Electrically insulating polymeric nanocomposites with enhanced thermal conductivity by visible-light curing of epoxy-boron nitride nanotube formulations

Form Factor-Free Boron Nitride Nanotube-Agarose Composites for Neutron Shielding

Boron nitride nanotubes (BNNTs) have remarkable mechanical and thermal properties and are suitable for neutron shielding due to boron. Because BNNTs exist in bundled and stiff shapes, limiting their practical applications, however, it is essential to improve their formability and processability. In this study, we demonstrate form-factor-free BNNTs and agarose composites for use in neutron shielding for the first time; they are fabricated by mixing hydrophilic agarose with noncovalently functionalized water-soluble BNNTs (p-BNNTs). The mechanical properties of the agarose/p-BNNT composite films surpass those of conventional commodity plastics. When the p-BNNT concentration increased, the neutron linear attenuation coefficient of the composite film increases from 0.574 ± 0.010 to 0.765 ± 0.062 mm-1, which is comparable to that of conventional rigid shielding materials. In particular, the addition of 10 wt % p-BNNTs to agarose results in excellent form-factor flexibility, neutron shielding, and mechanical properties, thus rendering it a promising candidate for the nuclear industry.

Investigation of the Thermal Conductivity of Silicon-Base Composites: The Effect of Filler Materials and Characteristic on Thermo-Mechanical Response of Silicon Composite

Thermal conductivity is a key property in many applications from electronic to informatics. The interaction of fillers with Sylgard 184 was studied; this study explores new composites and the influence of metal particles (copper and nickel), carbon-based materials (carbon nanotubes and carbon black), and ceramic nanoparticles (boron nitride) as fillers to enhance thermal properties of silicon-based composites. The effect of the fillers on the final performances of the composite materials was evaluated. The influence of filler volume, dimension, morphology, and chemical nature is studied. Specifically, FT-IR analysis was used to evaluate curing of the polymer matrix. DSC was used to confirm the data and to further characterize the composites. Thermo-mechanical properties were studied by DMTA. The filler morphology was analyzed by SEM. Finally, thermal conductivity was studied and compared, enlightening the correlation with the features of the fillers. The results demonstrate a remarkable dependence among the type, size, and shape of the filler, and thermal properties of the composite materials. Underlining a that the volume filler influenced the thermal conductivity obtaining the best results with the highest added volume filler and higher positive impact on the k of the composites is reached with large particles and with irregular shapes. In contrast, the increase of filler amount affects the rigidity of the silicon-matrix, increasing the rigidity of the silicon-based composites.

3D Printing of PDMS-Like Polymer Nanocomposites with Enhanced Thermal Conductivity: Boron Nitride Based Photocuring System

This study demonstrates the possibility of forming 3D structures with enhanced thermal conductivity (k) by vat printing a silicone-acrylate based nanocomposite. Polydimethylsiloxane (PDSM) represent a common silicone-based polymer used in several applications from electronics to microfluidics. Unfortunately, the k value of the polymer is low, so a composite is required to be formed in order to increase its thermal conductivity. Several types of fillers are available to reach this result. In this study, boron nitride (BN) nanoparticles were used to increase the thermal conductivity of a PDMS-like photocurable matrix. A digital light processing (DLP) system was employed to form complex structures. The viscosity of the formulation was firstly investigated; photorheology and attenuate total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) analyses were done to check the reactivity of the system that resulted as suitable for DLP printing. Mechanical and thermal analyses were performed on printed samples through dynamic mechanical thermal analysis (DMTA) and tensile tests, revealing a positive effect of the BN nanoparticles. Morphological characterization was performed by scanning electron microscopy (SEM). Finally, thermal analysis demonstrated that the thermal conductivity of the material was improved, maintaining the possibility of producing 3D printable formulations.

Kale M, Divakaran N, Senthil T, P. S, Wu L, Wang J. A Novel Approach to Enhance Mechanical and Thermal Properties of SLA 3D Printed Structure by Incorporation of Metal-Metal Oxide Nanoparticles

Silver (Ag) ornamented TiO₂ semiconducting nanoparticles were synthesized through the sol-gel process to be utilized as nanofillers with photo resin to enhance the mechanical and thermal properties of stereolithography 3D printed objects. The as-prepared Ag-TiO₂ nanoparticles (Ag-TNP) were typified and qualified by XRD, XPS, Raman, and FESEM; TEM analysis dissected the morphologies. The enhancement in the tensile and flexural strengths of SLR/Ag-TNP nanocomposites was noted as 60.8% and 71.8%, respectively, at the loading content of 1.0% w/w Ag-TNP within the SLR (stereolithography resin) matrix. Similarly, the thermal conductivity and thermal stability were observed as higher for SLR/Ag-TNP nanocomposites, equated to neat SLR. The nanoindentation investigation shows an excerpt hike in reduced modulus and hardness by the inclusion of Ag-TNP. The resulted thermal analysis discloses that the introduction of Ag-TNP can appreciably augment the glass transition temperature (T_g), and residual char yield of SLR nanocomposites remarkably. Hence, the significant incorporation of as-prepared Ag-TNP can act as effective nanofillers to enhance the thermal and mechanical properties of photo resin.