Engineering the Interphase of Single Wall Carbon Nanotubes/Polyacrylonitrile Nanocomposite Fibers with Poly(methyl methacrylate) and Its Effect on Filler Dispersion, Filler–Matrix Interactions, and Tensile Properties

Abstract

Mechanical reinforcement of polymer nanocomposites with pristine single wall carbon nanotubes (SWNTs) beyond 1 wt % loading is challenging because SWNT−SWNT contacts generate filler aggregation and reduce polymer−filler interaction. Furthermore, SWNTs cannot be covalently functionalized without affecting their inherent properties. In this study, filler individualization and filler−matrix interactions were tuned by helically wrapping the SWNTs with poly(methyl methacrylate) (PMMA), a noncovalent method, and also by changing the PMMA molecular weight. Polyacrylonitrile nanocomposite fibers were produced by dry-jet wet spinning using 1 and 5 wt % PMMA-wrapped SWNTs. Improvement in the filler dispersion and the fiber mechanical properties upon using PMMA-wrapped SWNTs, as compared to SWNTs without PMMA-wrapping, is reported. It is demonstrated that PMMA-wrapping becomes part of the filler−matrix interphase. Increasing the molecular weight of the PMMA wrapping improves SWNT individualization but appears to reduce filler−matrix interaction. Relatively high fiber mechanical properties were obtained when SWNTs wrapped with relatively low molecular weight (15000 g/mol) PMMA were used. Potential applications of these fibers have been discussed.

The effects of processing and carbon nanotube type on the impact strength of aerospace‐grade bismaleimide based nanocomposites

“…To investigate the cause of the reduced impact strength in the nanocomposites, we first used Raman spectroscopy to examine any cure-induced stresses (tension or compression) in the CNT A (Figure 3). Raman spectroscopy has been employed in prior studies [60,61] for evaluating the tensile stress at the polymer-CNT interface, where the polymer-nanocomposites were stretched under a Raman spectroscope and their Raman spectra collected. The tensile strain in the CNTs results in a downshift of the Raman band frequencies (D $ 1300 cm À1 , G $ 1580 À1 , and G 0 $ 2600 À1 ) due to the weakening of C═C bonds.…”

Interaction of Poly(methyl acrylate) with Carbon Nanotubes as a Function of CNT Diameter, Chirality, and Temperature

“…PMMA modification of SWCNTs can increase the stability of homogeneous dispersions in DMF beyond 1 year due to regular helical wrapping of the polymer onto CNTs, supported by X-ray data and molecular simulations . PMMA modification was also found to increase filler dispersion and filler–matrix interactions in PMMA films and in PAN fibers . In addition, the degree of homogeneously dispersed carbon nanotubes in poly­(ethylene-methyl acrylate)/multiwalled carbon nanotube (PEMA/MWCNT) composites was shown to depend on the mass percentage of methyl acrylate .…”

“…23 PMMA modification was also found to increase filler dispersion and filler−matrix interactions in PMMA films 10 and in PAN fibers. 24 In addition, the degree of homogeneously dispersed carbon nanotubes in poly-(ethylene-methyl acrylate)/multiwalled carbon nanotube (PEMA/MWCNT) composites was shown to depend on the mass percentage of methyl acrylate. 25 A higher degree of dispersion of carbon nanotubes increased the thermal stability of the composites due to hindered diffusion of decomposition products at high temperature.…”

Cure Behavior Changes and Compression of Carbon Nanotubes in Aerospace Grade Bismaleimide-Carbon Nanotube Sheet Nanocomposites

“…Next, we explored the effect of the cure of BMI on the CNTs within the nanocomposite. Raman spectroscopy has been used in prior studies for evaluating the tensile , or compressive stress , on the CNTs in the nanocomposites. In our prior work, CNTs were radially and axially compressed upon the cure of BMI in the nanocomposites containing 0.1 wt % pristine or functionalized CNTs.…”