This study is concerned with the mechanical properties in the vertical direction of the ozone-deteriorated nitrile rubber (NBR). NBR was sliced from the surface by a microtome. The crack behavior and mechanical properties were investigated as a function of depth, time and ozone concentration. Mechanical properties discussed in this study are tensile strength, tensile modulus of elasticity and elongation at break. There is a proportional relationship between the extent of deterioration and mechanical properties as
σ = (21.3c+1.70) logt · logd + 14.5 ± 2.90,
where a is tensile strength (Mpa), c is ozone concentration (ppm), t is exposure time (hr) and d is depth (mm) from the surface. If the ozone concentration was known, it is possible to estimate the time that the destruction occurs at a given depth from the surface. The crack increased significantly with the increase of ozone concentration. However, it was observed from the surface observation and the surface analysis by ESCA that the strength decreased only on a very thin surface.

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The property of diacylhydrazine (DHZ) as a crystal nucleating agent for polypropylene (PP) was studied by differential scanning calorimeter (DSC) by measuring the effect of additives on the crystallization temperature (Tc) of PP. Aromatic, aliphatic and mixed-type DHZ were synthesized and used as an additive. The nucleating activity of a DHZ was defined as the rise in Tc by its addition. From the Tc values observed, the eighteen DHZ's studied were classified into three groups;
(a) DHZ's with thermally stable activity, (b) inactive DHZ's, and (c) DHZ's with thermally unstable activity.

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The glycidyl ester type epoxy resin for the molding was exposed in outdoor for 2 years. As time shortening exposure condition in proportion to the outdoor exposure, the exposure to strong energy xenon-arc accelerated test was carried out for 5000 hours. Surface erosion depth, glossiness, surface roughness and contact angle were measured in order to evaluate the degree of the degradation, and the surface of the samples were observed by using SEM. The article concludes as follows. The glycidyl ester type has more excellent weatherability than epi-bis epoxy type. However, the difference between samples is not significant in electrical characteristics such as tracking resistance and reliability for the ark. The xenon exposure 412 hours found to be corresponding to the outdoor exposure 1 year by the measurement of the total energy of light. From the degradation behavior of glossiness and surface roughness, the outdoor exposure 1 year is correspondent to xenon exposure 500 hours. The outdoor exposure of 2 years has the almost the same effects in xenon exposure of 1000 hours. However, time shortening test by the xenon exposure is difficult on the viewpoint of the changes of erosion depth and contact angle.

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