Micromechanical deformation processes in PA/layered silicate nanocomposites: Correlation of structure and properties
Micromechanical deformation processes in PA/layered silicate nanocomposites: Correlation of structure and properties
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DOI：
10.1002/pen.20767
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发表时间：
2007-08
影响因子：
3.2
通讯作者：
Károly Renner;S. Henning;J. Móczó;M. Yang;H. Choi;B. Pukánszky
中科院分区：
文献类型：
--
作者：
Károly Renner;S. Henning;J. Móczó;M. Yang;H. Choi;B. Pukánszky
以两种有机干度不同的硅酸盐为原料，制备了聚酰胺/亲有机蒙脱土纳米复合材料；以未包覆蒙脱土钠为对照。复合材料的硅酸盐含量在0 ~ 10 vol%之间经过7个步骤变化。通过x射线衍射和电子显微镜对复合材料的结构进行了表征。微力学变形过程之后是声发射和体积应变测量。复合材料的结构比通常声称的要复杂；它们含有单独的硅酸盐薄片、不同嵌入程度的附着体和较大的颗粒。试件伸长过程中以弹性变形和剪切屈服为主。基体聚合物和复合材料的变形机理不同。前者以空化的方式发出声音，而复合材料中的声发射过程则是相关的片状和非剥离颗粒。声波事件主要是由粒子断裂产生的。基质/硅酸盐黏附似乎很强，很少发生脱粘，体积增加主要是由颗粒破坏引起的。用于有机干燥的表面活性剂的类型和数量在确定变形过程和性能方面起着重要作用，因为它既影响基质/填料的相互作用，也影响颗粒的固有强度。
Polyamide/organophilic montmorillonite nanocomposites were prepared from two silicates with different organophilization resulting in strong and weak matrix/silicate adhesion, respectively; uncoated sodium montmorillonite was used as reference. The silicate content of the composites changed between 0 and 10 vol% in seven steps. Composite structure was characterized by X-ray diffraction and electron microscopy. Micromechanical deformation processes were followed by acoustic emission and volume strain measurements. The structure of the composites is more complicated than usually claimed; they contain individual silicate platelets, tactoids with different degree of intercalation, and larger particles. Elastic deformation and shear yielding dominates during the elongation of the specimens. The matrix polymer and the composites deform according to different mechanisms. Sound is emitted by cavitation in the former, while sound emitting processes are related tactoids and nonexfoliated particles in the composites. Acoustic events are generated mainly by the fracture of the particles. Matrix/silicate adhesion seems to be strong, debonding rarely takes place, and volume increase is initiated primarily by particle failure. The type and amount of the surfactant used for organophilization plays an important role in the determination of deformation processes and properties, since it influences both matrix/filler interaction and the inherent strength of the particles.