A method simulating light degradation environment on the outdoor exposure test quantitatively has been studied. Based on this method, degradation environment, i, e, solar irradiance and surface temperature, on the exposure surface is calculated accurately with a statistical meteorological data, For the calculation, a model expressing the time dependant behavior of irradiance, surface temperature, and clouded condition are examined empirically based on the actually measured environmental data around the world. With this method quantitative degradation environment is able to be calculated easily and accurately without actual measurement that takes more than one year. Application of the quantitatively evaluated degradation environment for the durability design and durability estimation is highly expected.

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In order to develop the radiation resistant elastomers, the effect of the additives on the radiation induced degradation of the additives on the radiation induced degradation of EPR (EP11 and EPO7P) has been studied.
The additives used were Sumilizer GM and propyl floranthen, the former retards the cross-linking of elastomers and the later is an energy transfer agent. Irradiation was carried out by 2 MeV electron beam.Maximum dose was 11.36 MGy. Mechanical properties of samples were measured at room temperature.
Ultimate elongation decreases with increasing dose. When 5phr of both additives are blended together in EP11, the value of ultimate elongation is 40% at 10MGy. This compounding formula has the remarkable retarding effect for increase in Young's modulus by irradiation. The increasing rate of Young's modulus of the sample for dose is about one forth of that of EP11 which is blended 3phr of Sumilizer.
The relationship between the ultimate elongation (Eb) and Young's modulus (Y.M) of each sample is expressed by equation (1).
Eb∝ (Y.M) ^-α (1)
when α is found to be from 0.54 to 0.75.

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Chemiluminescence method was applied to evaluate the thermal oxidative stability of various polyolefins, namely high density polyethylene (HDPE), isotactic polypropylene (IPP), polybutene (PB) and poly-4-methylpentene (P4MP). The increasing order of the chemiluminescent intensity of the polyolefins coincided with that of oxygen uptake rate. The thermal oxidative stability of the polymers estimated by both chemiluminescence and oxygen uptake methods decreased in the following order : HDPE>> P4MP> IPP> PB. At an equivalent oxidation level the chemiluminescent intensity of HDPE was much lower than that of three other polymers providing tert-hydrogen in the polymer chains. On the basis of the results obtained the oxidation mechanism of HDPE was discussed.

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