Nanocomposites of polyamide‐11 and carbon nanostructures: Development of microstructure and ultimate properties following solution processing

Abstract

There is growing interest in the incorporation of nanoparticles into engineering polymers to improve various functional properties. However, ultimate properties of nanocomposites are affected by a large number of factors including the microstructural distributions that are generated during processing. In this work, polyamide-11 (PA-11) (also known as nylon-11) nanocomposites are generated with carbon nanostructures employing a solution crystallization technique at multiple polymer and nanoparticle concentrations, followed by drying, molding, uniaxial stretching and the analysis of the microstructural distributions and tensile properties of the nanocomposites. The morphology of crystals of PA-11 encapsulating the nanoparticles changed from nano-hybrid shish-kebabs at low polymer concentration (0.02 wt % PA-11 in solvent) to spherulites at high polymer concentration (10 wt % PA-11 in solvent). The drawing down of nanocomposite films at draw ratios ranging from 2 to 5 at 100 C resulted in a shift of the PA-11 polymorph from the generally-encountered a phase to the technologically interesting c phase (which is the crystal phase attributed to the piezoelectric and pyroelectric properties of PA-11). The drawing down also increased of the tensile modulus and yield stress of the nanocomposite films. In contrast, the a phase was conserved at a drawdown temperature of 150 C, which was attributed to the resulting smaller normal force, i.e., the normal stress difference and the higher temperature allowing the partial relaxation of some of the macromolecules. These findings illustrate how PA-11 can be structured in the presence of carbon nanotubes and nanofibers to achieve enhanced functionality, which could broaden the application areas and utility of this polymer.

Highly dispersed polyamide‐11/halloysite nanocomposites: Thermal, rheological, optical, dielectric, and mechanical properties

“…The appearance of this shoulder peak is attributed to the melting of preferentially oriented PA-11 macromolecules, such an orientation being explained by the presence of the rigid nanofillers. 21 The degree of crystallinity (X c ) of PA-11 increases with the addition of HNTs. This is consistent with the crystallization behavior of other semi-crystalline polymers in the presence of halloysites, such as PP 28 and PA-6.…”

“…Liu et al 19 mentioned a negligible enhancement in mechanical properties of PA-11 even at high organoclay loadings which was ascribed to incomplete exfoliation of nanoparticles. Mago et al 21 reported a significant improvement in modulus and strength upon addition of CNTs and carbon nanofiber to PA-11, but decreased toughness. 21 Recently, Stoclet et al 22 obtained exfoliated PA-11/ clay nanocomposites by water-assisted extrusion process and observed significant enhancement in the mechanical properties and thermal stability.…”

Stiffening mechanisms in vermiculite–amorphous polyamide bio-nanocomposites

“…Polymer nanocomposites are high performance materials promising to meet new application requirements and to replace existing materials [1][2][3]. Adding clay-based nanoparticles can significantly improve properties such as heat resistance, stiffness, strength, toughness, impact resistance, barrier properties, rheological properties, flame retardancy, etc.…”

Microstructural Characterization and Mechanical Properties of PA11 Nanocomposite Fibers

“…Based on our knowledge, there are just a few papers that investigate nanocomposites made of PA11 with MWCT (Ref [19][20][21][22] but not in the form of fibers. We have already published the general procedure of fabrication PA11 fibers and non-woven fabrics doped with MWCT ( Ref 23).…”