聚铝碳硅烷不熔化纤维中氧含量的调节

doi:10.7503/cjcu20150014

摘要/Abstract

摘要：

氧含量是SiAlCO纤维在1700 ℃以上烧结致密化, 并得到近化学计量比元素组成的关键因素, 而氧元素主要来源于前驱体聚铝碳硅烷(PACS)纤维的不熔化过程. 本文采用一种新的不熔化方法, 以预氧化-热交联的方式对PACS纤维进行不熔化处理, 实现了热解后所得SiAlCO纤维中氧含量在10%~13%(质量分数)范围内可调节. 为保证PACS纤维在热交联过程中不熔融, 其最低预氧化条件为190 ℃下保温4 h, 对应氧引入量为7.87%, 预氧化纤维在惰性气氛下450 ℃保温2 h, 可实现不熔化. 通过凝胶液相色谱(GPC)、红外光谱(IR)及热重-质谱联用(TG-MS)等方法研究预氧化和热交联过程, 结果表明, 预氧化过程主要是Si—H氧化生成Si—OH, 部分Si—OH相互缩聚, 在分子间形成Si—O—Si, 使PACS数均分子量提高. 热交联分为2个阶段, 300 ℃以下主要是残留的Si—OH之间形成Si—O—Si交联结构; 300~450 ℃主要发生Si—H与Si—CH₃之间脱H₂的缩聚反应, 形成Si—CH₂—Si交联结构.

关键词: 聚铝碳硅烷纤维, 热交联, 氧含量, SiC纤维

Abstract:

The oxygen content of the SiAlCO fibers was a key for the transformation from SiAlCO fibers to dense stoichiometric SiC fibers after sintering at >1700 ℃, which was mainly introduced during curing process. The novel preoxidation-thermal curing method was applied to the conversion of polyaluminocarbosilane(PACS) fibers and the oxygen content of the SiAlCO fibers as-pyrolyzed was adjustable in 10%—13%(mass fraction). A minimal degree of preoxidation of the PACS green fibers, which performed at 190 ℃ for 4 h leading to 7.87%(mass fraction) oxygen pick-up, is necessary for their further thermal-curing. Then, the preoxidation fibers formed crosslinking structure after thermal-curing at 450 ℃ under N₂ flow. The curing process was investigated by gel permeation chromatography(GPC), infrared spectrum(IR) and thermogravi-metric analysis-mass spectra(TG-MS). The results show that the Si—OH bonds are formed after the Si—H bonds in the structure of PACS fibers reacting with oxygen molecular during preoxidation. Additionally, partial Si—OH bonds could react with each other continuously to form Si—O—Si structure, resulting in molecular increase. During the thermal-curing process, the residue of Si—OH further react with each other at lower than 300 ℃. The formation of Si—CH₂—Si structure resulted from the reaction between Si—H bond and Si—CH₃ bond happened in the range of 300—450 ℃.

Key words: Polyaluminocarbosilane fiber, Thermal curing, Oxygen content, SiC fiber

中图分类号:

O631

TrendMD:

袁钦, 宋永才, 王国栋. 聚铝碳硅烷不熔化纤维中氧含量的调节. 高等学校化学学报, 2015, 36(6): 1213.

YUAN Qin, SONG Yongcai, WANG Guodong. Adjusting the Oxygen Content of the Cured Polyaluminocarbosilane Fibers^†. Chem. J. Chinese Universities, 2015, 36(6): 1213.

图/表 12

Table 1 Properties of L-PCS, PACS and PCS

Sample	Soften temperature/℃	$M ˉ n$	I_SiH/ $I SiC H 3$	Mass fraction(%)
Sample	Soften temperature/℃	$M ˉ n$	I_SiH/ $I SiC H 3$	Si	C	O	Al
L-PCS	145—156	1275	0.97	45.28	38.62	0.43
PACS	201—215	2923	0.68	43.60	37.68	3.23	0.67
PCS^[22]	215—225	1979	0.92	47.00	39.85	0.60

Table 1 Properties of L-PCS, PACS and PCS

Sample	Soften temperature/℃	$M ˉ n$	I_SiH/ $I SiC H 3$	Mass fraction(%)
Sample	Soften temperature/℃	$M ˉ n$	I_SiH/ $I SiC H 3$	Si	C	O	Al
L-PCS	145—156	1275	0.97	45.28	38.62	0.43
PACS	201—215	2923	0.68	43.60	37.68	3.23	0.67
PCS^[22]	215—225	1979	0.92	47.00	39.85	0.60

Fig.1 Change in ISiH/ISiCH3(a, b), gel content(a', b')(A) and oxygen content(B) of PCS(a, a') and PACS(b, b') fibers during oxidation curing process

Fig.2 Change in ISiH/ISiCH3 and oxygen content of preoxidation PACS fibers vs. curing time

Fig.3 Relationship between Mˉn and oxygen content of preoxidation PACS fibers

Fig.4 GPC curves of preoxidation PACS fibers in different conditions

Fig.5 Change in gel content of preoxidation PACS fibers vs. thermal-curing temperature

Fig.6 IR spectra of PACS fibers in different state PACS: green fibers; A-190-4: preoxidation fibers;T-190-4: thermal cured fibers.

Fig.7 Change in Ix/ICH and gel content of A-190-4 vs. thermal-curing temperature

Fig.8 TG(A) and MS(B) curves of A-190-4 heated at 10 ℃/min from room temperature to 500 ℃ in N2

Fig.9 TG curves of PACS fibersPACS: green fibers; A-190-4: preoxidation fibers; T-190-4: thermal cured fibers.

Table 2 Oxygen content after pyrolysis of different cured PACS fibers

Sample	T-190-4	T-190-5	T-200-3	T-200-4	T-200-5	T-240-2
Oxygen content after pyrolysis(%)	10.37	11.26	10.80	11.22	12.73	15.2

Fig.10 SEM images of SiAlCO fibers derived from T-190-4 surface(A) and cross-section(B)

参考文献 25

[1]	Bunsell A. R., Piant A., J. Mater. Sci., 2006, 41(3), 823—839
[2]	Zhao D. F., Wang H. Z., Li X. D., J. Inorg. Mater., 2009, 24(6), 1097—1104
	(赵大方, 王海哲, 李效东.无机材料学报, 2009,24(6), 1097—1104)
[3]	Yutai K., Kazumi O., Chunghao S., Katoh Y., Ozawa K., Shih C., Nozawa T., Shinavski R. J., Hasegawa A., Snead L. L., J. Nucl. Mater., 2014, 448(1—3), 448—476
[4]	Liu H. T., Tian H., J. Eur. Ceram. Soc., 2012, 32(10), 2505—2512
[5]	Wang D. Y., Song Y. C., Jian K., J. Inorg. Mater., 2012, 27(2), 162—168
	(王得印, 宋永才, 简科.无机材料学报, 2012,27(2), 162—168)
[6]	Ishikawa T., Adv. Polym. Sci., 2005, 178, 109—144
[7]	Wang D. Y., Mao X. H., Song Y. C., Wang Y. D., J. Inorg. Mater., 2009, 24(6), 1209—1212
	(王得印, 毛仙鹤, 宋永才, 王应德.无机材料学报, 2009,24(6), 1209—1212)
[8]	Wang J., Feng C. X., Song Y. C., Acta Chim. Sinica, 1998, 56(1), 77—88
	(王军, 冯春祥, 宋永才.化学学报, 1998,56(1), 77—88)
[9]	Zheng C.M., Zhu B., Li X. D., Wang Y. F.,Acta Polym. Sinica, 2004, (2), 246—250
	(郑春满, 朱冰, 李效东, 王亦菲. 高分子学报, 2004, (2), 246—250)
[10]	Mao X. H., Song Y. C., Li W., Yang D. X., J. Appl. Polym. Sci., 2007, 105(3), 1651—1657
[11]	Takeda M., Imai Y., Ichikawa H., Ishikawa T., Seguchi T., Okamura K., Ceram. Eng. Sci. Proc., 1991, 12(7/8), 1007—1018
[12]	Shimoo T., Katase Y., Okamura K., Takano W., J. Mater. Sci., 2004, 39(20), 6243—6251
[13]	Ishikawa T., Kohtoku Y., Kumagawa K., Yamamura T., Nagasawa T., Nature, 1998, 39, 773—775
[14]	Zheng C. M., Li X. D., Wang H., Zhao D. F., Hu T. J., Chem. J. Chinese Universities, 2007, 28(9), 1771—1775
	(郑春满, 李效东, 王浩, 赵大方, 胡天骄.高等学校化学学报, 2007,28(9), 1771—1775)
[15]	Ishikawa T., Kajii S., Matsunaga K., Hogami T., Kohtoku Y., Nagasawa T., Science, 1998, 282, 1295—1297
[16]	Chen L. F., Zhang L., Cai Z. H., Yu Y. X., Gu H., Zhang L. T., J. Am. Ceram. Soc., 2008, 91(2), 428—436
[17]	Hasegawa M., Iimura M., Yajima S., J. Mater. Sci., 1980, 15(3), 720—728
[18]	Laine R. M., Babonneau F., Chem. Mater., 1993, 5(3), 260—279
[19]	Li Y. Q., Song Y. C., Chem. J. Chinese Universities, 2014, 35(10), 2272—2280
	(李永强, 宋永才.高等学校化学学报, 2014,35(10), 2272—2280)
[20]	Cao F., Kim D. P., Li X. D., Feng C. X., Song Y. C., J. Appl. Polym. Sci., 2002, 85(13), 2787—2792
[21]	Yang J. M., Yang L. J., Yu Y. X., Cheng X., Zhang Y., Chem. J. Chinese Universities, 2009, 30(12), 2525—2529
	(杨景明, 杨露姣, 余煜玺, 程璇, 张颖.高等学校化学学报, 2009,30(12), 2525—2529)
[22]	Wang Y.F., High Temperature Properties of Continuous SiC Fibers and the Improved Process Based on Thermal Crosslinking, National University of Defense Technology, Changsha, 2004
	(王亦菲. 连续碳化硅纤维高温性能及基于热交联的改进工艺研究, 长沙: 国防科技大学, 2004)
[23]	Hasegawa Y., J. Mater. Sci., 1989, 24(4), 1177—1190
[24]	Sugimoto M., Shimoo T., Okamura K., Seguchi T., J. Am. Ceram. Soc., 1995, 78(4), 1013—1017
[25]	Lei Y. P., Wang Y. D., Song Y. C., Li Y. H., Wang H., Deng C., Xie Z. F., Chem. J. Chinese Universities, 2011, 32(5), 1188—1193
	(雷永鹏, 王应德, 宋永才, 李义和, 王浩, 邓橙, 谢征芳.高等学校化学学报, 2011,32(5), 1188—1193)