Synthesis of lamellar isobutyl silicates and dispersion in polypropylene melts

• Published in: Journal of applied polymer science 2007-08, Vol.105 (3), p.1456-1465
• Main Authors: Chastek, Thuy T., Que, Emily L., Jarzombeck, Phil, Macosko, Christopher W., Stein, Andreas
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; hybrid materials; lamellar mesostructures; Polymer industry, paints, wood; silicates; synthetic clays; Technology of polymers
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.26315

A new synthetic clay, iC4‐LMS, which is a lamellar mesostructured silicate with isobutyl groups covalently attached to silicate sheets, was synthesized with the goal to increase the compatibility of the inorganic sheets with polypropylene (PP) in a melt‐blending process. The lamellar morphology of iC4‐LMS was confirmed using X‐ray diffraction and transmission electron microscopy. Based on 29Si and 13C{1H} CP‐MAS NMR spectra, isobutyl functional groups were attached to at least 10 mol % of silicate tetrahedral sites in the inorganic layers. These surface groups mimic the subunits in the PP chains. Samples of iC4‐LMS were mixed with several organic solvents and sonicated. The solvent most like PP, tetramethylpentadecane, had the highest viscosity, forming a gel which indicates very good dispersion of the clay. However, when iC4‐LMS was melt‐blended with PP, it did not show significant increase in rheology. This modest effect on rheology may arise from fracture of iC4‐LMS layers as a result of the shear stresses during melt blending produced by the viscous PP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007