摘要
研究了ＬＰＳＺ／ＤＶＢ的交联反应及其对裂解产物的影响实验表明；其交联反应以加成和缩合反应的两种方式同时进行加成反应的温度为１５０℃左右，部分加成反应的结果使其交联裂解产物的孔洞尺寸减小，裂解产物的裂解产率提高裂解产物主要由非晶态Ｓｉ３Ｎ４和β－ＳｉＣ组成，还有少量ＳｉＯ２和游离Ｃ，加入ＤＶＢ后。
The crosslinking and pyorlysis of LPSZ/ DVB system have been investigated by means ofTG-DTA,IR, XRD, SEM and element analysis. The experiment results show that the crosslinking occursaround 150℃ in the case of catalyst. The reaction mechanisms are in both addition between -CH = CH2 andSt--H and condensation between-CH = CHZ and Si-H or Si-H and N-H. The partial addition reaction results in reduced porosity of the pyrolysis products and is related to high char yields on pyrolysis. It has beenfound that crosslinking under nitrogen pressure (0.5 MPa) is essential for preventing evaporation of LPSZand subsequent stoichiometry change of the pyrolysisproducts. The element analysis show that the N contentof the pyrolysed LPsz / DvB crosslinking in nowing nitrogen is only about 1.48 wt-%. The pyrolysis products are mainly composed of a mixture of amorphous St,N.and small crystallites of β-SiC in addition to minor SiO2 and free carbon. This high freecarbon content has to be related to the crosslinking reaction involving the vinyl groups. However, the shrinkage during pyrolysis is still large, which is evident from thecracks of the samples. The LPSZ/ DVB system seems promising for 3D CMCs processing. It has lowviscosity, can be crosslinked at lower temperature and possesses high char yield upon pyrolysis. Butoptimisation is still needed to reduce bloating and shrinkage.
出处
《材料研究学报》
EI
CAS
CSCD
1994年第2期163-168,共6页
Chinese Journal of Materials Research
关键词
聚硅氮烷
二乙烯基苯
陶瓷复合材料
low molecular weight polysilazane
divinylbenzene
crosslinking
pyrolysis products
preceramic polymer
