We discuss the successful in situ synthesis of metal nanoparticles (NPs), such as copper, platinum and gold NPs, on a microstructured paper matrix composed of ceramic fibers as the main framework and zinc oxide (ZnO) whiskers as a selective scaffold for metal NPs synthesis. The as-prepared composite material, denoted metal NPs@ZnO paper, is lightweight, flexible and easy to handle, leading to excellent practical utility. The metal NPs@ZnO paper was used in a variety of catalytic reactions for energy, environmental applications and useful chemical synthesis. Its catalytic performance was far better than that of conventional catalytic materials. These results suggest that the combination of highly active metal nanocatalysts and a paper-specific porous microstructure, which allows effective diffusion of heat and reactants during catalytic reactions, provides significantly higher catalytic efficiencies. Therefore, metal NPs@ZnO paper composites are expected to be promising catalytic materials in future sustainable societies.

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Mechanical and morphological studies were made to clarify the mechanism for compressive behaviors of friction materials of automotive brake pad which were prepared by the compression molding of mixtures of aramid pulp (very short fibrous powders), potassium titanate (short inorganic fibers), barium sulfate (fine particles), zirconium silicate (fine particles), mica (flakes), cashew dust (organic particles) and phenolic resin (cross-linking agent). Mica and cashew dust were used as elastic materials which reduce Young's modulus of the brake pad. Porous structures of four kinds of friction materials as models for the automotive brake pad were examined by fluorescence microscopy and by scanning electron microscopy (SEM) with back scattered electron (BSE) image mode, which was first applied to the friction materials. Elastic properties of mica and cashew dust were successfully correlated with their morphologies obtained by the fluorescence microscopy and BSE-SEM. The present study was found to give important information in clarifying reduction of squeal (noise) generated at braking during driving.

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It was reported in our previous paper that the dispersion containing single cellulose nanofibers (= nanocellulose) was prepared from microbial cellulose pellicle using aqueous counter collision (ACC) method [1]. In this study, the nanocellulose has been investigated from the view point of a coating agent. Thus, various substrates such as a filter paper, polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP) films or sheets were coated with the nanocellulose, respectively. As a result for a hydrophilic substrate, both water and oil resistances on the surface of the nanofiber-coated filter paper were improved. On the other hand, coating with the same nanocellulose transformed the hydrophobic surface of PE, PET and PP sheets into the hydrophilic. This indicated that the nanocellulose, which was originated from microbial cellulose pellicle, had an effect switching surface properties depending on characteristics of substrates, differing from the wood cellulose nanofibers. Namely, the nanocellulose was preferably coated and adsorbed with the surface of substrates, whereas wood cellulose nanofibers prepared using ACC method and the homogenized pellicle did not accomplish such a behavior. Moreover, the dyeing as well as the improvement in water and oil resistances was performed simultaneously by coating using a mixture of nanocellulose with a dyeing agent.

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