Fujio Ohishi

Analysis of weathering of thermoplastic polyester elastomers-I. Polyether-polyester elastomers

Abstract Thermoplastic polyester elastomers (TPEE) are useful as new materials covering the region between rubbers and plastics. At present, the uses under outdoor conditions have increased. However, weatherability of TPEE is not clear. We have studied weathering of TPEE, by means of GPC, TG/DTA, FT-IR and 1 H-NMR and other methods. In conclusion, (1) Ether parts of the soft segment in the polymer are degraded selectively and ester bonds are formed. (2) In both outdoor exposure tests and the accelerated weathering test, main chain scission and crosslinking reactions occur. (3) There was a clear difference between tendencies of degradation by outdoor exposure and the accelerated weathering test. The amount of crosslinked products which formed during the accelerated weathering test was larger than that formed during the outdoor exposure tests.

Analysis of weathering of a thermoplastic polyester elastomer II. Factors affecting weathering of a polyether–polyester elastomer

Abstract To compare the contribution of degradative factors to weathering of a thermoplastic polyester elastomer (TPEE) photo-, thermal conditions and water were selected as the degradative factors. Experiments on photodegradation, thermal degradation and hydrolysis of TPEE were carried out. Spectral irradiation using sharp-cut filters with a xenon lamp, photodegradation under several temperature conditions and immersion in water during photoirradiation were also performed. The results of these experiments were compared with those of outdoor and accelerated weathering tests. The following conclusions were obtained under the experimental conditions: (1) a major factor of the degradation are ultraviolet rays below 310 nm; (2) an increase in temperature accelerates the rate of degradation reaction; and (3) the presence of water increases the amount of gel formation caused by cross-linking reaction.

Sensitive detection of degradation of modified poly(2,6-dimethyl-1,4-phenylene ether) by dynamic load thermomechanical analysis

Abstract Weathering of a modified poly(2,6-dimethyl-1,4-phenylene ether) (m-PPE) was studied. It was found that the glass transition temperature or the complex modulus of the exposed sample in bulky state was almost the same as that of the unexposed sample. SEC, IR and TG-FT IR measurements proved that only the surface region of the exposed sample degraded. We report the application of dynamic load thermomechanical analysis (DL-TMA) using compressive oscillating load to the analysis of surface degradation of m-PPE. The results from the DL-TMA method have close relation with the molecular weight of the surface region. It was proved that the surface degradation is detectable in the bulk state with high sensitivity by applying DL-TMA.

Formation of diamond nanoparticle thin films by electrophoretic deposition

Thin films of diamond nanoparticles were prepared by electrophoretic deposition (EPD) using 0.5 wt % dispersions in water, ethanol, and 2-propanol. The film growth rate increased with increasing voltage applied to the electrodes. However, an excessive increase in voltage caused the degradation of film morphology. The optimum voltage was 4 V with an electrode separation of 5 mm. The film growth rate was higher in organic solvents than in water. The deposited film had a smooth surface with an average surface roughness comparable to the size of primary particles of the source material. It is notable that the EPD films had a considerably higher physical stability than spin-coated and cast films. The stability was further improved by thermally annealing the films. IR analysis revealed that the diamond nanoparticles have carboxy and amino groups on their surfaces. It is considered that the stability of the EPD films originate from a chemical reaction between these functional groups.

Preparation of charge injection layer by electrophoresis of diamond nanoparticles

ABSTRACT Thin films of diamond nanoparticles were prepared by electrophoretic deposition in water dispersion. The voltage applied to the electrode of electrophoretic deposition gave a crucial influence on the film growth of nanoparticles, and a voltage of 3 to 4 V was found to be optimum for film formation. It was possible to obtain uniform coverage by the diamond nanoparticles on a substrate surface at an early stage of film growth without coagulation of the particles. By depositing a thin layer of diamond nanoparticles on a surface of aluminum cathode, electron injection from the cathode to tris(8-hydroxyquinolinato)aluminum was notably enhanced. It was suggested that electrophoretically deposited diamond nanoparticles can play a role of electron-injection layer to organic semiconductors.

WEATHERING ANALYSIS OF MODIFIED POLY (2,6-DIMETHYL-1,4-PHENYLENE ETHER) BY THERMAL ANALYSIS

ABSTRACT Weathering analysis of a modified poly (2,6-dimethyl-1,4-phenylene ether) using thermal analytical methods was studied. It was found that the evolution of CO2 and H2O was detected at the initial decomposition of degraded modified PPE. We report the application of dynamic load TMA (DL-TMA) using compressive oscillating stress to the analysis of surface degradation of plastics. The results from the DL-TMA method have close relation with the molecular weight of the region of the surface. It was proved that the surface degradation is detectable with high sensitivity without any pretreatment by applying DL-TMA.