Petroleum resin is different from other thermosetting compounds in that it does not release low molecular compounds during the curing process, and has high condensation in the liquid state. Curing time is carried out by direct addition, which is very small for an unmodified system. Generally around 2%, which means that the molecular exclusion is very small.
The petroleum resin was cast in the standard mold, the volume of the standard mold cavity and the volume of the sample were measured, and the volume reduction rate of the sample was calculated.Experimental method: disassemble the casting mold and take out the molded resin sample, and then use the caliper to accurately measure the cavity size (including length, width, and height) of the casting mold to 0.01 mm. Hang the resin sample on the balance with copper wire or hair, and weigh its weight in the air. Then put the sample into 20 distilled water, and weigh its weight in the water. The weighing accuracy is up to 0.001g.