THE USE OF PENTANES AS BLOWING AGENT IN RIGID POLYURETHANE FOAM FOR LAMINATION

Pentanes tend to be considered as long-term alternative blowing agents for rigid polyurethane foams. They are environmentally friendly, non- toxic and economically feasible. A major drawback of the use of pentan es is their flammability and their relatively high thermal conductivit y, compared to CFC-11. As pentane processing techniques have improved considerably, safety can now be insured at a reasonable price. In this paper the overall performance of pentane blow laminates in terms of p rocessing, insulation value, mechanical properties and flammability is demonstrated. The ageing characteristics are compared to those of CFC -11 blown foams. The low vapour pressure of both n-pentane and cyclope ntane is shown to induce condensation effects. The consequences of con densation in terms of thermal conductivity and dimensional stability a re discussed. The problem of pentane solubility in the polymer matrix and its influence on the long-term foam performance is addressed. Poss ible solutions are presented.