Elsevier

Polymer

Volume 36, Issue 11, 1995, Pages 2143-2152
Polymer

Polymer paper
Crystalline morphology of polyamide-6 near planar surfaces

https://doi.org/10.1016/0032-3861(95)95289-DGet rights and content

Abstract

The crystalline morphology and the orientation in thin films of polyamide-6 crystallized on polystyrene- or ethylene-propylene-diene rubber-coated silicon substrates were analysed by transmission electron microscopy (TEM), X-ray and electron diffraction. Bright-field TEM imaging of thin films demonstrated that lamellae organize into disc-shaped crystals, or ‘discoids’, when the film thickness is below 0.5 μm. A model is presented for the organization of lamellae and the polyamide-6 chains in the lamellae of the discoids. In the inter-discoid regions, the films are semicrystalline and the lamellae fill the space randomly. Orientation studies by means of electron diffraction and wide-angle X-ray scattering showed that in relatively thin films (< 0.5 μm) the (0 0 2) hydrogen-bonded planes are parallel to the surface of the film. This orientation gradually diminishes as the film thickness increases. The change in orientation affects the mechanical properties: under uniaxial tension, the modulus and the flow stress of the films increase with decreasing thickness, hence with increasing orientation.

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      Film thickness is the most influential parameter on the obtained film morphology. Thicker films tend to induce edge on lamellae, while in thinner films the flat on orientation is preferred [48,59–76]. However, a general value for the transitional thickness may not exist, according to Liu and Chen [59], since this value depends on several parameters, such as polymer and substrate type and their interactions.

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