Secondly, cell interpenetration engendered during bubble phase is the micro crack of the foam and acted as defects of the material.

• 2.；聚氨酯硬泡发泡过程中形成的泡孔互穿是材料断裂微裂纹的形核地点，材料的断裂基本属于脆性断裂，但是也有部分的韧性断裂。