摘要
以八甲基环四硅氧烷为单体,四甲基氢氧化铵为催化剂,水作封端剂,在较高温度、排氧加压密闭的条件下,一步合成羟基聚硅氧烷。采用重量法测定转化率,根据聚合机理,导得动力学模型:ee[]ln{1}1[]1[]bkBtAA-=---。在此基础上,探讨温度、催化剂、水量等条件对聚合速率及聚合物特性粘数的影响,得到聚合活化能为91.4kJ穖ol-1。研究还发现,反应混合物粘度和聚合物特性粘数随转化率单调递增,这为连续法一步合成羟基硅氧烷创造了条件。
Hydroxy terminated polydimethylsiloxane (PDMS) was directly synthesized, with tetramethyl ammonium hydroxide (TMAH) as catalyst and octamethylcyclotetrasiloxane (D4) as monomer, under the conditions of high temperature, adding water and oxygen-off. It is named one-step process, and the kinetics research of this process was performed by means of weight method. The kinetic model was derived based on the analysis of reaction mechanism: ln{1-[B]/1-[A]c}=-{kb/1-[A]c}t. The activation energy was calculated out to be 91.4 kJ·mol-1, and the effects of reaction conditions on polymerization rate and [η] of product were studied too. The results show that the polymerization rate increases and the value of [η] decreases with temperature increasing; the polymerization rate and the value of [η] decrease together with water concentration increasing; the polymerization rate increases and the value of [η] increases firstly, and then decreases with catalyst concentration increasing. It is found that the viscosities of reaction mixtures and the values of [η] of products increase gradually with conversion, which makes this one-step process can be used as a continuous producing process in industrial production.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2004年第3期314-318,共5页
Journal of Chemical Engineering of Chinese Universities
基金
教育部高等学校重点实验室访问学者基金
关键词
水
羟基聚硅氧烷
一步合成法
动力学特征
Catalysis
Kinetic theory
Polymerization
Reaction kinetics
Water
