The Effect Of Surfactant On Rigid Polyurethane Foaming Process With Carbon Dioxide As Physical Blowing Agent

Rigid polyurethane (PU) foams are widely used as heat preservation materials because of their excellent thermal insulation property. Reaction and foaming process happens simultaneously in PU foams preparation, and generally, the addition of surfactant can adjust and control the cellular structure. Carbon dioxide (CO2), as a new physical blowing agent, has the advantages of non-toxic and low price. Polyether polyol R090and polymethylene polyphenyl isocyanate PM-200as raw materials, bis(2-dimethylaminoethyl)methylamine as catalyst, the influence of8kinds of surfactants (B8474、L6900、SD61、B8525、B8534、 AK8832、TN1058and TN1078) on CO2foaming PU process has been studied. The results show that:the PU foamed by CO2has smaller cell diameter and larger cell density than that of PU foamed by water. Though the existence of surfactant can reduce the surface tension of R090/CO2system obviously, different surfactants has little difference. The CO2solubility in R090with different surfactants is almost same. At6MPa, the sequence of CO2diffusion coefficients in R090with different surfactants is R090+B8474> R090> R090+B8534> R090+TN1078.In the period of cell nucleation, lower surface tension can increase the cell nucleation, and in the period of cell growth, different diffusion coefficient may change the cell size. Furthermore, the CO2saturation time will affect the amount of CO2in R090, and the reaction time will change polymer viscosity, so that, both the saturation time and reaction time have significant impact on the morphology of PU foam.