THE THERMAL-STABILITY OF RIGID POLYURETHANE FOAM IN INSULATING PIPES

The rigid polyurethane, PUR, foam was prepared by reacting diphenylmethane diisocyanate, MDI, with aliphatic correactants of polyether type. The insulating pipe was made by moulding technic. The PUR pipe was subjected to isothermal aging by special equipment which was constructed for this purpose in order to study the structural changes in PUR foam under various temperatures and to define the maximal temperature at which it might be used as insulation in insulating pipes. The structural changes of PUR foam were studied by means of spectrophoto‐metric measurement and thermal analysis. The evidence of thermal degradation of PUR foam has been found. Its course and intensity depend upon the temperature and differ throught the verticale cross‐section of the insulating pipe. The correlation between chemical changes of PUR foam and its physical properties are also discussed. © 1990 Hüthig & Wepf Verlag, Basel