摘要
以三聚氰胺和甲醛为主要原料制备了开孔和闭孔热固性泡沫。考察了预聚体黏度、固化剂含量、微波加热时间、发泡剂含量和表面活性剂含量对泡体密度和泡孔结构的影响。结果表明:该热固性树脂在弱碱液中预聚而在弱酸液中缩聚进而交联固化,发泡前期的黏度小以便成泡,后期的黏度较高以防塌泡;泡沫开孔的条件是发泡时液膜黏度高而弹性低,有足够弹性的液膜就可以得到闭孔泡沫;随着甲酸含量增大,形成泡体的密度先减小后增大。微波可实现瞬时均匀加热,形成闭孔发泡体的最佳辐照时间比开孔的短;适度增加发泡剂会提高发泡率而降低其密度;乳化剂浓度增加,薄壁大泡孔中间形成更多厚壁小泡孔,薄壁大泡孔承压能力低,联络的厚壁小泡孔回弹性好。
Open-cell and closed-cell thermoset foams were synthesized and prepared using melamine and formaldehyde as raw materials. The effects of resin viscosity, radiation time and the amounts of formic acid, n-Pentane and OP emulsifier on foam density and foam structure were discussed. It was shown that thermoset resins reacted into oligomers in weak alkali while they crosslinked in weak acid. Lower viscosity was fitful for foaming in early stage while higher viscosity prevented foam broking or even collapsing in late stage. Open-cell foam was formed from resin film with higher viscosity and lower elasticity. Closed-cell foam was formed from resin film with sufficient elasticity. The foam density decreased first and then increased with more acid. Microwave radiation evenly heated the resin foam regardless of shorter optimal radiation time for closed-cell-foaming against open-cell-foaming. Higher concentration of foaming agent was good for lower density. OP emulsifier caused larger foams among thicker small foams in which thin foam film was capable of resisting lower compression while thicker film became more resilient.
出处
《塑料》
CAS
CSCD
北大核心
2015年第5期14-17,共4页
Plastics
关键词
三聚氰胺甲醛泡沫
交联
黏度
密度
微波
melamine formaldehyde foam
crosslinking
viscosity
density
microwave
