Sintesis
Mostrando 13-24 de 47 artigos, teses e dissertações.
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13. Síntesis de hidrogeles de acrilamida en soluciones acuosas de etanol
The polymerization of acrylamide was performed in aqueous ethanol solutions, varying the concentration of ethanol in the solution; obtaining both nanogels as macrogels. The water absorbing capacity of the macrogels were found; obtaining materials with a capacity to absorb from 40 to 90 g of water per gram of xerogel and the particle size of the nanogels are
Polímeros. Publicado em: 2014-12
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14. Poliuretanos obtenidos a partir de aceite de higuerilla modificado y poli-isocianatos de lisina: síntesis, propiedades mecánicas y térmicas y degradación in vitro
Biodegradable polyurethanes (PUR) were prepared from polyols derived from castor oil by transesterification of pentaerythritol-modified castor oil and lysine polyisocyanates (LDI and LTI). The polyurethanes obtained were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA).
Quím. Nova. Publicado em: 2014
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15. La invención de la imprenta y los libros incunables
"Este libro surgió del trabajo de identificación y reseña de los libros incunables de la Biblioteca Antigua del Archivo Histórico de la Universidad del Rosario, labor que puso en evidencia la conveniencia de revisar y poner al día la información disponible sobre ellos. Con una finalidad pedagógica, el autor se propone suministrar información clara, completa y actualizada de los libros más antiguos que se conservan en esta biblioteca, abarcando los nueve incunables en sentido estricto (impresos antes de 1500) y treinta incunables en sentido amplio (impresos entre 1500 y 1530), todos ellos de gran valor. Para tal fin, primero se ofrece una síntesis de la historia del libro, de suma importancia para comprender distintos términos y conceptos que se utilizan en el contexto de los primeros libros impresos, para después explicar las principales características de los libros incunables, complementándolas con soportes gráficos tomados de los ejemplares que hacen parte del catálogo de la Biblioteca Antigua. Esta obra aspira a convertirse en punto de partida de posteriores investigaciones, lo que redundará en un mejor conocimiento y una valoración más justa de los tesoros patrimoniales del Colegio Mayor de Nuestra Señora del Rosario."
Autor(es): Restrepo Zapata, Jaime
Editorial Universidad del Rosario. Publicado em: 2014
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16. Síntesis en medio poli-alcohólico y caracterización de Perovskitas BaHfO3 y BaZrO3
Perovskite materials (ABO3) present considerable technological interest, their properties depend on the A and B elements. A variety of methods have been used for the elaboration of perovskite materials. In the present paper we present the results of the BaHfO3 and BaZrO3 obtained by polyol method. Inorganic salts of barium and hafnium or zirconium were disso
Matéria (Rio J.). Publicado em: 2013-12
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17. Síntesis de hidrogeles termosensibles de poli(N‑isopropilacrilamida)-co-poli(N,N,-dimetilacrilamida)
In this paper we copolymerized N-isopropylacrylamide (NIPA) with N, N, dimethylacrylamide (DIMA). The increase in the proportion of DIMA added resulted in a proportional increase over the transition temperature, as well as on the ability of samples to absorb water. An increase in the DIMA concentration also reduced the volumetric fraction and the rate of wat
Polímeros. Publicado em: 19/04/2013
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18. Cristalización de zeolita beta mediante conversión asistida por vapor: influencia de los parámetros de síntesis
In the present work, beta zeolites were prepared by an alternative route called steam-assisted conversion (SAC). Several zeolites were synthesized using amorphous dry gels with a low SDA concentration (0.09 mol, TEAOH). Temperature and crystallization time were the main parameters studied. X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning elec
Quím. Nova. Publicado em: 2013
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19. Síntesis química, estudios de caracterización y reactividad de un material catalítico a base de ZrO2-H3PW12O40
In this work, the preparation and characterization of materials such as zirconium oxide (ZrO2) and phosphotungstic acid promoted zirconium oxide (ZrO2-H3PW12O40) is presented. Physico-chemical characterization results showed that addition of H3PW12O40 acted as both a textural and chemical promoter of zirconium oxide. The incorporation of phosphotungstic acid
Quím. Nova. Publicado em: 2013
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20. Síntesis de microcápsulas de poliurea a partir de aminas renovables, mediante doble emulsificación
This paper reports on the microencapsulation of a commercial perfume by means of a double emulsification, where the polyurea shell was synthesized by the reaction of lysine with two commercial di-isocyanates (aromatic and aliphatic). In the synthesis the factors evaluated were the amine:di-isocyanate molar ratio and the type of emulsifier. The particle size
Polímeros. Publicado em: 13/05/2011
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21. Síntesis de poli ácido láctico y poli ricinoleato empleando calentamiento por microondas y su utilización en la producción de termoplasticos de poliuretano
In this paper we report on the synthesis of thermoplastic polyurethane (TPU) using oligomers synthesized from DL Lactic acid and ricinoleic acid. These polyols were obtained from renewable sources by polycondensation of monomers without catalysts. The effect of microwaves on the reactions was evaluated, where non-thermal effects were found to lower the activ
Polímeros. Publicado em: 13/05/2011
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22. Síntesis de espumas rígidas de poliuretano obtenidas a partir de aceite de castor y poliglicerol empleando calentamiento por microondas
In this work we showed the polyurethane rigid foams synthesis using a macropolyol synthesized from castor oil and polyglycerol. This process is optimized employing a response surface analysis and using a 3² factorial design. The factors evaluated were: amount of water and tartaric acid, where tartaric acid acts as crosslinking agent and catalyst; mechanical
Polímeros. Publicado em: 11/02/2011
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23. Síntesis y caracterización de adhesivos reposicionables de poliuretano dispersos en agua, obtenidos a partir de aceite de castor maleinizado
This work focused on the production of aqueous dispersions of polyurethane using the emulsification method by phase inversion. For the synthesis two polyols were employed, viz. a commercial polyester and Maleinizated Castor Oil (MACO), with two diisocyanates: one aromatic, toluene diisocyanate (TDI) and another aliphatic, hexamethylene diisocyanate (HDI), wh
Polímeros. Publicado em: 11/06/2010
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24. Síntesis de una matriz cuasiceramica destinada a la obtención de fundentes aglomerados para proceso SAW y evaluación cinético-termodinámica de su proceso de humectación
In the this paper is presented a conception of the synthesis by sinterización at relative low temperature, of an amorphous cuasiceramic matrix to be used in agglomerated flux in the SAW process. In the design of the cuasiceramic it was made a valuation of the chemical composition of the diferent mineral concentrates (feldspar, zeolite and calcite), as well
Soldagem & Inspeção. Publicado em: 2010-06