RESUMO
A carbon fiber-reinforced polymer (CFRP) is a light and rigid composite applicable in various fields, such as in aviation and automobile industry. However, due to its low thermal conductivity, it does not dissipate heat sufficiently and thus accumulates heat stress. Here, we reported a facile and effective strategy to improve the through-thickness thermal conductivity of CFRP composites by using a layer-by-layer coating of inorganic crystals. They could provide efficient heat transfer pathways through layer-by-layer contact within the resulting composite material. The high thermally conductive CFRP composites were prepared by employing three types of inorganic crystal fillers composed of aluminum, magnesium, and copper on prepreg through the layer-by-layer coating process. The vertical thermal conductivity of pure CFRP was increased by up to 87% on using magnesium filler at a very low content of 0.01 wt %. It was also confirmed that the higher the thermal conductivity enhancement was, the better were the mechanical properties. Thus, we could demonstrate that the layer-by-layer inclusion of inorganic crystals can lead to improved through-thickness thermal conductivity and mechanical properties of composites, which might find applications in varied industrial fields.
RESUMO
We herein report a simple approach to the preparation of gas-forming polyacrylonitrile/polymethyl-methacrylate/methylcyclohexane core-shell nanocapsules for the desorption of optical adhesive films. The proposed gas-forming core-shell nanocapsules are based on a shell structure composed of a polyacrylonitrile/polymethylmethacrylate copolymer, where the core contains vaporizable cyclic hydrocarbons (i.e., methylcyclohexane). These stable functional nanocapsules were spherical in shape, with an average particle size of ~110 nm. Interestingly, using the proposed synthetic method, it was also possible to prepare nanoparticles with varying particle sizes and copolymer ratios through a simple pre-emulsification stage and careful control of the monomer ratio employed. Upon mixing the resulting core-shell nanocapsules uniformly with the optical adhesive films, desorption was observed between layers following heat treatment. Furthermore, the high optical transmittance of the optical adhesive film was retained due to the small size of the core-shell nanoparticles. It was therefore apparent that the proposed method should be applicable for the preparation of future optical films where functional core-shell nanocapsules are required.
RESUMO
Nanoscale self-assembled molecular layers of 1-pyrene carboxylic acid, 1-pyrene butylic acid, and 1-amino pyrene were employed as photoluminescent alignment agents to form vertical arrays of liquid crystals (LCs). The LC device using alignment agent of 1-amino pyrene appeared to have a stable vertical alignment based on crossed polarization analysis. The electro-optical properties of the LCs fabricated using this self-assembled layer exhibited better performance than those of general LC cells containing a conventional polyimide layer. The proposed self-assembled alignment method is sufficient as a replacement for more commonly used polyimide layers, which require complex film forming processing and high production costs; conversely, the proposed technique allows for simple mixing using low concentrations of alignment agents (0.05 wt%). Moreover, as LCs were mixed with the pyrene derivatives, photoluminescence (PL) under ultraviolet (UV) light was exhibited. This proposed method has excellent LC alignment and PL property, both of which can be utilized in advanced display technologies for next-generation LC devices, such as polyimide-free alignment or color-filter-free color expression.
