A series of spinnable polyaluminocarbosilane (PACS) with different Al contents were prepared from different ratios of low-molecular polycarbosilane (L-PCS) and aluminum acetylacetonate [Al(AcAc)3].The mass distribution and the structure of PACS were investigated.In addition

the oxidation curing behavior of the PACS fibers was studied

in contrast to that of the PCS fibers.The results show that [Al(AcAc)3] was introduced to L-PCS by the formation of the Al(AcAc)2 hanging and the Al(AcAc) bridging.The PACS has a bimodal mass distribution

which leads to good spinnability.Both the number and reactivity of SiH in PACS decreased with the increase of the Al content.Moreover

the SiOH was prevented from forming the SiOSi crosslinking bonds

which were produced by the oxidation of SiH.As the increase of Al content

the gel-point temperature was retarded to high temperatures and the gel content increased slowly with the elevation of temperature.Consequently

excessive oxygen was introduced into the cured fibers.By means of preoxidation and self-crosslinking

the oxygen content of cured PACS fibers was reduced under 11 wt%.The self-crosslinking mechanism includes the following two ways.Firstly

the activated SiOH reacts with each other to form SiOSi by releasing H2O.Secondly

SiH reacts with SiOH or SiCH3 to form SiOSi or SiCH2Si by releasing H2.