Chemiluminescence investigation of thermo-oxidative degradation of polyethylenes stabilized with fullerenes
TL;DR: In this paper, the stabilization effect of various carbon materials: [C60]fullerene, three adducts with levopimaric acid, two sorts of carbon black and nanocarbon on HDPE, LDPE and LLDPE have been studied by chemiluminescence at 180, 190 and 200 °C.
About: This article is published in Polymer Degradation and Stability.The article was published on 2003-01-01. It has received 24 citations till now. The article focuses on the topics: Carbon black & Linear low-density polyethylene.
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315 citations
TL;DR: Assessment of the total antioxidant capacity of some commercial fruit juices, spectrophotometrically and by the biamperometric method, using the redox couple DPPH· (2,2-diphenyl-1-picrylhydrazyl/DPPH) and Trolox®, in good agreement.
Abstract: The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple DPPH· (2,2-diphenyl-1-picrylhydrazyl)/DPPH (2,2-diphenyl-1-picrylhydrazine). Trolox® was chosen as a standard antioxidant. In the case of the spectrophometric method, the absorbance decrease of the DPPH· solution was followed. For the biamperometric method, the influence of some parameters like the potential diference, ΔE, DPPH· concentration, and Trolox® concentration was investigated. The calibration graph obtained for Trolox® presents linearity between 5 and 30 µM, (y = 0.059 x + 0.0564, where y represents the value of current intensity, expressed as μA and x the value of Trolox® concentration, expressed as μM; r2 = 0.9944). The R.S.D. value for the biamperometric method was 1.29% (n = 10, c = 15 μM Trolox®). In the case of the spectrophotometric method, the calibration graph obtained for Trolox® presents linearity between 0.01 and 0.125 mM (y = -9.5789 x+1.4533, where y represents the value of absorbance and x, the value of Trolox® concentration, expressed as mM; r2 = 0.9963). The R.S.D. value for the spectrophotometric method was 2.05%. Both methods were applied to total antioxidant activity determination in real samples (natural juices and soft drinks) and the results were in good agreement.
138 citations
TL;DR: In this paper, the photo-and thermal-ageing of MDMO-poly[2-methoxy-5-(3′,7′-dimethyl octyloxy)-1,4-phenylenevinylene (PPV) blended with methano-fullerene[6,6]-phenyl C 61 -butyric acid methyl ester ([60] PCBM), a commonly used active layer of organic solar cells, was studied.
123 citations
TL;DR: The results of studying the wide range of properties of polymeric nanocomposites containing small doses of non-covalently bonded fullerene C60 which are of interest for modern technologies are presented in this paper.
Abstract: The results of studying the wide range of properties of polymeric nanocomposites containing small doses of non-covalently bonded fullerene C60 which are of interest for modern technologies are presented. The character of bonds between components of the composites and the possible reasons for improvement of the properties of the nanocomposites in comparison with pure polymers are considered.
55 citations
TL;DR: In this article, the effects of C 60 on the thermal and thermo-oxidative degradation of high density polyethylene (HDPE) composites were studied. And the results of viscoelastic behavior and gel content reveal that C 60 can trap the alkyl radicals and alkyls peroxide radicals to inhibit hydrogen abstraction to suppress the chain scission and preserve the long chain structure.
37 citations
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TL;DR: In this article, the authors proposed a truncated icosahedron, a polygon with 60 vertices and 32 faces, 12 of which are pentagonal and 20 hexagonal.
Abstract: During experiments aimed at understanding the mechanisms by which long-chain carbon molecules are formed in interstellar space and circumstellar shells1, graphite has been vaporized by laser irradiation, producing a remarkably stable cluster consisting of 60 carbon atoms. Concerning the question of what kind of 60-carbon atom structure might give rise to a superstable species, we suggest a truncated icosahedron, a polygon with 60 vertices and 32 faces, 12 of which are pentagonal and 20 hexagonal. This object is commonly encountered as the football shown in Fig. 1. The C60 molecule which results when a carbon atom is placed at each vertex of this structure has all valences satisfied by two single bonds and one double bond, has many resonance structures, and appears to be aromatic. Before 1985, it was generally accepted that elemental carbon exists in two forms, or allotropes: diamond and graphite. Then, Kroto et al. identified the signature of a new, stable form of carbon that consisted of clusters of 60 atoms. They called this third allotrope of carbon 'buckminsterfullerene', and proposed that it consisted of polyhedral molecules in which the atoms were arrayed at the vertices of a truncated icosahedron. In 1990, the synthesis of large quantities of C60 [see Nature 347, 354–358 (1990)] confirmed this hypothesis.
13,394 citations
AT&T1
TL;DR: In this paper, low-temperature studies of potassium-doped C60 both as films and bulk samples, and demonstrate that this material becomes superconducting is demonstrated by microwave, resistivity and Meissner-effect measurements.
Abstract: THE synthesis of macroscopic amounts of C60 and C70 (fullerenes)1 has stimulated a variety of studies on their chemical and physical properties2,3. We recently demonstrated that C60 and C70 become conductive when doped with alkali metals4. Here we describe low-temperature studies of potassium-doped C60 both as films and bulk samples, and demonstrate that this material becomes superconducting. Superconductivity is demonstrated by microwave, resistivity and Meissner-effect measurements. Both polycrystalline powders and thin-film samples were studied. A thin film showed a resistance transition with an onset temperature of 16 K and essentially zero resistance near 5 K. Bulk samples showed a well-defined Meissner effect and magnetic-field-dependent microwave absorption beginning at 18 K. The onset of superconductivity at 18 K is the highest yet observed for a molecular superconductor.
2,459 citations
TL;DR: Overall, the antioxidation abilities of the compounds examined were rationalized in terms of the number of reactive sites, the location of antioxidant in lipid membranes, and the strength of interactions between antioxidants and membranes.
Abstract: C60, vitamin E, and three C60 derivatives (polar 1 and water-soluble C3/D3C60s) were examined for their antioxidant effects on prevention of lipid peroxidation induced by superoxide and hydroxyl radicals The protection effect on lipid peroxidation was found to be in the sequence: C60 ≥ vitamin E > 1 > none, for liposoluble antioxidants, and C3C60 ≫ D3C60 > none, for water-soluble ones Fluorescence quenching of PyCH2COOH (Py = pyrene) by both C3- and D3C60s shows that the Stern−Volmer constant, KSV, is about the same for both quenchers in aqueous solution Upon addition of liposomes, the fluorescence quenching becomes more efficient: 5-fold higher in KSV for C3C60 than for D3C60 When Py(CH2)nCOOH (n = 1, 3, 5, 9, or 15) was incorporated in lipid membranes, the KSVs all were small and nearly equal for D3C60 but were quite large and different for C3C60 with the sequence: n = 1 < 3 < 5 < 9 < 15 The better protection effect of C3C60 on lipid peroxidation than that of D3C60 is attributed to its stronger
269 citations
TL;DR: In this paper, endohedral holmium metallo-metallo-fullerenes have been utilized in a model metallofullerene radiotracer study, and the results have been evaluated for potential applications of lanthanide metallo/metallide derivatives as new diagnostic or therapeutic radiopharmaceuticals.
155 citations