Abstract
An efficient way to improve the low ceramic yield and poor processability of PMS as a SiC precursor utilizing high levels of Is–H, was developed by simply modifying at 70 °C for 1 to ∼3 h in presence of 1 wt.% borazine. The ceramic yield was significantly enhanced from 35 to 87 wt.% and molecular weight increased from 740 to 3554. It is believed that these benefits are due to dehydrocoupling of Si–H of the PMS with N–H of the borazine to form Si–N units, and of Si–H with itself to form Si–(Me Si)Si 2 units. The structure evolution of the PMS during treatment was thoroughly studied using TGA, GPC, 29Si CP/MAS-NMR, 1H-NMR, IR and GC-MS. Furthermore, the processability of the PMS was improved controllable by alteration either the content of borazine added or heating time. Green fibers were readily prepared by hand-drawing the improved PMS solution; these were characterized by SEM.
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