Estudio cinético de la síntesis en masa de poliuretanos de 1,6-hexamtilen diisocianato y distintos glicoles de baja masa molecular

Los poliuretanos (PU) segmentados presentan tal versatilidadque permiten diseñar materiales con distintas propiedadesmecánicas, tales como alta elasticidad, resilienciay alta tenacidad de fractura. El estudio sistemático de lamorfología y propiedades de distintos bloques de poliuretanopermite entender su contribución en las propiedadesfinales de los PU sintetizados a partir de distintos bloques.En este trabajo se estudia la cinética de síntesis en masade poliuretanos formados a partir de 1,6-hexametilen diisocianato(HDI) y cinco distintos glicoles de baja masa molecularque difieren en su estructura y composición química:1,4-butanodiol (BD), etilenglicol (EG), propilenglicol (PPgli),N-metil dietanolamina (MDEA) y 3-metil 1,5-pentanodiol(3MPD). También se discute algunos aspectos morfológicosde los PUs formados a partir de estos dioles. La exotermicidadde la reacción estequiométrica entre el HDI y losglicoles sigue el orden MDEA > PPgli > EG > BD > 3MPD.Las velocidades de reacción siguen aproximadamente elorden MDEA > PPgli > BD > 3MPD > EG. La diferenciaentre el orden de exotermicidad y de cinética de curadoparecen ser influidas por las viscosidades de los glicolesasí como por las características de los PU formados

Copolímeros de poliuretano del tipo poli[(hexametilen-carbamato- butanodiol)-co-(carbonato-co-éster)]

Resumen Los poliuretanos segmentados termoplástico elastoméricos (PUSTE) comprenden una familia de materiales muy versátiles debido a su potencial empleo en diversos campos tales como biomedicina. Entre los PUSTE los formados por policarbonatos dioles y diisocianatos alifáticos son especialmente atractivos debido a su bioestabilidad y biocompatibilidad. En este trabajo se presentan los resultados del análisis morfológico y conducta mecánica de una familia de PUSTEs formados por 1,6-hexametilen diisocianato (HDI), 1,4-butanodiol (BD) y un copolímero cauchoso de policaprolactona y polihexametilen carbonato diol, PCL-b-PHMC-b-PCL, sintetizados con distinta relación entre bloques rígidos (HDI-BD) y copolímero cauchoso.Segmented thermoplastic polyurethane elastomers (PUSTE) comprise a family of very versatile materials with large potential for their applicability in different fields such as biomedicine. Among the PUSTEs the ones formed by polycarbonates diols and aliphatic diisocyanates are especially attractive due to their bioestability and biocompativility. In this work we present the results of morphological and mechanical characterization of different PUSTEs formed by 1,6-hexamethyene diisocyanate, 1,4-butanediol and a copolymer of polycaprolactone and polyhexamethylene carbonate diol, PCL-b-PHMC-b-PCL, synthesized with different ratios between rigid (HDI-BD) segments and the rubbery copolymer

The effect of ultra-thin graphite on the morphology and physical properties of thermoplastic polyurethane elastomer composites

[EN] Composites of thermoplastic polyurethane (TPU) and ultra-thin graphite (UTG) with concentrations ranging from 0.5 wt.% to 3 wt.% were prepared using a solution compounding strategy. Substantial reinforcing effects with increased loadings are achieved. Compared to neat TPU, values for storage modulus and shear viscosity are enhanced by 300% and 150%, respectively, for UTG concentrations of 3 wt.%. Additionally, an enhancement of thermal properties is accomplished. The crystallization temperature and thermal stability increased by 30 C and 10 C, respectively, compared to neat TPU. Furthermore, the use of oxidized UTG (UTGO) with its added functional oxygen groups suggests the presence of chemical interactions between UTG and TPU, which additionally impact on the thermal properties of the corresponding composites. Controlling the oxidation degree, thus offers further possibilities to obtain composites with tailored properties. The presented approach is straightforward, leads to homogeneous TPU-UTG composites with improved materials properties and is especially suitable for commercial UTG materials and further up-scaled production.This research was supported by IMPIVA under Project (IMIDIP/2010/58), Spanish Ministry of Science and Innovation (MICINN) under Project MAT2010-15026, CSIC under Project 201080E124, and the Government of Aragon (DGA) and the European Social Fund (ESF) under Project DGA-ESF-T66 CNN. M.C. thanks MICINN and ESF for her Grant No. BES-2008-003503. Authors thank Merquinsa S.L. (Barcelona, Spain) and Avanzare S.L. (La Rioja, Spain) for kindly providing polyurethane and ultra-thin graphite samples, respectively.Menes, O.; Cano, M.; Benedito, A.; Giménez Torres, E.; Castell, P.; Maser, WK.; Benito, AM. (2012). The effect of ultra-thin graphite on the morphology and physical properties of thermoplastic polyurethane elastomer composites. Composites Science and Technology. 72(13):1595-1601. https://doi.org/10.1016/j.compscitech.2012.06.016S15951601721

Kinetic studies of the polymerization of an epoxy resin modified with rhodamine B

Novel fluorescent materials were satisfactorily synthesized. With this aim, an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) was reacted with a laser dye, rhodamine B (RB), to achieve an epoxy-based prepolymer. Then, a diamine, m-xylylenediamine (MXDA), was used as hardener with the purpose of obtaining a crosslinked polymer. The curing conditions strongly influence the intended final properties and the optimization of the curing requires a reliable kinetic model. For that reason, this work presents the kinetic study of the polymerization of the epoxy resin by differential scanning calorimetry (DSC) in isothermal mode as well as by Fourier transform infrared spectroscopy (FTIR). DSC data were fitted using a Kamal autocatalytic equation. Conversion as a function of reaction time curves obtained by means of both techniques agreed well. In addition, the synthesized epoxy-based materials were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR) and their fluorescent properties were also analysed.Fil: Fernández, Raquel. Universidad del País Vasco; EspañaFil: Fernández d’Arlas, Borja. Universidad del País Vasco; EspañaFil: Oyanguren, Patricia Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Mondragon, Iñaki. Universidad del País Vasco; Españ

Synthesis and characterization of polyurethane rigid foams from soybean oil-based polyol and glycerol

Mixtures of biomass-derived polyols were used to synthesize rigid polyurethane (PU) foams. A commercial polymerized methylene diphenyl diisocyanate (pMDI) was used as crosslinker, and distilled water served as foaming agent. The morphology and mechanical properties of foams with different glycerol and water contents were compared in order to evaluate the most suitable formulations. The rigid foams with higher water contents had larger and more anisotropic cells, explaining their lower density. Compressive moduli ranged from about 2.5 MPa to above 20 MPa and collapse stresses from 55 kPa to more than 1 MPa for densities between 54 and 143 kg/m3. Densification strain did not depend on the density or on the composition of the polymeric matrix. Moreover, results shown herein demonstrate that an increase in the glycerol content leads to an increase in the required pMDI for the synthesis of the PU, but with a negligible change in the mechanical properties of the prepared foams.Fil: Altuna, Facundo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Fernández d’Arlas, Borja. Universidad del País Vasco; EspañaFil: Corcuera, M. Angeles. Universidad del País Vasco; EspañaFil: Eceiza, Arantxa. Universidad del País Vasco; EspañaFil: Aranguren, Mirta Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Stefani, Pablo Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Kinetic and thermodynamic studies of the formation of a polyurethane based on 1,6-hexamethylene diisocyanate and poly(carbonate-co-ester)diol

This paper presents the kinetic and thermodynamic characterization of a non-catalyzed reaction between poly(hexamethylene carbonate-co-caprolactone)diol (PHMC-co-PCL) and aliphatic hexamethylene diisocyanate (HDI) with a stochiometric functional concentration, using both isothermal and dynamic differential scanning calorimetry, DSC, as well as Fourier transform infrared spectroscopy, FT-IR. DSC data were fitted using a Kamal autocatalytic equation. Model-free-isoconversional methods were also applied to analyse the conversion dependence of the global activation energy. This relation was used to predict the reaction conversion versus time pattern at different temperatures and to compare it with that of the model approach. Kinetic modelling and model-free analysis successfully described the conversion versus time curves. The reaction can be divided in two different paths: the forward path and the autocatalyzed one. Results corroborated that autocatalysis is promoted by the urethane group. Activation energies for both reaction paths have been found to be higher than those presented in the literature for aromatic diisocyanate systems, which explains the lower reaction rate of the presented system. © 2007 Elsevier B.V. All rights reserved.Fil: Fernández d’Arlas, Borja. Euskal Herriko Unibertsitatea; EspañaFil: Rueda, L.. Euskal Herriko Unibertsitatea; EspañaFil: Stefani, Pablo Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: de la Caba, K.. Euskal Herriko Unibertsitatea; EspañaFil: Mondragon, I.. Euskal Herriko Unibertsitatea; EspañaFil: Eceiza, A.. Euskal Herriko Unibertsitatea; Españ

Surface modification of muitiwalled carbon nanotubes via esterification using a biodegradable polyol

Multiwalled carbon nanotubes (MWCNT) were surface modified firstly oxidizing them with a H 2SO 4/HNO 3 mixture to obtain more reactive carboxylic groups on their surface and then higher functionality. Secondly the oxidized nanotubes (MWCNT-COOH) were dispersed in tetrahydrofuran (THF) and made react via esterification with a poly(hexamethylene carbonate-co-caprolactone)diol, a potentially biodegradable polyol with hydroxyl groups at its ends. Modification process steps were characterized using Fourier transform infrared spectroscopy, FT-IR, ultraviolet spectroscopy, UV, solubility in different solvents, thermo-gravimetric analysis, TGA, as well as atomic force microscopy, AFM. Results suggest that surface carboxylic groups are reactive enough to graft polymer chains onto their surface. © 2009 American Scientific Publishers.Fil: Fernández d’Arlas, Borja. Universidad del País Vasco; EspañaFil: Goyanes, Silvia Nair. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Rubiolo, Gerardo Hector. Universidad de Buenos Aires; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Mondragon, Iñaki. Universidad del País Vasco; EspañaFil: Corcuera, M. A.. Universidad del País Vasco; EspañaFil: Ezeiza, A.. Universidad del País Vasco; Españ