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Control de la forma de las distribuciones de peso molecular en la polimerización de coordinación y su impacto en las
Renee J Sifri1, Omar Padilla-Vélez1, Geoffrey W Coates1
1Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853-1301 , United States.
Journal of the American Chemical Society
|December 28, 2019
Resumen
El control de la forma de distribución del peso molecular (MWD) en polietileno de alta densidad (HDPE) afecta a las propiedades reológicas como la viscosidad, pero no a la resistencia del material. Esto permite el procesamiento de HDPE a medida sin comprometer el rendimiento.
Área de la Ciencia:
- Química de los polímeros
- Ciencias de los materiales
- Reología
Sus antecedentes:
- El polietileno de alta densidad (HDPE) es un polímero ampliamente utilizado conocido por sus propiedades físicas versátiles y su rentabilidad.
- Si bien el peso molecular y la dispersión influyen en las propiedades del HDPE, el impacto de la distribución del peso molecular (MWD) sigue siendo poco explorado.
Objetivo del estudio:
- Investigar cómo la forma de la distribución del peso molecular (MWD) influye en las propiedades físicas del polietileno de alta densidad (HDPE).
- Establecer un método sistemático para el estudio de los efectos de la forma del MWD mediante el control de la iniciación de la polimerización.
Principales métodos:
- Se utiliza la regulación temporal de la iniciación en la coordinación de la inserción de polimerización de etileno para controlar con precisión la forma del MWD.
- Se realizaron pruebas reológicas para analizar la viscosidad compleja y el comportamiento de adelgazamiento del corte.
- Se realizan pruebas de tracción para evaluar la deformación en la rotura.
Principales resultados:
- Los ensayos reológicos demostraron diferencias claras en la viscosidad compleja y el adelgazamiento del corte basado en la dirección de la inclinación del MWD (oposición de la inclinación del MWD).
- Las pruebas de tracción indicaron que la inclinación de MWD no afectó significativamente la deformación en la rotura, una medida clave de la resistencia del material.
Conclusiones:
- La forma del MWD en HDPE puede modificarse para influir en las características de procesamiento, como la viscosidad y el adelgazamiento por corte.
- Lo más importante es que la alteración de la forma de MWD no compromete la resistencia fundamental del material (deformación en la rotura) del HDPE.
- Esta investigación proporciona una vía para optimizar el procesamiento de HDPE para aplicaciones específicas sin sacrificar la integridad mecánica.
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