Flow-Induced Crystallization And Morphology In Poly (Ether Ketone Ketone) Nanocomposites With Dominant Influence From Carbon Nanotubes

Document Type

Article

Publication Date

2-9-2026

School

Polymer Science and Engineering

Abstract

Inclusion of nanomaterials and varying processing parameters can alter the crystallization rate and morphology of semi-crystalline polymers. This work investigates the influence of carbon nanotubes on PEKK crystallization rates and morphology under both quiescent (zero shear) and sheared conditions. We found that the inclusion of 0.1 wt% and 1 wt% carbon nanotubes accelerated crystallization in DSC, and nucleation density increased, evidenced by a transition from spherulitic to point-like morphology as observed by POM. Parallel plate rheology was used to apply shear and analyze crystallization through an increase in storage modulus. In neat PEKK, shear rates of 5 s−1 led to shear thinning in the melted material, which led to accelerated crystallization. Shearing the material at 30 s−1 and above led to a 20 °C increase in the crystallization onset temperature, and a bimodal behavior in the storage modulus evolution was observed during crystallization, which was attributed to a gradient of crystalline morphology in the sample: a transition from spherulitic, to point-like, to a highly aligned morphology in the direction of shear. Although the incorporation of CNTs hindered the relaxation of PEKK chains, crystallization rates in the nanocomposites remained largely unaffected by shear. Morphology also remained consistent under shear, indicating that heterogeneous nucleation from CNTs dominates over flow-induced crystallization. This behavior demonstrates the ability of CNTs to provide consistent morphology in PEKK nanocomposites despite variation in processing conditions.

Publication Title

Polymer

Volume

345

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