Katsuya Ito

Dispersion of Nano TiO2 in Ethylene Glycol and Poly(ethylene terephthalate)

Nano TiO2 was dispersed in ethylene glycol (EG) by the replacement of dispersion medium from water sol. EG/TiO2 suspension was well stabilized by the electrostatic repulsive force when pH value of suspension was less than 4.3. In situ polymerization starting from bis(2-hydroxyethyl) terephthalate (BHET) and EG/TiO2 suspension was carried out to prepare a series of poly(ethylene terephthalate) (PET)/TiO2 nanocomposites. Under highly acidic conditions, 97% particles dispersed in PET matrix had the size less than 100 nm. With the increase of pH value, aggregation occurred and larger size particles appeared. A tensile test showed that Youngs modulus of PET was increased by the addition of nano TiO2

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.

Surface Structural Development of Polyester Film having Incompatible Polymers

This study is concerned with the analysis of relationship between surface structure and the micro voids that are formed by stretching the composite polymer sheet having incompatible polymer particles. Now we tried to simulate the void formation near surface and surface structure considering the interfacial delamination between Poly (ethylene terephthalate) (PET) and dispersed incompatible polymers, and to compare the numerical results by finite element method (FEM) with experimental ones. The following results were obtained; (1) Decreasing interfacial tension coincided with increasing the height of protrusion that was formed by stretching experimentally. Also the critical stress of delamination coincided with increasing the height numerically. (2) Increasing interfacial tension or decreasing the critical stress of delamination coincided with enlarging the aspect ratio of the void near surface. These results are similar to the result of study that was intended for the inside of void expression. (3) It is supposed that a basin would be expressed on surface with void expression from the experimental and numerical results quantitatively.