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

Abstract

The pressing issues of the energy crisis and rapid electronics development have sparked a growing interest in the production of highly thermally conductive polymer composites. Due to the challenges related to the poor processability of hybrid materials and filler distribution to achieve high thermal conductivity, electrospinning is employed to create composite nanofibers and yarns using polyimide (PI) and thermally conductive silicon nitride (SiN) nanoparticles. The thermal performance of the individual nanofibers is evaluated using scanning thermal microscopy (SThM), providing significant insights into their heat transfer performance. Next, the nanofibers are applied as coatings on resistance wires to assess the thermal conductivity and insulation properties. Notably, the samples containing 35 wt.% of SiN exhibit a 25% increase in surface temperature. These innovative materials hold great promise as exceptional candidates for smart textiles and thermal management applications, addressing the growing demand for effective heat dissipation and regulation.

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

“…Moreover, the peaks at 1529 and 1066 cm –1 are attributed to the N–H bending and C–O–C bands, respectively. − The spectrum of the BN nanoparticles shows strong absorption peaks at 1286 and 725 cm –1 , corresponding to the stretching and bending vibration of B–N, respectively. − As can be seen in the magnified spectra in Figure a, the addition of BN nanoparticles to the TPU mats resulted in peaks with higher intensity in the regions of BN characteristic peaks, confirming the presence of BN nanoparticles in the mats. Similarly, as shown in magnified spectra in Figure b, the mats, including SiN nanoparticles, have a higher intensity of peaks in the region 700–1000 cm –1 , where the SiN nanoparticle spectrum demonstrates the broad peak of Si–N stretch band at 844 cm –1 . , …”

“…The TPU mat performed very well during tensile testing with strain at failure (ε f ) over 500% and a maximum stress (σ max ) of around 1.3 MPa. However, the addition of high concentrations of BN and SiN nanoparticles lowered the σ max of the TPU–BN and TPU–SiN mats, see Figure d; yet, the obtained values still fall within the range of mechanical properties of electrospun mats used in heat-transfer applications. − This is due to the nanoparticle agglomerate formation, which induces structural defects within the composite mats and serves as stress concentration points. ,, The scanning electron microscopy (SEM) images of the samples after the tensile tests, see Figure e–g, confirmed the rupture of the composite fibers close to the agglomerations of nanoparticles. However, compared to the TPU–BN samples, TPU–SiN mats showed higher σ max over 1 MPa.…”

“…Similarly, as shown in magnified spectra in Figure 3b, the mats, including SiN nanoparticles, have a higher intensity of peaks in the region 700−1000 cm −1 , where the SiN nanoparticle spectrum demonstrates the broad peak of Si−N stretch band at 844 cm −1 . 54,55 The results from the mechanical testing of randomly oriented fibers are presented in Figure 3c, which shows the representative stress−strain curves of the samples. The TPU mat performed very well during tensile testing with strain at failure (ε f ) over 500% and a maximum stress (σ max ) of around 1.3 MPa.…”

“…The lower temperature means higher thermal conductivity of the material and, consequently, higher heat dissipation of the tip through the material. 31,54,66 Figure 4b summarizes the result of the SThM measurement on the electrospun fibers and the ITO glass. The average tip's temperature was lower on the composite fibers compared to the TPU fibers, indicating an enhanced thermal conductivity due to the addition of highly thermally conductive BN and SiN nanoparticles.…”

“…A method similar to our previous work was used to prepare the samples and conduct the measurements. 54 In brief, the samples were prepared by shortly electrospinning on the ITO glass (Ossila, UK) attached to the collector. The temperature on the cantilever's tip was set to 85.7− 85.9 °C by adjusting the laser position.…”