Federico Ohlmaier‐Delgadillo  Maria Monica Castillo‐Ortega  Rafael Ramírez‐Bon  Lorena Armenta‐Villegas  Dora Evelia Rodríguez‐Félix  Hisila Santacruz‐ Ortega  Teresa del Castillo‐Castro  Irela Santos‐Sauceda 《应用聚合物科学杂志》2016,133(48)

The preparation, characterization, and photocatalytic activity evaluation of three hybrid fibrous materials composed mainly by poly(methyl methacrylate) (PMMA), methyl methacrylate (MMA): 3‐(trimethoxysilyl) propyl methacrylate (TMSPM): titanium butoxide (TBT), TiO₂ nanoparticles (NPTiO₂), and TiO₂ nanowires (NWTiO₂) is studied. Two types of fibe?s structures were prepared, single and core‐shell structures. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed both structures, single and core‐shell, as well as the inorganic phase were dispersed in the hybrid fibers. Infrared spectroscopic analysis (FT‐IR) and thermal analysis showed the organic and inorganic components, as well as the weight percentage of the inorganic phase present in hybrid fibers. The photocatalytic activity of the hybrid fibers class I and II showed that the best photodegradative efficiency for methylene blue in aqueous solution (2.9 × 10^?5 M) was 95%, provided by PMMA—10 wt % NPTiO₂. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44334.  相似文献   

    

Rafael M. Santos  Jolien Thijs  Evangelos Georgakopoulos  Yi Wai Chiang  Ann Creemers  Tom Van Gerven 《Chemical Engineering Communications》2016,203(12):1671-1680

Precipitated aragonite can be synthesized at relatively low temperatures by combining the application of low-frequency sonication with the use of magnesium chloride additive, as demonstrated by our prior study. In the present study, new process conditions were found that promote aragonite formation while accelerating and increasing the reaction yield. It was found that Mg-to-Ca molar ratio of 3:1, together with higher slurry concentration (74 g/L Ca(OH)₂) and higher power-to-volume ratio (800 W/L gross, achieved by reducing slurry volume), promoted the aragonite formation while working at a higher CO₂ flow rate (2.0 NL/min), and consequently higher precipitated calcium carbonate production rate (1 g/(L · min) CaCO₃). The yield was thus improved while conserving the desired product properties as follows: high polymorph purity (95.7 wt%), small and narrow particle size distribution (D[3,2] = 0.74 µm), and unique shape (hubbard squash-like).  相似文献   

    

Hyun I. Kim  Geena L. Ferrelli  Rafael J. Zaldivar 《Journal of Adhesion Science and Technology》2016,30(23):2544-2556

Carbon fiber-reinforced composite replicated mirrors offer weight savings, higher stiffness, tailorable CTEs, higher thermal conductivities, and excellent damage tolerant mechanical properties in comparison to traditionally processed glass mirrors. These mirrors can also be rapidly manufactured by replicating the surface of a high-precision glass mandrel multiple times. The mold release coating used is critical and must be on the molecular scale, uniform, and exhibit low adhesion in order to produce high-fidelity replication. This study investigates the use of a self-assembled monolayer (SAM) as the mold release agent for the manufacture of replicated mirrors. We have synthesized and tested perfluoropolyether (PFPE) coatings formed on glass substrate via self-assembly. Ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy were used to characterize the morphology, thickness uniformity and the chemical profile of the coatings. The release force necessary to remove the replicated surfaces from the mandrel is critical and was directly related to the surface distortion of the replica. The release force increased with each successive replication due to pinholes and defects. Incorporating a secondary, lower molecular weight SAM reagent significantly reduced both surface agglomeration and transfer of SAM material to the replicated resin surface. A 60% reduction in the replica release force and a 50% improvement in the replica surface figure were achieved due to reductions in the defect density of the SAM coating.  相似文献   

    

Rafael Oliveira Defendi  Douglas Junior Nicolin  Paulo Roberto Paraíso  Luiz Mario de Matos Jorge 《Drying Technology》2016,34(3):360-371

Several researchers have developed studies to obtain a mathematical model able to describe grain drying kinetics. However, most of these studies neglect the effect of grain initial moisture content on drying curves. In this study, we assessed the dependence of drying curves and mass transfer coefficients on this initial moisture, air temperature, and its velocity by measuring grain mass losses within time on a tray dryer. Mathematical models were adjusted and results indicated that initial grain moisture content has significant influence on drying curves and mass transfer coefficients.  相似文献   

    

Hyun I. Kim  Brent A. Morgan  James P. Nokes  Rafael J. Zaldivar 《The Journal of Adhesion》2015,91(4):320-329

Quantitative assessment of adhesive bond strength on composite surfaces with respect to silicone contamination is presented and discussed. By using X-ray photoelectron spectroscopy, the precise surface contamination level was determined. When correlated with adhesive bond strength measurements, low-, medium-, and high-risk contamination levels were identified.  相似文献   

    

Mercedes Alemán  Ricard Bou  Javier Polo  Carmen Rodríguez  Alba Tres  Rafael Codony  Francesc Guardiola 《European Journal of Lipid Science and Technology》2016,118(2):195-207

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Abir Sadkaoui  Antonio Jiménez  Rafael Pacheco  Gabriel Beltrán 《European Journal of Lipid Science and Technology》2016,118(4):545-552

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Fatemeh Rajabi  Nafiseh Karimi  Mohammad Reza Saidi  Ana Primo  Rajender S. Varma  Rafael Luque 《Advanced Synthesis u0026amp; Catalysis》2012,354(9):1707-1711

Iron oxide nanoparticles supported on mesoporous silica‐type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as green oxidant. The supported catalyst could be easily recovered after completion of the reaction and reused several times without any loss in activity (no metal leaching observed during the reaction), constituting a facile and straightforward example of aqueous oxidation chemistry promoted by iron‐based heterogeneous systems.  相似文献   

    

Rafael A. García  A. Carrero  C. Martín  C. Domínguez 《应用聚合物科学杂志》2011,121(6):3269-3276

A linear low density polyethylene (LLDPE) obtained from a metallocene based catalyst, was blended in an extruder with a high density polyethylene (HDPE) homopolymer synthesized with an iron based catalyst. The bimodal polyethylenes, made with blends from 0 to 100 wt % of copolymer were characterized by SEC, DSC, ESEM, SEC‐FTIR, and TREF, while their resistance to the slow crack growth (SCG) was evaluated through the PENT test. Results provide that polymer blends with copolymer contents between 47.5 and 72.5 wt % are suitable for pipe applications. Furthermore, a method based on the intercrystalline tie chains calculus is proposed as suitable and attractive, because of its simplicity and novelty, to forecast long term performance and to predict capabilities. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

    

Leôncio Diógenes T. Câmara  Rafael S. Monteiro  Alex M. Constantino  Donato A. G. Aranda  Júlio C. Afonso 《Chemical Engineering Communications》2013,200(3):416-424

This work describes the oxidative cracking of n-alkanes with molecular oxygen at low temperatures (below 473 K) in an autoclave reactor. An increase of the oxygen consumption rate with increasing hydrocarbon size was observed. Data for n-hexadecane indicate that oxidative cracking is an autocatalytic reaction. The oxidation rate increased with the progress of the reaction. Low molecular weight compounds were formed as the main products. CG and CG-MS analyses of the liquid products found homologous series of oxygen compounds (acids, ketones, and ethers) and short-chain n-alkanes. Our results strongly suggest that oxidative cracking can be employed for processing heavy materials such as polymers and petroleum residues.  相似文献