Provided is a composition comprising fluoroethylene and an epoxide having 6 or less carbon atoms.

Azeotropic or azeotrope-like compositions are disclosed. The azeotropic or azeotrope-like compositions are mixtures of E-1,1,1,4,4,4-hexafluoro-2-butene and ethylene oxide. Also disclosed are double azeotropic compositions of E-1,1,1,4,4,4-hexafluoro-2-butene and ethylene oxide. Also disclosed is a process of preparing a thermoplastic or thermoset foam by using such azeotropic or azeotrope-like compositions as blowing agents. Also disclosed is a process of producing refrigeration by using such azeotropic or azeotrope-like compositions. Also disclosed is a process of using such azeotropic or azeotrope-like compositions as solvents. Also disclosed is a process of producing an aerosol product by using such azeotropic or azeotrope-like compositions. Also disclosed is a process of using such azeotropic or azeotrope-like compositions as heat transfer media. Also disclosed is a process of extinguishing or suppressing a fire by using such azeotropic or azeotrope-like compositions. Also disclosed is a process of using such azeotropic or azeotrope-like compositions as dielectrics. Also disclosed is a method for sterilizing an article by using such azeotropic or azeotrope-like compositions.

A refrigerator oil composition used in a refrigerant containing one or more unsaturated fluorinated hydrocarbon compounds selected from compounds represented by the following general formula (1): C.sub.xF.sub.yH.sub.z (1), wherein x is an integer of 2 to 6, y is an integer of 1 to 11, z is an integer of 1 to 11, and there are one or more carbon-carbon unsaturated bonds in the molecule, the refrigerator oil composition containing a base oil (A) that includes polyvinyl ether, a modified silicone compound (B), and a specific epoxy compound (C).

A refrigerator oil composition used in a refrigerant containing one or more unsaturated fluorinated hydrocarbon compounds selected from compounds represented by the following general formula (1): C.sub.xF.sub.yH.sub.z (1), wherein x is an integer of 2 to 6, y is an integer of 1 to 11, z is an integer of 1 to 11, and there are one or more carbon-carbon unsaturated bonds in the molecule, the refrigerator oil composition containing a base oil (A) that includes polyvinyl ether, a modified silicone compound (B), and a specific epoxy compound (C).