Kiyoshi Uzawa

Effect of molding condition on flexural strength of textile carbon fiber reinforced polycarbonate laminates

The effects of molding conditions on the flexural strength of textile carbon fiber reinforced polycarbonate laminates were assessed. Choosing the temperature and pressure conditions appropriately during hot-press molding using carbon fiber textile layers and polycarbonate films can produce void-free, high interfacial adhesion in textile carbon fiber reinforced polycarbonate laminates. Those characteristics were confirmed from observing the cross-sections of carbon fiber reinforced polycarbonate laminates and measuring the interlaminar shear strength. A suitable molding condition can raise the flexural strength of carbon fiber reinforced polycarbonate laminates to a level predicted from the measured flexural strength of textile carbon fiber/epoxy laminates by assuming carbon fiber micro-buckling in the compression side of specimens.

Lignocellulose nanofibers prepared by ionic liquid pretreatment and subsequent mechanical nanofibrillation of bagasse powder: Application to esterified bagasse/polypropylene composites

In the present study, we examined the efficacy of choline acetate (ChOAc, a cholinium ionic liquid))-assisted pretreatment of bagasse powder for subsequent mechanical nanofibrillation to produce lignocellulose nanofibers. Bagasse sample with ChOAc pretreatment and subsequent nanofibrillation (ChOAc/NF-bagasse) was prepared and compared to untreated control bagasse sample (control bagasse), bagasse sample with nanofibrillation only (NF-bagasse) and with ChOAc pretreatment only (ChOAc-bagasse). The specific surface area was 0.83m2/g, 3.1m2/g, 6.3m2/g, and 32m2/g for the control bagasse, ChOAc-bagasse, NF-bagasse, and the ChOAc/NF-bagasse, respectively. Esterified bagasse/polypropylene composites were prepared using the bagasse samples. ChOAc/NF-bagasse exhibited the best dispersion in the composites. The tensile toughness of the composites was 0.52J/cm3, 0.73J/cm3, 0.92J/cm3, and 1.29J/cm3 for the composites prepared using control bagasse, ChOAc-bagasse, NF-bagasse, and ChOAc/NF-bagasse, respectively. Therefore, ChOAc pretreatment and subsequent nanofibrillation of bagasse powder resulted in enhanced tensile toughness of esterified bagasse/polypropylene composites.

Mechanical, thermal, and interfacial shear properties of polyamide/nanoclay nanocomposites: Study the effect of nanoclay on the micromechanism of fracture

There are increasing interests in using thermoplastics to replace thermosets to laminate fabrication due to their advantages such as high toughness, shorter manufacturing cycles, and reprocessing possibilities. The aim of the current study is to select appropriate thermoplastic nanocomposites, which fit the requirements of carbon fiber (CF) composites in the automotive industry. In order to achieve the target, this research has investigated the effect of nanoclay on the mechanical, thermal, and interfacial properties with de-sized CF of polyamide (PA6) composites. PA6/clay composites were characterized by different properties, namely, bending, tensile, impact, heat distortion temperature, interfacial shear stress, and scanning electron microscope. The micromechanism of plastic deformation after bending failure of PA6-clay nanocomposites is examined with different contents of nanoclay to correlate the microstructures with the mechanical properties. The results revealed that with 3% organo-clay filler content, flexural strength and modulus improved significantly by 42% and 52%, respectively, which could be explained by scanning electron microscopy images that show rougher fracture surface with adding clay into the PA6 matrix. The increased surface roughness implies that the path of the crack tip is distorted because of the silicate nano-layer, making crack propagation more difficult. The interfacial shear strength for 1 wt% of nanoclay was about the same as the neat PA6 but decrease dramatically with increasing contents of nanoclay.

Effect of stamping condition on age deformation of textile carbon fiber reinforced polycarbonate laminates

This study examines the effect of stamping condition on age deformation after stamping of textile carbon fiber reinforced polycarbonate laminates. The laminates were stamped to a hat shape at various stamping temperatures between the glass transition temperature Tg and the melting temperature Tm of polycarbonate. Then the age deformation, which is the hat angle variation, was measured. Results show that the age deformation occurs at the stamping temperature in the vicinity of Tg. The age deformation is suppressed when the stamping temperature is sufficiently higher than Tg. Furthermore, the long-term age deformation as the dimensional stability was predicted from the measured deformation at elevated temperature based on the time–temperature superposition principle for the viscoelasticity of the polycarbonate matrix.

Improving Interfacial Adhesion of Sub-Micro PA6 Composites with De-Sized Carbon Fiber

In our previous study we showed the the potential of using of sub-micro Alumina/Titanium (ALTi) particles as a multifunctional reinforcement which can produce multifunctional polymer composites. This paper aims to investigate the interfacial shear properties for different contents of ALTi particles incorporated into PA6 with de-sized carbon fiber. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Sizing removal can reduce the acid parameter of carbon fibers surface promoting bonding strength at the fiber/matrix interface which is a desirable property for the carbon fiber composites. XPS also, showed that epoxide group still appeared with using acetone treatment while disappeared with conventional heating at the oven for 25min ate 450oC. SEM images did not show any damage for the carbon fiber after heat treatment. Interfacial shear strength (IFSS) showed an improvement in interfacial adhesion with de-sizing carbon fiber than neat PA6.

Formability of Braided CFRTP Cylindrical Pipe in Pipe Bending

Carbon fiber reinforced thermoplastic (CFRTP) is able to change a shape after molding by re-heating. By using the characteristic, we contrived a CFRTP pipe which can be re-shaped at an on-site, for example, in construction work or in earthwork. In this study, we estimated bend property of CFRTP pipe. The CFRTP pipes which had various Vf and braiding angle were prepared by using braid with commingled yarn, and by using low compression molding with heat shrink tube. The commingled yarn was composed of carbon fiber and polyamide12 fiber. The CFRTP pipes had 4 plies, 25mm of outside diameter, and 22mm of inside diameter. The CFRTP pipes were bent into U-shaped of radius 90mm, after heating 190°C. As the results, CFRTP pipe which had 40% of Vf and 50 degrees of braiding angle could be bent well without fold or void.

Novel multifunctional polyamide composites produced by incorporation of AlTi sub-microparticles

The potential of using of sub-microalumina/titanium particles as a reinforcement that can produce multifunctional polymer composites was explored. Novel multifunctional composites have been developed by incorporating sub-micro-alumina/titanium particles into polyamide6. The composites were investigated for their thermal, viscoelastic, water uptake and mechanical properties, as a function of alumina/titanium concentration. A detailed study of the morphological observation by scanning electron microscope was used to correlate the microstructures to the mechanical properties. Flexural testing shows that the flexural modulus and strength of the composite are improved by 22%, and 15%, respectively, with incorporating 10 wt% alumina/titanium. In addition, the impact strength was improved by about 19%. Furthermore, 10 wt% alumina/titanium increases the interfacial shear strength of polyamide6 by about 23%.