核壳型丁苯胶乳对水泥基复合材料力学性能的影响及其作用机制

Effect of styrene-butadiene latex with core-shell structure on the mechanical properties of cement-based composite materials and its mechanism

针对地层、水泥环、套管三者之间形变不协调而导致的三者层间封隔失效等问题,采用种子乳液聚合的方法,将功能单体2-丙烯酰胺基-2-甲基丙磺酸与苯乙烯接枝到低分子量液体聚丁二烯上,合成了一种稳定性良好的丁苯胶乳增韧剂TEL-100L胶乳。TEL-100L胶乳的结构及性能评价表明:TEL-100L胶乳具有良好的热稳定性和明显的核壳结构。水泥石的力学性能评价表明:TEL-100L胶乳可明显降低水泥石的脆度系数和弹性模量,提高水泥石的韧性及力学形变能力。对TEL-100L胶乳增韧机制的研究表明:TEL-100L胶乳不仅可以通过静电吸引作用吸附到水泥颗粒表面,而且可以通过Ca2+的桥接作用与水泥水化体系交错连接,形成致密的三维网状结构,从而提高水泥基复合材料的韧性和力学形变能力。

The deformation of cement sheath is often inconsistent with that of casing and formation,which leads to the failures of zonal isolation.In order to solve the problems,a kind of styrene butadiene rubber latex possessing good stability was synthesized by grafting 2-acrylamido-2-methyl-propane sulfonic acid and styrene to the liquid polybutadiene with low molecular weight via seed-emulsion polymerization.The structure and properties characteristics indicate that TEL-100 Llatex possesses good thermal stability and perfect core-shell structure.For oil well cement stone,the evaluations of mechanical property show that TEL-100 Llatex can significantly reduce the brittleness coefficient and elasticity modulus of cement stone,and improve its toughness and deformation ability.The exploration of toughening mechanism finds that TEL-100 Llatex can not only be adsorbed onto the cement grains surface by electrostatic attraction,but also can be cross connected with cement hydration system through the complexation with Ca2+,which leads to the formation of compact three-dimensional net structure and the improvement of toughness and deformation ability.