RESUMEN En el presente trabajo se describe la síntesis y caracterización de terpolímeros tribloqu... more RESUMEN En el presente trabajo se describe la síntesis y caracterización de terpolímeros tribloque ABC de polibutadieno–b–poli(oxido de etileno)–b–poli(–caprolactona) (PB–b–POE–b–PCL). La síntesis se realizó usando el método de titulación, en el que el grupo hidroxi terminal de un copolímero dibloque precursor polibutadieno–b–poli(oxido de etileno) se activó con difenilmetilsodio, para iniciar la polimerización de –caprolactona en benceno. Varios terpolímeros tribloque con diferente composición y con diferente peso molecular fueron obtenidos. El análisis estructural llevado a cabo mediante espectroscopia IRTF y RMN de 1 H mostró la presencia de los grupos funcionales característicos de los tres bloques presentes en cada producto de reacción. Los pesos moleculares fueron determinados mediante cromatografía de exclusión por tamaño (SEC), obteniéndose en todos los casos productos con curvas de distribución estrechas. Por otra parte, el análisis mediante calorimetría de barrido difere...
Page 1. Revista Iberoamericana de Polímeros Volumen 13(1), Enero de 2012 Contreras et al. Terpolí... more Page 1. Revista Iberoamericana de Polímeros Volumen 13(1), Enero de 2012 Contreras et al. Terpolímeros de bloque 29 Rev. Iberoam. Polim., 13(1), 29-40 (2012) SÍNTESIS Y CARACTERIZACIÓN DE TERPOLÍMEROS TRIBLOQUE ...
Revista Latinoamericana de Metalurgia y Materiales, May 31, 2011
En este trabajo se presenta el estudio de la degradacion en compost de mezclas de policaprolacton... more En este trabajo se presenta el estudio de la degradacion en compost de mezclas de policaprolactona y almidon de yuca termoplastico de diferentes composiciones, durante un periodo de 12 semanas. Se establecio, a partir de las medidas de perdida en peso y TGA, que el almidon es atacado de manera preferencial en las mezclas. A partir de ensayos tensiles se determino que la adicion de almidon disminuye las propiedades mecanicas de las mezclas. Se encontro tambien que las mezclas PCL/Almidon termoplastico forman dos fases inmiscibles entre si, y que el tamano de la fase dispersa aumenta conforme se incrementa el contenido de almidon. Finalmente, tanto la PCL pura como las diferentes mezclas estudiadas representan una potencial alternativa biodegradable a otros polimeros de uso convencional en algunas aplicaciones. This work presents a study of the degradation of polycaprolactone (PCL) and polycaprolactone / thermoplastic cassava starch blends under composting conditions, during 12 weeks time period. It was established, from weight loss and thermogravimetric analysis (TGA), that starch is preferentially attacked in the blends. The tensile tests showed that the addition of starch decreases the mechanic properties of the polycaprolactone. It was found that, the PCL/thermoplastic starch blends form an immiscible two phase system, where the disperse phase size becomes larger as the starch content increases. Finally, both the PCL and the blends studied represent a potential biodegradable alternative to conventionally employed polymers for specific applications.
... When T s is lower, partial melting is achieved and a large population of crystals is not melt... more ... When T s is lower, partial melting is achieved and a large population of crystals is not melted and therefore anneals during heat treatment at T s . Normally, three self-nucleation Domains can be ascribed to bulk crystallizable ... The SSA technique was developed by Müller et al. ...
... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in i... more ... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in immiscible polystyrene matrices. Mar??a L. Arnal,; Alejandro J. M??ller. Article first published online: 26 OCT 1999. ... Email: Alejandro J. M??ller (amuller@usb.ve). Publication History. ...
Blends of very low density polyethylene (VLDPE) and high density polyethylene (HDPE) were prepare... more Blends of very low density polyethylene (VLDPE) and high density polyethylene (HDPE) were prepared by melt extrusion. These blends exhibit a tendency to phase segregate when they are slow cooled from the melt. If they are cooled at increasingly faster rates, a finite population of co‐crystals can be isolated from the rest of the phase segregated material, indicating that this system is probably miscible in the melt but phase separates during cooling. Transmission electron microscopy observations are consistent with the blend melt miscibility since inter‐lamellar mixing was clearly appreciated in the samples examined. Other effects arising from interactions between the polymers were the nucleation of VLDPE rich phase by HDPE rich phase, and a melting point depression of HDPE rich phase caused by a dilution effect exerted by molten VLDPE rich phase. After a successive self‐nucleation and annealing thermal fractionation procedure is applied to the blends, phase separation dominates the behavior, although some small fraction of co‐crystals was still present.
... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in i... more ... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in immiscible polystyrene matrices. Mar??a L. Arnal,; Alejandro J. M??ller. Article first published online: 26 OCT 1999. ... Email: Alejandro J. M??ller (amuller@usb.ve). Publication History. ...
RESUMEN En el presente trabajo se describe la síntesis y caracterización de terpolímeros tribloqu... more RESUMEN En el presente trabajo se describe la síntesis y caracterización de terpolímeros tribloque ABC de polibutadieno–b–poli(oxido de etileno)–b–poli(–caprolactona) (PB–b–POE–b–PCL). La síntesis se realizó usando el método de titulación, en el que el grupo hidroxi terminal de un copolímero dibloque precursor polibutadieno–b–poli(oxido de etileno) se activó con difenilmetilsodio, para iniciar la polimerización de –caprolactona en benceno. Varios terpolímeros tribloque con diferente composición y con diferente peso molecular fueron obtenidos. El análisis estructural llevado a cabo mediante espectroscopia IRTF y RMN de 1 H mostró la presencia de los grupos funcionales característicos de los tres bloques presentes en cada producto de reacción. Los pesos moleculares fueron determinados mediante cromatografía de exclusión por tamaño (SEC), obteniéndose en todos los casos productos con curvas de distribución estrechas. Por otra parte, el análisis mediante calorimetría de barrido difere...
Page 1. Revista Iberoamericana de Polímeros Volumen 13(1), Enero de 2012 Contreras et al. Terpolí... more Page 1. Revista Iberoamericana de Polímeros Volumen 13(1), Enero de 2012 Contreras et al. Terpolímeros de bloque 29 Rev. Iberoam. Polim., 13(1), 29-40 (2012) SÍNTESIS Y CARACTERIZACIÓN DE TERPOLÍMEROS TRIBLOQUE ...
Revista Latinoamericana de Metalurgia y Materiales, May 31, 2011
En este trabajo se presenta el estudio de la degradacion en compost de mezclas de policaprolacton... more En este trabajo se presenta el estudio de la degradacion en compost de mezclas de policaprolactona y almidon de yuca termoplastico de diferentes composiciones, durante un periodo de 12 semanas. Se establecio, a partir de las medidas de perdida en peso y TGA, que el almidon es atacado de manera preferencial en las mezclas. A partir de ensayos tensiles se determino que la adicion de almidon disminuye las propiedades mecanicas de las mezclas. Se encontro tambien que las mezclas PCL/Almidon termoplastico forman dos fases inmiscibles entre si, y que el tamano de la fase dispersa aumenta conforme se incrementa el contenido de almidon. Finalmente, tanto la PCL pura como las diferentes mezclas estudiadas representan una potencial alternativa biodegradable a otros polimeros de uso convencional en algunas aplicaciones. This work presents a study of the degradation of polycaprolactone (PCL) and polycaprolactone / thermoplastic cassava starch blends under composting conditions, during 12 weeks time period. It was established, from weight loss and thermogravimetric analysis (TGA), that starch is preferentially attacked in the blends. The tensile tests showed that the addition of starch decreases the mechanic properties of the polycaprolactone. It was found that, the PCL/thermoplastic starch blends form an immiscible two phase system, where the disperse phase size becomes larger as the starch content increases. Finally, both the PCL and the blends studied represent a potential biodegradable alternative to conventionally employed polymers for specific applications.
... When T s is lower, partial melting is achieved and a large population of crystals is not melt... more ... When T s is lower, partial melting is achieved and a large population of crystals is not melted and therefore anneals during heat treatment at T s . Normally, three self-nucleation Domains can be ascribed to bulk crystallizable ... The SSA technique was developed by Müller et al. ...
... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in i... more ... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in immiscible polystyrene matrices. Mar??a L. Arnal,; Alejandro J. M??ller. Article first published online: 26 OCT 1999. ... Email: Alejandro J. M??ller (amuller@usb.ve). Publication History. ...
Blends of very low density polyethylene (VLDPE) and high density polyethylene (HDPE) were prepare... more Blends of very low density polyethylene (VLDPE) and high density polyethylene (HDPE) were prepared by melt extrusion. These blends exhibit a tendency to phase segregate when they are slow cooled from the melt. If they are cooled at increasingly faster rates, a finite population of co‐crystals can be isolated from the rest of the phase segregated material, indicating that this system is probably miscible in the melt but phase separates during cooling. Transmission electron microscopy observations are consistent with the blend melt miscibility since inter‐lamellar mixing was clearly appreciated in the samples examined. Other effects arising from interactions between the polymers were the nucleation of VLDPE rich phase by HDPE rich phase, and a melting point depression of HDPE rich phase caused by a dilution effect exerted by molten VLDPE rich phase. After a successive self‐nucleation and annealing thermal fractionation procedure is applied to the blends, phase separation dominates the behavior, although some small fraction of co‐crystals was still present.
... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in i... more ... Fractionated crystallisation of polyethylene and ethylene/??-olefin copolymers dispersed in immiscible polystyrene matrices. Mar??a L. Arnal,; Alejandro J. M??ller. Article first published online: 26 OCT 1999. ... Email: Alejandro J. M??ller (amuller@usb.ve). Publication History. ...
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