STUDIES ON CROSS-LINKING OF A LIQUID POLYCARBOSILANE INITIATED BY 2, 2′–AZOBISISOBUTYRONITRILE

Cross-linking reaction of a hyperbranched liquid polycarbosilane (HBPCS) initiated by 2, 2′–azobisisobutyronitrile (AIBN) was studied at an inert atmosphere. The influences of temperature, AIBN amount and time on the cross-linking reaction and ceramic yield of HBPCS were investigated. The cross-linking reaction can be improved at a higher temperature. The increase of the amount of AIBN added is beneficial to promote the cross-linking, while the ceramic yield increases first and then remains stable with the increase of AIBN addition. The optimal range of mass fractions (the same below) of AIBN added to HBPCS is 1.0%–2.0%. With the increase of cross-linking time, the degree of cross-linking and ceramic yield of HBPCS increases first and then remains constant. The ceramic yield of cross-linked HBPCS with 1.5% AIBN at 80 ℃ for 6 h reaches above 75% up to 1 000 ℃. In addition, the phase composition of the HBPCS-derived ceramics was characterized. It was found that the introduction of AIBN significantly retards the crystallization of β-SiC.