Reactive Compatibilization of Impact Copolymer Polypropylene and Organically Modified Mesoporous Silica to Prepare Composites Possessing Enhanced Mechanical Properties

Abstract

Mesoporous silica was evaluated as functionalized filler in impact copolymer polypropylene (ICP) in its original form as well as after organic modification. Mesoporous silica was synthesized by base-catalyzed hydrolysis of tetraethyl orthosilicate in the water–acetone medium. The organic modification of mesoporous silica was carried out using commercially available silane with a terminal unsaturated bond and by synthesizing silane precursor by chemical treatment via TEMPO-initiated thiol–ene chemistry to introduce alkyl chains terminating in hydroxyl groups. The characterization for all types of mesoporous silica prepared was done using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), solid-state nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). ICP–mesoporous silica composites were prepared using 1, 5, and 10 phr mesoporous silica and organically modified mesoporous silica loading via reactive compatibilization and were tested for their thermal, morphological, rheological, and mechanical properties. The addition of mesoporous and organically modified mesoporous silica enhanced thermal stability and nucleation with respect to neat ICP. Tensile and flexural moduli were improved while maintaining their impact strength. Analysis of rheological properties revealed a rise in zero-shear rate viscosity in ICP–mesoporous silica composites. DMA studies showed higher storage and loss modulus with the addition of mesoporous silica in ICP.