Highly crystalline polyisoxazoline and polyisoxazole were synthesized via addition condensation polymerization by the reactions of terephthalohydroxamoyl chloride （TPHC） with diolefins in a non-polar solvent. And the physical properties of the produced polymers were clarified. The electrical properties of polyisoxazoline, polyisoxazole, and their molding compounds with epoxy resin were investigated on the basis of physical properties of the polymers. The following results were obtained:
（1） Polyisoxazoline (I-A) (ρ_28℃=10⁹Ω·㎝), the reaction product of TPHC with m-phenylenedimaleimide, and (II-A) (ρ_29℃=10⁵Ω·㎝) from the reaction of TPHC with ethylenebisacrylamide have shown the semiconductive characters.
（2） Polyisoxazole (III-A), the reaction product of TPHC with 1, 4-diethynylbenzene, has shown characteristics of a positive thermistor.
（3） I-A, II-A-, and III-A-Epon 828 molded compounds, cured with ethylenediamine at room temperature, have shown small electrical energy losses.
（4） 10 %-I-A- -II-A- and -III-A-Epon 828 molded compounds were found to be very thermally sensitive resistors in the temperature range of 25-90 ℃. These newly molded compounds from heterocyclic polymers, such as polyisoxazoline and polyisoxazole, were found to have the characteristics of the thermistors.