聚硅氧烷的交联与裂解陶瓷化研究

CURING OF POLYSILOXANE AND ITS PYROLYTIC CONVERSION TO CERAMICS

研究了含氢聚硅氧烷(HPSO)与二乙烯基苯(DVB)的交联与裂解行为。结果表明,氯铂酸能有效催化两者之间的交联反应。DVB/HPSO质量比例对交联程度和陶瓷产率有明显影响。催化剂的含量为11.31×10-6、m(DVB)/m(HPSO)=0.5∶1的体系在120℃交联6h后达到完全交联状态。1000℃时裂解完全,陶瓷产率76%,产物组成为38.33%Si、27.33%O、34.34%C。DVB/HPSO的裂解陶瓷化主要发生在370℃～800℃范围内,分为两个阶段。第一阶段在420℃～610℃区间,裂解活化能为208.38kJ/mol,由随机成核步骤控制裂解反应。第二阶段在620℃～800℃区间内,裂解活化能为339.89kJ/mol,由一维扩散步骤控制裂解反应。

The curing and pyrolysis behavior of the system of hydrogen-containing polysiloxane (HPSO) and divinylbenzene (DVB) were investigated in this paper. It is found that H_2PtCl_6 is an effective catalyst for the curing of DVB/HPSO. The mass ratio of DVB/HPSO has significant influence on cure degree and ceramic yield. When DVB/HPSO solution, the mass ratio of which is (0.5)∶1, is cured at 120 ℃ for 6 h with a catalyst content of (1.131)×^(-5), its gel content is (99.3%), and its ceramic yield is (76.0%) at temperature up to 1000 ℃. The products of DVB/HPSO pyrolyzed at 1000 ℃ consist of Si, O, C whose contents are (38.33%), (27.33%), and (34.34%), respectively. The pyrolysis of DVB/HPSO includes two stages, the first is during 420 ℃～610 ℃, and the second is during 620 ℃～800 ℃. The apparent activation energies of the first and the second stage are (208.38) kJ/mol and (339.89) kJ/mol, respectively. The pyrolysis mechanism functions of the two stages are Avrami-Erofeev equation and parabola principle, respectively. The rates of pyrolysis reactions of the two stages are controlled by random nucleation and growth and one-dimensional diffusion, respectively.