Hiromasa Adachi

Cell distributions in and sound absorption characteristics of flexible polyurethane foams

In this article, the two-dimensional distributions of cells from the cross section of some flexible polyurethane foams were cleared, and the three-dimensional distributions of cells based on Saltykovs theory were estimated further. As a result, it was found that a mean of the two-dimensional distributions of cells was a good linear relation with a mean of the three-dimensional distributions of cells, and it was confirmed that cell structure of the foams which should have been analyzed in the three-dimensional distributions was evaluated by analysis of the two-dimensional distributions fully. It was also found that not only cell number but also cell distribution was necessary in the evaluation of flexible polyurethane foams, and cell diameter was closely related to the sound absorption coefficient in polyester-based flexible polyurethane foams.

Compression Modulus of Open-Celled Polyethylene Foams.

連続気泡ポリエチレンフォームについて, 圧縮モードにおける動的粘弾性測定から求めた動的弾性率と静的圧縮試験から求めた静的弾性率とを比較した. 動的弾性率が静的弾性率と正の相関関係にあり, 特に圧縮ひずみ50%における動的弾性率と静的弾性率とは正の直線関係にあった. 動的弾性率は静的弾性率より大きいが, スケルトンが多く座屈していてクリープ変形が起こりやすくなっていることが原因であると考えられる. また, 連続気泡ポリエチレンフォームの基材と空孔率からフォームの圧縮弾性率を推定する方法について検討したところ, 空孔率が大きいフォーム試料の場合において, 静的弾性率の実験値は飯塚らの斜めセルの曲げ変形のみを考慮した式に正六角形空孔の角度30°より幾分小さいθ=15°～24°を代入した計算値の範囲にあった.