Structural Changes from the Pure Components to Nylon 6−Montmorillonite Nanocomposites Observed by Solid-State NMR

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Abstract

Multinuclear solid-state NMR was used to characterize the molecular structures in nylon 6−montmorillonite nanocomposites in comparison with the two pure components. Both the polymer and the clay were studied. ²⁷Al two-dimensional multiple quantum magic angle spinning (MQMAS) measurements reveal the existence of an additional four-coordinated aluminum site in the nanocomposites compared to in the pure clay. This site is most probably induced by interactions of the polymer chains with the silicate surface. A highly mobile component is observed only in the ¹H NMR spectra of all nanocomposite samples, whose relative content increases with increasing clay content and which is generated during the extrusion process. High-resolution ¹H and ¹³C NMR spectra of these mobile molecules are recorded and assigned to be a tertiary amine that is formed during the melt extrusion process as a result of the loss of one methyl group of the organic modifier dimethyl di(hydrogenated tallow) ammonium ion. As a result of the presence of paramagnetic Fe³⁺ inside the clay, the proton spin−lattice relaxation time of the polymer is strongly influenced. This effect can be used to get information on the degree of clay exfoliation. It was found that at higher clay contents on average just two platelets are stuck together. With this, the distance between clay platelets is calculated and correlated with the analysis of TEM (transmission electron microscopy) measurements. ¹⁵N cross-polarization magic angle spinning (CPMAS) spectra show an increase of the fraction of the γ-crystalline phase at the cost of the α-crystalline phase upon increasing clay content.

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This article has been cited by 3 ACS Journal articles (3 most recent appear below).

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  Chemistry of Materials2011 Article ASAP

  • Direct Observation of the Intergallery Expansion of Polystyrene–Montmorillonite Nanocomposites

    Ranya Simons, Greg G. Qiao, Stuart A. Bateman, Xiaoqing Zhang, and Peter A. Lynch
    Chemistry of Materials2011 Article ASAP

    The intergallery expansion development of a series of differently modified montmorillonite polystyrene nanocomposites was directly observed with time-resolved in situ small-angle X-ray scattering (SAXS) using synchrotron radiation. The results indicated ...

    Abstract | Full Text HTML | Hi-Res PDF | PDF w/ Links
• 

  Evolution of Clay Morphology in Polypropylene/Montmorillonite Nanocomposites upon Equibiaxial Stretching: A Solid-State NMR and TEM Approach

  Bo Xu, Johannes Leisen and Haskell W. Beckham, Rund Abu-Zurayk, Eileen Harkin-Jones and Tony McNally
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  • Evolution of Clay Morphology in Polypropylene/Montmorillonite Nanocomposites upon Equibiaxial Stretching: A Solid-State NMR and TEM Approach

    Bo Xu, Johannes Leisen and Haskell W. Beckham, Rund Abu-Zurayk, Eileen Harkin-Jones and Tony McNally
    Macromolecules2009 42 (22), 8959-8968

    Solid-state NMR and TEM were used to quantitatively examine the evolution of clay morphology upon equibiaxial stretching of polypropylene/montmorillonite (PP−MMT) nanocomposites up to a stretch ratio (λ = final length/initial length) of 3.5. 1H spin−...

    Abstract | Full Text HTML | Hi-Res PDF | PDF w/ Links
• 

  Crystallization Kinetics and Crystal Structure of Nylon6-Clay Nanocomposites: Combined Effects of Thermomechanical History, Clay Content, and Cooling Conditions

  V. Miri, S. Elkoun, F. Peurton, C. Vanmansart, J.-M. Lefebvre, P. Krawczak and R. Seguela
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  • Crystallization Kinetics and Crystal Structure of Nylon6-Clay Nanocomposites: Combined Effects of Thermomechanical History, Clay Content, and Cooling Conditions

    V. Miri, S. Elkoun, F. Peurton, C. Vanmansart, J.-M. Lefebvre, P. Krawczak and R. Seguela
    Macromolecules2008 41 (23), 9234-9244

    The crystallization behavior and the crystalline structure of nylon6-clay nanocomposites are investigated with regard to the processing conditions and thermal treatment. Microextruded bulk samples as well as blown films are under concern. The often ...

    Abstract | Full Text HTML | Hi-Res PDF | PDF w/ Links

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