A series of epoxy resin modified polyisocyanurate (EP-PIR) foams with oxazolidone (OX) ring and isocyanurate (IS) ring have been successfully prepared by the reaction of polymethylene polyphenylene isocyanate (PAPI) and diglycidyl ether of bisphenol-A (DGEBA). Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) are performed to investigate the influence of curing temperature on the chemical structure of EP-PIR foams. The glass transition temperatures of EP-PIR foam are in the range of 224-337 <sup>o</sup>C. The influence of the mole ratio of [PAPI]/[DGEBA] on the mechanical property, thermal stability and flame retardation has also been studied. The results indicated that the excellent thermostability of EP-PIR foams was due to the abundant highly thermostable isocyanurate ring and oxazolidone ring. UL94 results revealed that the foams with [PAPI]/[DGEBA] ratio above 2.5 could reach V-0 classification. With increasing the stoichiometry of [PAPI]/[DGEBA], the limiting oxygen index values increased linearly from 24.5 to 30.0 vol %. Scanning electron microscopy images of burned foams illustrated the flame-retardant mechanism was due to the excellent charring ability. Cone calorimeter tests showed that the peaks of heat release rate were always as low as 266.5 kW/m<sup>2</sup>. Moreover, highly thermostable isocyanurate ring played an important role in the suppression of smoke emission.

Preparation and properties of highly thermostable polyisocyanurate foams modified with epoxy resin

256th National Meeting (2018)

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