外装用塗装鋼板は, 紫外線や熱などによる塗膜の劣化と水, 塩分および湿潤乾燥の繰り返しなどによる鋼板の腐食が交互に複合的に進行して劣化していく. それと同様の劣化環境を与えるために, 塩水噴霧メタルハライドランプでの紫外線照射などの各モードを連続的に行える新規複合サイクル試験機を考案・製作した. 次にその試験機を用いて, 暴露実績の有る5種類の塩ビ鋼板について複合サイクル試験を実施し, 屋外暴露回収品を含めて外観観察および種々の物性評価を行ったその結果, 塩水噴霧2時間一紫外線照射16時間一湿潤2時間の試験条件で複合サイクル試験を行うことにより, 屋外暴露に比較的近い劣化を再現することがわかった. また評価項目としては, 外観観察, 色差, 光沢, 塗膜剥離強度が適切と考えられる.

抄録全体を表示

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.

抄録全体を表示

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.

抄録全体を表示