A new weatherability test method for coatings has been developed. The method is a cyclic treatment of A; 2h UV irradiation in 3wt % aqueous hydrogen peroxide solution at 40°C and B; 20h UV irradiation in 0.8 atm oxygen and 0.2 atm water vapor at 80°C.UV fluorescence lamp and metal halide lamp were employed for treatment A and B, respectively. Four alkyd/melamine type coatings containing titanium oxide pigment were subjected to treatment A, B, the cyclic test, and outdoor exposure in Okinawa. The treatment A produces small pits around titanium oxide pigment near the coatings surface. The pits are shaped by loss of resin around the pigment caused by photo-catalysis oxidation. The treatment B yields small waviness on the coatings surface. The waviness is formed by resin shrinkage caused by hydrolysis and oxidation. The cyclic treatment of A and B reproduces gloss loss and surface morphology of outdoor-exposed coatings in 100 times, acceleration.
In this study, the light stabilizer having HALS on PE chain-end (PE-TMPM) was prepared using various catalysts. Because PE chain of PE-TMPM is incorporated into the crystalline part, it seems that the compatibility of HALS progress. The presence of TMPM in the PE-TMPM obtained with V (acac) 3 (acac=acetylacetonate) /Al (C2H5) 2C1 catalyst system was confirmed by IR and 13C NMR measurements, and that in the PE-TMPM with other catalyst systems was not detected, indicating that V (acac) 3/Al (C2H5) 2Cl catalyst system was the most suitable for the synthesis of PE-TMPM. The light stability of the PE/PE-TMPM blend was found to be higher than that of PE/TMPM blend. In particular, the tendency was strongly exhibited in longer irradiation time, suggesting that the incorporation of PE chain caused TMPM a certain decreasing in volatility.
Thermo-oxidized ethylene-propylene-dinen (EPDM) rubbers (sulfur vulcanized) were charac terized by FT-IR spectroscopy and high-resolution pyrolysis-gas chromatography-mass spectro metry (Py-GC/MS). Depth profile of micro FT-IR spectra indicated that carbonyl products were formed more abundantly in the surface area. In addition, saturated and unsaturated carbonyl products formed in the polymer chain were typically observed in the ATR FT-IR spectra. On the basis of the observed spectra, the formation mechanisms of the carbonyl products were discussed. Moreover, it was proved that diene unit was oxidized earlier to yield 5-acetylcyclopentadiene (ACP) which was confirmed by observing the MS spectrum obtained by Py-GC/MS. Finally thermo oxidation mechanism of sulfur vulcanized EPDM was comprehensively discussed.