This study reported moisture absorption of untreated and treated individual water hyacinth (WH) fibers as well as comparison the mechanical properties of WH fibersunsaturated polyester (UPR) matrix composites after and before immersion in water. The result shows that the individual WH fibers treated with various alkali concentration did not exhibit significantly decreases of their moisture absorption. SEM photograph in cross section of the treated WH fibers shows swollen cell wall containing more nano and micro hollows. Tensile and flexure strength of the wet composite samples are lower than that of dried ones. However, increases volume fraction of the WH fibers in UPR matrix affected slightly on enhancement mechanical properties of the composite samples.

Characteristics of Screw Pine fiber of species Pandanus Odoratissimus (PO fibers) and short PO fibers reinforced composite were studied. The results show that various alkali concentrations changed ability of PO fibers in absorptions of moisture, chemical compositions and cross-sectional area. The untreated and treated PO fibers were compounded with unsaturated polyester to evaluate their mechanical properties. The treated PO fiber composites exhibit high mechanical properties in comparison with untreated ones. SEM photographs revealed a different fracture surface between untreated PO fiber-reinforced composites and treated ones.

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Ultrafine-grained pure titanium (Ti) plates with the thickness of 1 mm were fabricated by a combined process of multi-directional forging (MDFing) and cold rolling (here after referred as MDFed pure Ti for simplicity) aiming at the dental implant application. The plates exhibited higher tensile strength than the conventional cold-rolled pure Ti plates due to the ultrafine-grained structure with an average size of 200 nm. The axial fatigue tests were conducted in laboratory air and in Ringer's solution to investigate long-term durability as dental implants. The fatigue strengths of the MDFed pure Ti plates in laboratory air were higher than those of the cold-rolled pure Ti plates as well as the tensile properties. In the high cycle fatigue (HCF) regime, sub-surface crack initiation with fish-eye fracture surface was observed in the MDFed pure Ti plates, while surface crack initiation was dominant in the cold-rolled pure Ti plates. Sub-surface crack generally initiated at the mid-thickness of the thin plates. Inclusions were not recognized at the crack initiation sites, while microstructural analyses revealed that some coarse grains with the size of a few µm distributed around the crack initiation sites. Consequently, the sub-surface crack initiation mechanism was attributed to the inhomogeneity of the microstructure near the mid-thickness of the plates. The corrosion fatigue strengths in Ringer's solution were comparable to those in laboratory air, where sub-surface crack initiation occurred in the HCF regime even in corrosive environment. That indicates the high corrosion resistance of the MDFed pure Ti plates.