▎ 摘　　要

NOVELTY - Preparing a long-chain cured epoxy/graphene composite film involves uniformly dispersing graphene in acetone, and uniformly mixing by ultrasonic vibration at 10-30 degrees C to obtain a uniformly dispersed graphene suspension. The amount of acetone is an amount capable of sufficiently dispersing graphene. The epoxy resin in acetone is dissolved and stirred uniformly to obtain an epoxy resin acetone solution. The amount of acetone is an amount capable of sufficiently dissolving the epoxy resin. The reaction solution is prepared by mixing the graphene suspension and the epoxy resin acetone solution, and uniformly mixing by ultrasonication to obtain a reaction solution, where volume ratio of graphene and sum of graphene and epoxy resin is 1.25-5 wt.%. The solvent is removed into the reaction solution, added J2000 long-chain curing agent, stirred the ultrasonic to remove the acetone to obtain a mixture. USE - Method for preparing long-chain cured epoxy/graphene composite film. ADVANTAGE - The method enables to prepare long-chain cured epoxy/graphene composite film is effectively improves flexibility, conductivity and sensing performance of flexible strain sensors. DETAILED DESCRIPTION - Preparing a long-chain cured epoxy/graphene composite film involves uniformly dispersing graphene in acetone, and uniformly mixing by ultrasonic vibration at 10-30 degrees C to obtain a uniformly dispersed graphene suspension. The amount of acetone is an amount capable of sufficiently dispersing graphene. The epoxy resin in acetone is dissolved and stirred uniformly to obtain an epoxy resin acetone solution. The amount of acetone is an amount capable of sufficiently dissolving the epoxy resin. The reaction solution is prepared by mixing the graphene suspension and the epoxy resin acetone solution, and uniformly mixing by ultrasonication to obtain a reaction solution, where volume ratio of graphene and sum of graphene and epoxy resin is 1.25-5 wt.%. The solvent is removed into the reaction solution, added J2000 long-chain curing agent, stirred the ultrasonic to remove the acetone to obtain a mixture. The mass ratio of J2000 long-chain curing agent and epoxy resin is 3:1. The mixture is poured into a mold and cured to obtain a long-chain cured epoxy/graphene composite film. An INDEPENDENT CLAIM is included for a flexible strain sensor, which comprises long chain cured epoxy/graphene composite film, and has a conductivity of greater than or equal to 10-6 siemens per centimeter and a strain sensitivity coefficient of 3-15.