Synthesis of lamellar isobutyl silicates and dispersion in polypropylene melts

A new synthetic clay, iC4-LMS, which is a lamellar mesostructured silicate with isobutyl groups cova- lently 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 29 Si and 13 C{ 1 H} CP-MAS NMR spectra, isobutyl functional groups were attached to at least 10 mol % of sili- cate 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, tetramethylpentade- cane, had the highest viscosity, forming a gel which indi- cates 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 105: 1456- 1465, 2007