Development of fluororubber foam by supercritical N-2 foaming through irradiation pre-crosslinking and secondary cross-linking

The preparation of fluororubber foam has always been a promising task because of its easy shrinkage characteristic, a promising way to overcome this challenge is to implement collaborative technology. Fluororubber foam with stable properties were successfully developed by irradiation pre-crosslinking, followed by supercritical foaming and secondary cross-linking in the oven using supercritical N-2 as foaming agent. The cross-linking degree and tensile modulus of fluororubber foam enhanced with the increased absorbed dose (40, 50, and 70 kGy), and the second cross-linking effect was better at the dose of 40 kGy in fluororubber foam. The fluororubber foam without secondary cross-linking would shrink gradually, however it could reach a stable state after secondary cross-linking. Fluororubber filled with carbon black (5, 10, 15, and 20 phr) showed different modulus change trend in different strain range. Better fluororubber foam was obtained after secondary crosslinking, where the addition of carbon black promoted the fluororubber foams with more uniform cell structure. The secondary cross-linking had a good stabilizing effect on fluororubber foam filled with carbon black, which had an important guiding significance in practical production.