From insulate + -ive.
insulative (comparative more insulative, superlative most insulative)
- Serving to insulate
1973, The United States Patents Quarterly - Volume 178[1], page 267:Housed resistors have their wire- wound cores embedded in an insulative material which is enclosed within the housing.
1995, Electrical Overstress Electrostatic Discharge Symposium, Proceedings: 1995[2], →ISBN:The charge, that is applied and results in the measured voltage, may or may not pass through the insulative layer to the metallized film.
2012, Niels Jonassen, Electrostatics[3], →ISBN, page 132:And although charged insulated conductors do appear in many practical, industrial as well as everyday, situations, there is no doubt that charged insulative materials are far more common.