Effect of Grafting on Rheology and Structure of a Simplified Industrial Nanocomposite Silica/SBR

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• 作者：Guilhem P. Baeza ; Anne-Caroline Genix ; Christophe Degrandcourt ; Laurent Petitjean ; J茅r茅mie Gummel ; Ralf Schweins ; Marc Couty ; Julian Oberdisse
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：August 27, 2013
• 年：2013
• 卷：46
• 期：16
• 页码：6621-6633
• 全文大小：627K
• 年卷期：v.46,no.16(August 27, 2013)
• ISSN：1520-5835

文摘

An un-cross-linked SBR-system filled with precipitated silica nanoparticles of radius 鈮?0 nm by mixing is studied as a function of the fraction of graftable matrix chains (140 kg molp>鈥?p>) varying from 0% to 100%, for a low (桅_Si = 8.5 vol %) and high (16.7 vol %) silica volume fraction. The linear rheology in shear shows a strong impact of the grafting on the terminal flow regime, and a shift to longer relaxation times with increasing grafting. Simultaneously, the plateau modulus stays approximately constant for the low 桅_Si, suggesting a link to the silica content. The microstructure of the silica is characterized by using a combination of transmission electron microscopy and small-angle X-ray scattering data. We apply a quantitative model of interacting aggregates, and determine the average aggregation number (decreasing from 160 to 30 with grafting), aggregate size (50 to 30 nm), and compacity (55% to 35%). While the linear rheology seems to be dominated by the matrix composition, both the mixing rheology and the structure display a saturation with increasing grafting fraction. A closer analysis of this effect indicates that a critical amount of grafting is needed to trigger structural evolution. To summarize, a quantitative study of complex nanocomposites with several features of industrial systems demonstrates that the grafting density can be used as a fine-tuning parameter of rheology and microstructure.