Ethynyl phenyl azo novolac foam (EPANF) was prepared by high temperature foaming.Structure of ethynyl phenyl azo novolac resin (EPAN) was characterized by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC).Optical microscopy

scanning electron microscopy (SEM)

thermal conductivity analyzer

critical oxygen index analyzer and thermal analysis (TG) were used to examine the morphology

compression strength

thermal insulation

flame retardant and thermal properties

respectively.With 18% of blowing agent and apparent density of 0.179 g/cm3

fine and uniform morphology was obtained for EPAN sample of average diameter around 350μm.Among those properties

compressive strength

coefficient of thermal conductivity and critical oxygen index (which is an indication of flame retardation) were proportional to apparent density of EPANF.As apparent density of 0.363 g/cm3

compression strength was up to 5.63 MPa.However

heat insulation performance was decreased slightly with the increase of apparent density.TG showed that there were two exothermal reactions with mass losses of 5% and 10% that occurred at 333 and 381℃

respectively.Char yields at 700 and 1000℃were measured to be 65.8% and 58.2%

respectively.There are significant improvements in both heat and ablation resistance compared with the use of ordinary novolac phenolic resin.As a potential thermal structure and ablative resistant material

EPANF was expected to find wide applications in aerospace and related fields.