Flexible Thermal Protection Polymeric Materials with Self-Sensing and Self-Adaptation Deformation Abilities

Based on the strategy of killing two birds with one stone, we introduce thermally expandable microspheres into a silicone rubber matrix to fabricate temperature-responsive controllable deformation materials, which exhibit intelligent deformation properties as well as enhanced thermal protection performance, for dynamic thermal protection in the next-generation morphing aircrafts. The formation of hollow structures endows the material with intelligent thermal management ability and makes the thermal conductivity controllable, meeting the requirements of rapid deformation and excellent thermal insulation. The dimensions of the material adaptively expand with increasing temperature, and a constant 50N force can be provided to ensure reliable sealing. Moreover, benefiting from the synergistic effect of the hollow structure and zinc borate in the ceramization process of the silicone rubber, the 10 mm thick material can reduce the temperature from 2000 to 63 °C, and the mass ablation rate is only 4.8 mg/s. To broaden the application of our material, a sensor with a sandwich structure composed of different functional layers is designed. It is pleasantly surprising to observe that the sensor can provide real-time remote warning of fire and overheating sites with a response time as short as 1 s. This synergistic strategy opens a new possibility to fabricate intelligent thermal protection materials.

Interlaminar Toughening of Epoxy Carbon Fiber Reinforced Laminates: Soluble Versus Non-Soluble Veils

This work describes the evaluation of different interlaminar veils to improve the toughening of epoxy/carbon fiber composites manufactured by resin infusion. Three commercial veils have been used in the study: two electro spun thermoplastic nanofiber (Xantulayr^® from Revolution Fibres) with different areal weight, and one micro carbon fibers veil (Optiveil^® from TFP). Two laboratory made veils were also manufactured by electrospinning commercial polyethersulfone (PES) tougheners (Virantage by Solvay). The veils were selected to be either soluble or non-soluble in the epoxy resin matrix during curing. The solubility was analyzed by scanning electron microscopy and dynamic mechanical analysis testing on the cured laminates. The fracture energy was evaluated by double cantilever bending (DCB) testing under Mode I loading. The insoluble thermoplastic nanofibers showed the highest toughening efficiency, followed by the soluble nanofiber veils. The carbon fiber based veil showed no toughness improvement.

Photoluminescent epoxy microspheres: preparation, surface functionalization via grafting polymerization and photophysical properties

Photoluminescent epoxy microspheres with the size of 1–3 μm were prepared. Their surfaces were functionalized with poly(N-vinylpyrrolidone) via RAFT polymerization.

Synthesis of cross-linked epoxy microparticles: effect of the synthesis parameters

Epoxy crosslinked microparticles were synthesized from the reaction between diglycidyl ether of bisphenol A and a diamino hardener, through precipitation polymerization in a polypropylene glycol solvent. The influence of the monomer concentration, the amine/epoxy stoichiometric ratio, the reaction temperature and the structure of the diamine (aromatic or cycloaliphatic) were investigated, since these parameters may affect the structure and properties of the particles. Morphological analysis revealed that, in all cases, spherical particles were obtained with diameters ranging from 1 to 6 μm. The glass transition temperatures of the particles was found to vary between 130 and 160 °C using the aromatic diamine and between 116 and 141 °C using the cycloaliphatic diamine. It was also found that the effective stoichiometry of the particles was different from the initial stoichiometry in the feed solution.