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Highly thermally conductive carbon nanotube/polybenzimidazole polymer nanofiber composites were produced by core-shell electrospinning. The in-plane thermal conductivity increased by factor of 50 for 1.94 %wt. carbon nanotubes in the composite nanofibers. The high thermal conductivity results from the excellent nanotube alignment in the core of the polymer fiber and the use of liquid crystal polybenzimidazole as a matrix and shell polymer. Polymer composites are useful for heat dissipation in electronic packaging and other applications. Compared to metal matrices polymers are light weight, which is key for mobile applications [1]. Other advantages of polymers include chemical resistance, lower electrical conductivity and mechanical flexibility. Carbon nanotubes (CNT) are outstanding thermal conductors with conductivities up to 3000 W/mK [2]. Randomly oriented CNTs in polymer composites, however, generally results in poor heat dissipation with λ = 0.1-1 W/mK for up to 50 %wt. CNT loading [3]. The thermal conductivity increases by an order of magnitude upon alignment of the nanotubes, e.g., by external fields or through flow-induced orientation. Many alignment techniques, however, either require functionalization of the CNTs or are incompatible with industrial composite production [4]. In this paper, we report a mat of CNT-filled nanofibers with in-plane thermal conductivity of almost 20 W/mK for less than 2 %wt. nanotube content. The nanofibers are produced by electrospinning of polybenzimidazole (PBI) loaded with carbon nanotubes. An important advantage of our technique is the use of pristine, as-grown CNTs. The nanotubes are aligned

The building industry makes a great effort to reduce energy consumption. The use of nanotechnology is one of the approaches to surpassing the properties of conventional insulation materials. In this work, an industrial cost‐effective method to manufacture highly porous materials with excellent thermal insulation properties is described. The materials are prepared from polystyrene recovered from the building sector and electrospun as nanofiber‐based sheets. Varying electrospinning parameters allow controlling the morphology of the produced materials. The materials are obtained with differences in interfiber and inner‐fiber porosity and morphology. The thermal conductivity of the freestanding and compressed materials is evaluated. Those differences affect the insulation performance: the materials with higher interfiber porosity show better thermal insulation in the freestanding state. An increase of the inner‐fiber porosity leads to better insulation in the compressed samples. Insertion of carbon nanomaterials reduces the effects of the infrared Radiation. Nanofiber‐based insulation materials from the recycled expanded polystyrene (EPS) show thermal conductivity values of 20 to 25 mW/mK (ie, 20% to 30% below the thermal conductivity of the commercial EPS). The effect of integrating polystyrene nanofiber sheets into conventional wall‐building materials is also investigated in terms of thermal insulation. The nanofiber insulation sheets are sandwiched between two pieces of the building materials resulting in a drastic increase of the insulation effect. The materials have a great potential in using, for example, as thermal insulation for the restoration of historic buildings in the narrow central parts of the old towns.

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