Noriyuki Hirano

Study of fiber length and fiber-matrix adhesion in carbon-fiber-reinforced polypropylenes

Carbon-fiber-reinforced polypropylenes often exhibit insufficient mechanical properties because of low affinity between the carbon fibers (CFs) and the matrix resins. From the viewpoint of designing materials with better properties, it is important to control the interfacial properties. In this study, the interfacial properties are quantified in terms of the interfacial shear strength (IFSS), and the relationships among the IFSS, composite strength, and impact resistance are evaluated. When the fiber length is sufficiently short (as in injection-molded materials), the composite strength and impact resistance improve with increasing IFSS. On the other hand, when the fiber length is longer, the impact resistance improves with decreasing IFSS. Longer CFs with low IFSS require higher energy to pull out from the matrix resin than that required for interfacial debonding.

Discovery of potent transient receptor potential vanilloid 1 antagonists: Design and synthesis of phenoxyacetamide derivatives

We aimed to discover a novel type of transient receptor potential vanilloid 1 (TRPV1) antagonist because such antagonists are possible drug candidates for treating various disorders. We modified the structure of hit compound 7 (human TRPV1 IC50=411 nM) and converted its pyrrolidino group to a (hydroxyethyl)methylamino group, which substantially improved inhibitory activity (15d; human TRPV1 IC50=33 nM). In addition, 15d ameliorated bladder overactivity in rats in vivo.

Temperature-dependent constant fatigue life diagram for press-formed short carbon fiber reinforced polyamide composite

Fatigue strength of a short carbon fiber reinforced polyamide (SCF/PA) composite fabricated using a press forming technique is examined. Unlike an injection-molded SCF/PA composite, this one exhibits in-plane isotropy as well as through-thickness uniformity. Fatigue tests on the SCF/PA composite are carried out at different stress ratios and temperatures, respectively. The fatigue test results show that the S–N relationship for the SCF/PA composite significantly depends on stress ratio, and fatigue degradation occurs most rapidly at the critical stress ratio, regardless of test temperature. The fatigue stress for a given life decreases with temperature. The reduction in fatigue strength with temperature correlates well with the reduction in static strength with temperature. Accordingly, the effect of temperature on fatigue life for each of different constant values of stress ratio can approximately be removed by normalizing fatigue stress with respect to static strength. The full shape of constant fatigue life diagram for the press-formed SCF/PA composite is identified for each of different test temperatures. It is shown to incline toward the direction of positive mean stress, regardless of test temperature. A difference in shape of CFL diagram between the press-formed and injection-molded composites is addressed. This study demonstrates that the anisomorphic constant life diagram approach with temperature as the parameter allows adequately predicting the constant fatigue life diagram and thus the S–N curve for the SCF/PA composite over the whole range of mean stress at any temperature in the tested range.