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J.B. Adeniyi 《European Polymer Journal》1984,20(3):291-299
The mechanisms of thermal and photo-oxidative degradation of unstabilized samples of ABS have been discussed in terms of the known chemistry of the unsaturated isomeric units of PB and the chemical species identified by either i.r. spectroscopy or chemical studies. The reactions which lead to the loss of unsaturation and loss of elastomeric properties of the rubber segment, production of hydroxyl and carbonyl species and the development of cross-linking and colour are extremely complex. High degree of correlation between the outlined chemical transformations and the identifiable reaction products has led to a more definitive and clearer mechanism of degradation of ABS, and by inference, PB and PB-based polyblends. 相似文献
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Thermal- and photo-stabilities of unstabilized acrylonitrile-butadiene-styrene terpolymer, ABS, have been investigated by i.r. spectroscopy. Degradation of ABS samples is initiated by attack on the polybutadiene (PB) component; oxidation products containing hydroxyl and carbonyl groups are produced. The effect of prior thermal processing is to introduce into the polymer hydroperoxides arising from oxidative destruction of PB-unsaturation; these hydroperoxides act as catalysts during subsequent u.v. irradiation. The insolubility of degraded samples of ABS is associated with the formation of cross-linked structures and occurs mainly in the PB segment. It is concluded that the degradation characteristics of ABS are essentially those of the polybutadiene component. 相似文献
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Sherif O. Kolade Josephat U. Izunobi Eric C. Hosten Idris A. Olasupo Adeniyi S. Ogunlaja Oluwole B. Familoni 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(8):810-820
The title compound, 10‐iodo‐1,2‐dihydroisoquinolino[2,1‐b][1,2,4]benzothiadiazine 12,12‐dioxide, C15H11IN2O2S ( 8 ), was synthesized via the metal‐free intramolecular N‐iodosuccinimide (NIS)‐mediated radical oxidative sp3‐C—H aminative cyclization of 2‐(2′‐aminobenzenesulfonyl)‐1,3,4‐trihydroisoquinoline, C15H16N2O2S ( 7 ). The amino adduct 7 was prepared via a two‐step reaction, starting from the condensation of 2‐nitrobenzenesulfonyl chloride ( 4 ) with 1,2,3,4‐tetrahydroisoquinoline ( 5 ), to afford 2‐(2′‐nitrobenzenesulfonyl)‐1,3,4‐trihydroisoquinoline, C15H14N2O4S ( 6 ), in 82% yield. The catalytic hydrogenation of 6 with hydrogen gas, in the presence of 10% palladium‐on‐charcoal catalyst, furnished 7 . Products 6 – 8 were characterized by their melting points, IR and NMR (1H and 13C) spectroscopy, and single‐crystal X‐ray diffraction. The three compounds crystallized in the monoclinic space group, with 7 exhibiting classical intramolecular hydrogen bonds of 2.16 and 2.26 Å. All three crystal structures exhibit centrosymmetric pairs of intermolecular C—H…π(ring) and/or π–π stacking interactions. The docking studies of molecules 6 , 7 and 8 with deoxyribonucleic acid (PDB id: 1ZEW ) revealed minor‐groove binding behaviours without intercalation, with 7 presenting the most favourable global energy of the three molecules. Nonetheless, molecule 8 interacted strongly with the DNA macromolecule, with an attractive van der Waals energy of ?15.53 kcal mol?1. 相似文献
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Otoikhian Kevin Shegun Akhabue Christopher E. Aghogho Mujakperuo Adeniyi Adewale George Ighalo Joshua O. 《Russian Journal of Applied Chemistry》2020,93(12):1976-1988
Russian Journal of Applied Chemistry - The study is focused on modelling and optimizing the process parameters on the production of biodiesel from Jatropha Curcas oil using achantinoidea shell... 相似文献
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Adeniyi Adebayo A. Akintayo Cecilia O. Akintayo Emmanuel T. Conradie Jeanet 《Structural chemistry》2020,31(3):861-875
Structural Chemistry - Natural-based polyols are seen by polyurethane industries as an alternative to the petroleum-based polyols because of increasing challenges due to the oil crisis and global... 相似文献
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Emmanuel Adeniyi Olivia Grounds Zachary Stephens Matthias Zeller Sergiy V. Rosokha 《Molecules (Basel, Switzerland)》2022,27(18)
Similarities and differences of halogen and hydrogen bonding were explored via UV–Vis and 1H NMR measurements, X-ray crystallography and computational analysis of the associations of CHX3 (X=I, Br, Cl) with aromatic (tetramethyl-p-phenylenediamine) and aliphatic (4-diazabicyclo[2,2,2]octane) amines. When the polarization of haloforms was taken into account, the strengths of these complexes followed the same correlation with the electrostatic potentials on the surfaces of the interacting atoms. However, their spectral properties were quite distinct. While the halogen-bonded complexes showed new intense absorption bands in the UV–Vis spectra, the absorptions of their hydrogen-bonded analogues were close to the superposition of the absorption of reactants. Additionally, halogen bonding led to a shift in the NMR signal of haloform protons to lower ppm values compared with the individual haloforms, whereas hydrogen bonding of CHX3 with aliphatic amines resulted in a shift in the opposite direction. The effects of hydrogen bonding with aromatic amines on the NMR spectra of haloforms were ambivalent. Titration of all CHX3 with these nucleophiles produced consistent shifts in their protons’ signals to lower ppm values, whereas calculations of these pairs produced multiple hydrogen-bonded minima with similar structures and energies, but opposite directions of the NMR signals’ shifts. Experimental and computational data were used for the evaluation of formation constants of some halogen- and hydrogen-bonded complexes between haloforms and amines co-existing in solutions. 相似文献
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Alaba Peter Adeniyi Popoola Segun I. Abnisal Faisal Lee Ching Shya Ohunakin Olayinka S. Adetiba Emmanuel Akanle Matthew Boladele Abdul Patah Muhamad Fazly Atayero Aderemi A. A. Wan Daud Wan Mohd Ashri 《Journal of Thermal Analysis and Calorimetry》2020,140(4):1811-1823
Journal of Thermal Analysis and Calorimetry - This study explored the predictive modelling of the pyrolysis of rice husk to determine the thermal degradation mechanism of rice husk. The study can... 相似文献
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Simple Zeros of the Riemann Zeta-Function 总被引:1,自引:0,他引:1
Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26. 相似文献