The deterioration of the coated steels is defined as the combing and synergistic effects of the degradation of surface coating film by ultraviolet ray and heat, and the corrosion of underneath steels by water and salt. For the evaluation of the deterioration process of the coated steels, the cyclic-weathering test apparatus was newly designed combining salt spray, ultraviolet ray irradiation of metal-halide lamp and conditioning under a moisture atmosphere. Five types of polyvinyl chloride-resin coated steels were weathered to the cyclic-weathering in the test apparatus, and the surface appearances and the changes of some properties were measured for comparison with those of the outdoor exposed samples. The cyclic test combining salt spray for 2 hours, ultraviolet ray irradiation of metal-halide lamp for 16 hours and conditioning under moisture for 2 hours was shown to cause the deterioration of the coated steels highly similar to those of outdoor exposed ones. Moreover, it was recognized that appearance, color difference, gloss and adhesive strength are relevant to the evaluation of the deterioration of coated steels.
Silicone rubber is known as a material that carries variety of excellent properties such as high heat resistance and flavorless nature. Moreover, because silicone rubber also carries odorless nature, thus it is widely used in the production plant and industrial equipment of beverage or food. Typical examples of industrial equipment include beverage dispenser and cup-type vending machine, where the silicone rubber is often used as tube or gasket in the hot drink flow. Silicone rubber tube for beverage as mentioned above is mostly manufactured by processes including mastication, hot air vulcanization, postcure or boiling water immersion. In recent years, the platinum vulcanized silicone rubber has become one of the main processing methods instead of the organic-peroxide vulcanization due to the urge of taste improvement. However, it was understood that the rate of addition reaction is generally slower in the platinum vulcanization rather than organic peroxide. Thus the authors re-conducted experiments for reviewing conditions for the hot air vulcanization and different postcure parameters. The results clearly indicated various improvements in general physical property, heat resistance, and adhesion level to stainless steel of platinum vulcanized silicone rubber.
Kenaf bast fiber was used to prepare the composite composed of kenaf fiber and linear low density polyethylene (LLDPE). The thermal stabilities of kenaf fiber and kenaf fiber/LLDPE composite were investigated using thermogra vimetric analysis (TGA) in nitrogen and air atmosphere. The result obtained in inert condition showed that kenaf fiber has lower thermal stability than pure LLDPE and kenaf fiber/LLDPE composite. On the other hand, thermooxidative de gradation of them revealed that kenaf fiber/LLDPE composite has higher thermal stability than pure LLDPE beyond 400°C, indicating kenaf fiber has antioxidant effect for LLDPE.