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Elucidación de la conformación de la cadena en un poliéster vidrioso, PET, por RMN bidimensional
Schmidt-Rohr1, Hu, Zumbulyadis
1K. Schmidt-Rohr and W. Hu, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA. N. Zumbulyadis, Imaging Research and Advanced Development, Eastman Kodak Company, Rochester, NY 14650-2132, USA.
Science (New York, N.Y.)
|May 13, 1998
Resumen
Las conformaciones de las cadenas de poli (tereftalato de etileno) (PET) se estudiaron utilizando resonancia magnética nuclear (RMN). El PET amorfo muestra conformaciones de gauche significativas, lo que afecta las propiedades del material de poliéster.
Área de la Ciencia:
- La ciencia de los polímeros es la ciencia de los polímeros.
- Ciencia de los materiales Ciencia de los materiales.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- El poli (tereftalato de etileno) (PET) es un poliéster muy utilizado.
- Comprender la conformación de su cadena es crucial para predecir las propiedades del material.
- El PET vítreo existe tanto en estados cristalinos como amorfos con diferentes arreglos de cadena.
Objetivo del estudio:
- Para caracterizar la conformación de la cadena del polietileno tereftalato (PET) vidrioso.
- Para cuantificar las estadísticas del ángulo de torsión en PET amorfo y cristalino.
- Para correlacionar la conformación de la cadena con las propiedades materiales potenciales de los poliéster.
Principales métodos:
- Se utilizó la espectroscopia de resonancia magnética nuclear (RMN) bidimensional de doble cuántico.
- Empleó el etiquetado de carbono-13 para mejorar la detección de señales de RMN.
- Se analizaron patrones espectrales de RMN para diferenciar entre las conformaciones trans y gauche.
Principales resultados:
- El PET cristalino exhibe una transconformación del 100%.
- El PET amorfo contiene aproximadamente un 14% de conformación trans.
- Se determinó un ángulo de torsión izquierdo promedio de 70 grados para el PET amorfo.
Conclusiones:
- La conformación de la cadena del PET difiere significativamente entre los estados cristalino y amorfo.
- La prevalencia de las conformaciones gauche en el PET amorfo influye en sus características físicas.
- Estos hallazgos proporcionan información sobre las relaciones estructura-propiedad de los poliéster.
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