Preparation and characterization of polyurethanes/allyl novolac resin simultaneous interpenetrating network

Abstract A series of interpenetrating networks (IPNs) of polyurethanes (PU) and allyl novolac resin were successfully prepared by mixing all the essential components at the same time so that these two polymer networks were constructed simultaneously. The major components included PU prepolymers and allyl novolac resin. The former components were prepared by reacting 4,4′-diphenyl methane diisocyanate (MDI) with poly (tetramethylene oxide) (PTMO) whose molecular weight range falls in 600–700 (for convenience this polymer is called as UT1), 900–1050 (UT2) and 1900–2100 (UT3) separately, and the latter component was synthesized by substituting the hydroxy group of phenolic resin with allyl group. The phenomena of phase mixing for these IPN polymers were investigated and confirmed through dynamic mechanical analysis (DMA), differential scanning calorimetric analysis (DSC) and transmission electric microscopy (TEM) analysis. The tensile strength of these IPNs was improved and was in accordance well with their structures, viscoelastic properties and morphology.