Katsuhisa Yamashita

The role of the dye/iron arene complex/amine system as a photoinitiator for photopolymerization reactions

Abstract New three-component photoinitiator systems consisting of a dye, an iron arene complex, and a phenylglycine derivative were investigated through polymerization activity measurements, fluorescence quenching experiments and time-resolved absorption spectroscopy. The efficiency of this three-component (e.g. dye 2/CPG/Complex 1) system in radical polymerization reactions is higher by a factor of three to four than that of two-component systems (e.g. dye 2/CPG). The first step of the photoreaction occurs between the dye and the iron arene complex. An iron arene complex reacts with the singlet excited state or the triplet state of a dye depending upon the nature of the dye used (dye 1 or dye 2). Also, energy transfer occurs in these systems. Finally, the amine derivative reacts with the excited iron arene complex formed after reaction with the excited dye.

Visible light‐induced polymerization reactions: The seven‐role of the electron transfer process in the dye/iron arene complex/amine system

A new three component photoinitiator system consisting of a dye, an iron arene complex, and a phenylglycine derivative was investigated by fluorescence quenching experiments and laser flash photolysis. The efficiency of a three-component system in photopolymerization reactions is higher by a two-fold factor compared to that of the two-component system. The first step of the photoreaction occurs between the dye and the iron arene complex. The iron arene complex reacts either with the singlet excited dye or with the triplet excited dye according to the nature of the dye. An electron transfer occurs in these systems. The mechanism was discussed in terms of the absence of the formation of a terminating radical in the three-component system.

Modeling of Cell Structure in Polyurethane Foam

We suggested that the cell structure of polyurethane foam could be approximated to be oval by the use of the finite element method. Three kinds of parameters for cell modeling were employed, which are the ratio of radius, the area, and the thickness of the cell wall.

Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey’s equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society pub...

Numerical analysis of neck propagation in polymeric materials. Part 2 – Neck propagation behaviour of poly (butylene terephthalate) mouldings

Abstract This paper examines the factors controlling the formation and propagation of a neck in poly (butylene terephthalate) (PBT) mouldings under tensile loading. Tensile tests were used to investigate the load–displacement and deformation behaviour of PBT and the accompanying changes in surface temperature. In parallel with this experimental study, a numerical model was developed for the deformation of PBT mouldings and neck formation under tensile loading analysed using finite element analysis (FEA). The calculated numerical results were compared with the experimental data. This work has shown that formation does not occur in PBT immediately after the yield point. Instead, plastic deformation first progresses homogeneously through the testpiece. Neck formation and propagation, accompanied by a rise in temperature, then follow. The load–displacement behaviour calculated using FEA could be approximated to the experimental data by adapting an elastic–plastic model at a stable temperature to the necking behaviour of PBT moulding. Furthermore, the dependence of neck formation on strain rate is related to the plastic instability, as demonstrated by the numerical results, and does not depend upon heating effects.

Analysis of interfacial delamination in stretched PET film containing incompatible polymer particles Mechanism of void formation

Abstract The processing behaviour of poly(ethylene terephthalate) (PET) films containing incompatible polymeric particles has been analysed, with particular reference to the relationship between the particle-matrix interfacial energy and the microvoids that are formed when the composite film is stretched at 90°C. A model was developed to simulate void formation due to interfacial delamination between PET and three types of dispersed incompatible polymer: poly(4-methyl pent-1-ene) (TPX); polypropylene (PP); and polystyrene (PS). Numerical results obtained using the finite element method were compared with experimental data on blends with different particle sizes,for both the internal and sub-surface regions. Experimental measurements showed that increasing the difference in surface energy between PET and the added incompatible polymer is associated with the formation of larger voids. Modelling studies showed that increasing the interfacial energy between the two components of the blend causes a decrease in the critical stress for delamination. Interfacial tension values obtained from the literature 1 related qualitatively to the critical stress for void formation calculated using numerical analysis. Numerical analysis predicted a tendency to form depressions on the surface of the film near sub-surface voids, which was confirmed quantitatively by experiment.

Measurement of fiber orientation distribution in injection-molded composites with high filler content

Short-fiber-reinforced composites are widely used in a number of industries and applications, including in the transportation industry, and in business machine, durable consumer items, and sporting goods. Properties of fiber-reinforced composite depend on its fiber orientation distribution. Thus, knowing the fiber orientation is of great importance, and a number of researchers have been interested in developing useful and accurate techniques for determining the fiber orientation in injection-molded parts formed from short-fiber composite. However, out-of-plane orientation was preformed manually and difficulties arise when employing the technique in the case of composites with high fiber contents, over 50wt.%. In this research, short-glass fiber-reinforced polyamide 6 specimens produced using two different plate-shaped cavities having three different thicknesses ranging from 2mm to 4mm and with the fiber contents ranging from 30wt.% to 65wt.% are carried out using injection molding. The three-dimensional (...

Advanced fiber orientation prediction for high filler content short-fiber/thermoplastic composites

Properties of fiber-reinforced composite are dominated by the microstructure of the fabricated part rather than the properties of constituent materials. As the microstructure of composite is related to the flow-processing route of the fiber-reinforced suspensions and the geometry of the mold, the microstructure of composite can be tailored in order to achieving high-performance composites by exercising control over the flow processing. Thus, numerical methods are used to model the resin flow, the fiber orientation, and mold design, and they become important challenges during molding process. In our previous research, a theoretical fiber-fiber interaction model with a global fiber interaction coefficient was developed. In this study, the three-dimensional (3D) fiber orientation distribution is predicted by combining our developed fiber interaction model and improved Anisotropic Rotary Diffusion - Retarding Principle Rate (iARD-RPR) model. The fiber orientation calculation started from the gate, and from a ...

Numerical simulation of fiber interaction in short-fiber injection-molded composite using different cavity geometries

The theoretical fiber-interaction model for calculating the fiber orientation in the injection molded short fiber/thermoplastic composite parts was proposed. The proposed model included the fiber dynamics simulation in order to obtain an equation of the global interaction coefficient and accurate estimate of the fiber interacts at all orientation states. The steps to derive the equation for this coefficient in short fiber suspension as a function of the fiber aspect ratio, volume fraction and general shear rate are delineated. Simultaneously, the high-resolution 3D X-ray computed tomography system XVA-160α was used to observe fiber distribution of short-glass-fiber-reinforced polyamide specimens using different cavity geometries. The fiber orientation tensor components are then calculated. Experimental orientation measurements of short-glass-fiber-reinforced polyamide is used to check the ability of present theory for predicting orientation. The experiments and predictions show a quantitative agreement an...

On the Characteristic of the New Material Fender for Ship Collision

The new material fender that was made with TPE (Thermo Plastic Elastomer) is excellent in restoration, and it has good compression characteristic for energy absorber. We are doing the research that checks the characteristic of the new material fender for ship collision by the model test and numerical analysis. This report studied the characteristic of the new material fender for ships head-on collision by using the PEL-fender and urethane foam as the model. When rearranging the results, (1) When the entrance angle of the bow becomes large, the slope of a reaction force-bow penetration curve becomes steep. At this time, the change rate of the slope becomes steep with the increase of the entrance angle. Although reaction force differs as for PEL-fender and urethane foam, these trends resemble. (2) The reaction force of the dynamic test is bigger than the reaction force of the static test. (3) Absorbing effciency and energy absorbing factor do not change by the bow measure.