Beyond Percolation Threshold Loading of Polyacrylonitrile Electrospun Nanofibers with Boron Nitride Nanotubes for Use in High-Temperature Composites

Abstract

Boron nitride nanotubes (BNNTs) have unique thermomechanical properties that make them excellent candidates for use in structural heat resistant composites, but their usage has been limited in the past due to difficulties associated with dispersing the material into a usable configuration. Techniques to facilitate dispersion into solution, such as functionalization and surface activation of the BNNTs, alter and degrade desirable properties of the material, and high surface energies of BNNT make it difficult to obtain sufficient concentrations to take advantage of those properties by using conventional mixing techniques. This research demonstrates homogeneously dispersed electrospinning sol−gel solutions of up to 20 wt % unfunctionalized boron nitride nanoparticles (BNPs) and BNNTs in polyacrylonitrile (PAN) by using a novel high g-load mixing technique. It confirms that the BNPs and BNNTs influenced bulk PAN properties such as glass transition temperature (T g ) and tensile strength. It also indicates that the BNNTs were loaded beyond the percolation threshold, and the load-bearing structure of the electrospun composite transitioned to a stable core of interconnected nanofiller due to increasing levels of boron nitride present. This was evident by the increase in tensile strength of the composite and in the creation of a stable mat of interconnected BNNTs after PAN pyrolysis. The research highlights the advantages of utilizing unfunctionalized material and points to the success of high g-loading as a viable mixing technique for high weight percentage of unfunctionalized BNNTs.

Bridging a Gap in Thermal Conductivity and Heat Transfer in Hybrid Fibers and Yarns via Polyimide and Silicon Nitride Composites

“…Higher concentrations of SiN led to an increased formation of nanoparticle agglomerates, which act as stress concentration points and introduce structural defects within the composite meshes. [28,[30][31][32] As is evident in Figure 2d, the breakage of the composite nanofibers happened around the nanoparticle agglomerates, which supports the observed mechanical performance of the samples. However, the addition of the nanoparticles also deteriorated the ductility of the meshes as the strain at maximum stress (𝜖 max ) and strain at failure decreased with the increase of SiN concentration.…”

Unraveling the Impact of Boron Nitride and Silicon Nitride Nanoparticles on Thermoplastic Polyurethane Fibers and Mats for Advanced Heat Management

“…Compared to the pristine TPU fibers, which had a density of 1.2 g cm –3 , TPU–BN and TPU–SiN fibers showed densities of 1.35 and 1.38 g cm –3 , respectively, see Figure e. This indicates the successful incorporation of the nanoparticles. , …”

“…This indicates the successful incorporation of the nanoparticles. 43,44 Chemical Analysis and Mechanical Properties. The chemical composition of the electrospun mats, as well as BN and SiN nanoparticles, was characterized by ATR−FTIR, see Figure 3a,b.…”

Energy-Harvesting Performance in a LaYFe2O6/P(VDF-HFP) Nanocomposite by Boosting the Magnetoelectric Effect

“…Owing to higher ME coefficient/coupling strength, the generated voltage is also high in this case; hence, the PS10 film-based device has been chosen for further studies. Now, we see whether there are any percolative impacts in the performance of the nanogenerators. Due to the high resistive nature of the PVDF-HFP matrix and filler LO, a bare PVDF-HFP film and composite films offer very high resistance (such that it goes beyond the measurement limit of the instrument).…”