Abstract: A phenolic foam having a density of from 10 kg/m3 to 100 kg/m3 and comprising a phenolic resin base part and a cellular part most of which is made up of a large number of fine cells, wherein the fine cells contain a hydrocarbon and have an average cell diameter of 5 &mgr;m to 200 &mgr;m, and the cell walls of at least most of the fine cells are formed of a smooth surface of the phenolic resin base. While the blowing agent is a hydrocarbon, the foam has a thermal conductivity comparable to that of a conventional foam made with a flon blowing agent, undergoes no change in thermal conductivity with time, exhibits excellent mechanical strength such as compressive strength, and has reduced brittleness.

Abstract: A novel styrene type resin having excellent strength which comprises(A) a unit represented by the formula ##STR1## wherein l and n are each an integer of 1 to 20;m is an integer 0 to 5; andR.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a cyclohexyl group or a phenyl groupand(B) a unit represented by the formula ##STR2## wherein R.sub.1 is a hydrogen atom or a methyl group andR.sub.2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atomsand wherein the ratio of S.sub.A (namely, an amount of structural unit (A)) to S.sub.B (namely, an amount of structural unit (B)), S.sub.A /S.sub.B, is in the range of 0.00001 to 0.006; the resin having weight average molecular weight in the range of 200,000 to 600,000; and a total amount of styrene type monomers, styrene type dimers, styrene type trimers and a solvent of not more than 0.8% by weight.