that, with the increasing detecting power of giant telescopes and sensitive detectors, are seen to deeper and deeper limiting magnitudes. This resolved part is now known to contribute a substantial or even the major part of the EBL. There still remains, however, the challenge of finding out to what extent galaxies too faint or too diffuse to be discerned individually, individual stars or emission by gas outside the galaxies, or – more speculatively – some hitherto unknown light sources such as decaying elementary particles are accounting for the remaining EBL. We review the recent progress that has been made in the measurement of EBL. The current photometric results suggest that there is, beyond the resolved galaxies, an EBL component that cannot be explained by diffuse galaxy halos or intergalactic stars. 相似文献
44.
Xia Jingwen King Alistair W. T. Kilpeläinen Ilkka Aseyev Vladimir 《Cellulose (London, England)》2021,28(17):10921-10938
Cellulose - Cellulose is an historical polymer, for which its processing possibilities have been limited by the absence of a melting point and insolubility in all non-derivatizing molecular... 相似文献
45.
I. Pop T. Petrişor A. Giurgiu A. Néda 《Journal of Physics and Chemistry of Solids》1985,46(9):1077-1081
The present study reports magnetic susceptibility, electrical resistivity and specific heat measurements on α-titanium. The experimental results indicate the existence of an anomaly in the temperature dependence of these parameters. The temperature dependence of the specific heat indicates that the anomaly observed in these parameters is a second order phase transition. The similarity between the temperature dependence of the magnetic susceptibility of α-titanium and of chromium suggests that α-titanium is an itinerant-electron antiferromagnet, such as chromium, with the Néel temperature at 276 ± 4 K. 相似文献
46.
I. Pop D. Dadârlat T. Petrişor A. Giurgiu 《Journal of Physics and Chemistry of Solids》1981,42(10):927-930
Magnetic susceptibility as a function of temperature of binary CrAl alloys containing 0.7,1.07,1.35,1.59, 1.79,1.98, 2.18, 2.84, 3.74 and 4.36 at %A1 is investigated. Aluminium, by alloying, acts on the Néel temperature of pure chromium giving rise to a complicated phase diagram. The bahaviour of the magnetic susceptibility as a function of temperature, in the ordered phase, for the samples containing 1.28, 2.18 and 2.84 at %A1 is found to be temperature independent. In the paramagnetic region, for the samples containing between 1.07 and 2.84 at %A1, it is found a decrease of the magnetic susceptibility as a function of temperature. 相似文献
47.
The acidity constants of 2-acetyl-3-hydroxy-thiophene (III) and 3-acetyl-4-hydroxy-thiophene (IV) and the stability constants of their complexes with some bivalent metal ions have been determined. The stability of the chelates is discussed as a function of the respective bond orders of the α–β and β–β′ bonds of the thiophene ring. 相似文献
48.
Derivatives of pyrimido(1,2-b)indazole and s-triazino(1,2-b)indazole were prepared by several different routes and some transformations are described. 相似文献
49.
Andrej Petrič M. Tišler Branko Stanovnik 《Monatshefte für Chemie / Chemical Monthly》1983,114(5):615-624
Syntheses of isomeric azolopyridopyrimidines are described. As starting material the corresponding pyridopyrimidines were used. It could be established that in many cases a transformation of a functional group with the purpose to form an annelated five-membered ring proceeded with ring opening at the pyrimidine part. Subsequent ring closure with one carbon synthons gave then the desired tricyclic heterocycles. 相似文献
50.
H. R. Petri 《Fresenius' Journal of Analytical Chemistry》1957,157(1):51
Ohne Zusammenfassung 相似文献