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131.
132.
Thermoxidative Decomposition of Some Polysulfones under Dynamic Conditions of Heating 总被引:1,自引:0,他引:1
Vasile Cornelia Costea Elena Pascu Mihaela C. Warshawsky A. 《Journal of Thermal Analysis and Calorimetry》1998,52(2):569-579
Kinetic aspects of the first step of thermoxidative decomposition, under dynamic conditions of heating, of some polysulfones
have been studied.
The dependence of the kinetic parameters on the heating rate and conversion degree has been established. The compensation
effect and conversion function have also been discussed.
Polysulfone decomposes by the breaking of the main chain, a process involving very high activation energy.
Chemically modified polysulfones show the first step of thermoxidative decomposition at relatively low temperatures. This
step corresponds to the elimination of functional side - groups for the bromomethylated polysulfone while in the case of the
carboxylated polysolfone, the loss of the carboxyl group is probably accompanied by a crosslinking reaction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
133.
Popovici M Gich M Roig A Casas L Molins E Savii C Becherescu D Sort J Suriñach S Muñoz JS Baró MD Nogués J 《Langmuir : the ACS journal of surfaces and colloids》2004,20(4):1425-1429
Monoliths of iron oxide-silica aerogel nanocomposites have been synthesized using a novel synthesis route which consists of impregnating silica wet gels with anhydrous iron(II) precursors followed by ethanol supercritical drying of the gels. The process yields aerogels exhibiting high porosity, large surface areas (approximately 900 m2/g), rather low densities (approximately 0.6 g/cm3), and a homogeneous distribution of single-phase maghemite, gamma-Fe2O3, nanoparticles with average sizes in the 7-8 nm range. Remarkably, the gamma-Fe2O3 nanoparticles are obtained in the as-dried state without the need of postannealing. The nanoparticles are mostly superparamagnetic at room temperature but become blocked in a ferrimagnetic state at lower temperatures. 相似文献
134.
Synthesis of linear and star‐like poly(ε‐caprolactone)‐b‐poly{γ‐2‐[2‐(2‐methoxy‐ethoxy)ethoxy]ethoxy‐ε‐caprolactone} amphiphilic block copolymers using zinc undecylenate
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Katherine E. Washington Ruvanthi N. Kularatne Jia Du Matthew J. Gillings Jack C. Webb Nicolette C. Doan Michael C. Biewer Mihaela C. Stefan 《Journal of polymer science. Part A, Polymer chemistry》2016,54(22):3601-3608
Linear and star‐like amphiphilic diblock copolymers were synthesized by the ring‐opening polymerization of ε‐caprolactone and γ‐2‐[2‐(2‐methoxyethoxy)ethoxy]ethoxy‐ε‐caprolactone monomers using zinc undecylenate as a catalyst. These polymers have potential applications as micellar drug delivery vehicles, therefore the properties of the linear and 4‐arm star‐like structures were examined in terms of their molecular weight, viscosity, thermodynamic stability, size, morphology, and drug loading capacity. Both the star‐like and linear block copolymers showed good thermodynamic stability and degradability. However, the star‐like polymers were shown to have increased stability at lower concentrations with a critical micelle concentration (CMC) of 5.62 × 10?4 g L?1, which is less than half the concentration of linear polymer needed to form micelles. The star‐like polymeric micelles showed smaller sizes when compared with their linear counterparts and a higher drug loading capacity of doxorubicin, making them better suited for drug delivery purposes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3601–3608 相似文献
135.
We establish the Harnack inequality for advection-diffusion equations with divergence-free drifts by adapting the classical Moser technique to parabolic equations with drifts with regularity lower than the scale invariant spaces. 相似文献
136.
Gheorghe Ilia Mihaela Petric Lavinia Macarie Smaranda Iliescu Adriana Popa 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1717-1723
Aniline derivatives were phosphorylated in biphase systems using three methods. A comparative study was performed. The best results were obtained when a solid–liquid system was used. This method is the easiest and lead to higher yields (54–81%). 相似文献
137.
Zarafu Irina Olar Rodica Chifiriuc Mariana Carmen Bleotu Coralia Ioniţă Petre Mulţescu Mihaela Ioniţă Gabriela Grădişteanu Graţiela Tatibouët Arnaud Badea Mihaela 《Journal of Thermal Analysis and Calorimetry》2018,134(3):1851-1861
Journal of Thermal Analysis and Calorimetry - A series of Schiff bases resulted in the [1?+?1] condensation of 8-alkyl-2-hydroxy-tricyclo[7.3.1.02.7]-tridecan-13-one with the... 相似文献
138.
Alina Nicolescu Daniela Blanita Chiril Boiciuc Victoria Hlistun Mihaela Cristea Dorina Rotaru Ludmila Pinzari Ana Oglinda Adela Stamati Isabela Tarcomnicu Andreea Tutulan-Cunita Danae Stambouli Sergiu Gladun Ninel Revenco Natalia Uurelu Calin Deleanu 《Molecules (Basel, Switzerland)》2020,25(22)
The paper reports on monitoring methylmalonic aciduria (MMA)-specific and non-specific metabolites via NMR urinomics. Five patients have been monitored over periods of time; things involved were diet, medication and occasional episodes of failing to comply with prescribed diets. An extended dataset of targeted metabolites is presented, and correlations with the type of MMA are underlined. A survey of previous NMR studies on MMA is also presented. 相似文献
139.
Carmen Racles Viorica Gaina Mihai Marcu Maria Cazacu Mihaela Simionescu 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1605-1617
Abstract Organofunctional siloxane oligomers containing maleimide were synthesized by condensation reaction of α. ω-hydroxypropylsiloxane oligomers with n-[4-(chlorocarbonyl)phenyl]maleimide. A model compound [bis(maleimide-ester)disiloxane] was obtained to facilitate the characerization of the oligomers. Then, the heterogeneous catalyzed ring-opening cationic polymerization technique was applied to obtain an oligomer starting from the model compound and octamethylcyclotetrasiloxane. The structures of the resulting oligomers were confirmed by elemental analysis, IR and 1H-NMR spectroscopy. They were characterized by determining softening points, solubility and studying their thermal behavior by thermogravimetric (TGA and differential scanning calorimetry (DSC) measurements. 相似文献
140.