Structures and physical properties of rigid polyurethane foams with water as the sole blowing agent

• 作 者: LI Xiaobin CAO Hongbin ZHANG Y
• 机 构: Institute of Process Engineering,Graduate School of the Chinese Academy of Sciences
• 出 处: 中国科学B辑
• 发表日期: 2004年期
• 关键词: polyether polyol polyurethane rigid foam compressive strength dimensional stabil
• 基金项目: 中国科学院基金;The authors would like to thank kind Yuping Li for carrying out FT-IR measurements

Rigid polyurethane foams blown by varying water level were prepared in this study. The structures and physical properties of rigid polyurethane foams blown by water were measured with FT-IR, universal testing machine (Instron3365), scanning electron microscope (SEM) and differential scanning calorimeter (DSC). The results show that polyurea and polybiuret were the typical characteristics, and the cream time and gel time were shorter for the fully water blown rigid foams than that for the fully cyclopentane blown foams. The density of foam samples decreased from 45.0 kg/m3 to 27.4 kg/m3 with the increase of water level from 3 pph to 7 pph. Compressive strength exhibited the similar behavior with density. The average cell size of foam samples ranged from 241цm to 356цm with the increase of water level from 3 pph to 7 pph, respectively. At the same time, poorer dimensional stability was encountered with the increase of average cell size due to fast diffusion rate of CO2 out of the foam. The results of thermal analysis show that the glass transition temperature (Tg) shifted to a higher temperature with the increase of isocyanate level when more water was used as chemical blowing agent.