On the steady shear behavior of hydrophobic fumed silica suspensions in PPG and PEG of low molecular weight. Issue 1 (2nd January 2017)

• Record Type: Journal Article
• Authors: Rubio-Hernández, F. J.; Gómez-Merino, A. I.; Páez-Flor, N. M.; Velázquez-Navarro, J. F.
• Is Part Of: Soft materials. Volume 15:Issue 1(2017)
• Page Start: 55
• Page End: 63
• Publication Date: 2017-01-02
• Subjects: Hydrophobic fumed silica -- polypropylene glycol -- polyethylene glycol -- steady shear behavior; Materials science -- Periodicals; 620.11
• DOI: 10.1080/1539445X.2016.1242501
• Languages: English
• ISSNs: 1539-445X

Abstract

ABSTRACT: Fumed silica with n-hexadecane molecules anchored onto its surface (Aerosil ® R816) was dispersed in polypropylene glycol of low molecular weight (PPG400). This system showed a complex steady shear behavior: shear-thickening between two shear-thinning regions. Only shear-thinning behavior was observed when R816 was dispersed in polyethylene glycol of low molecular weight (PEG200). To conciliate both experimental results, Raman spectra of linear hexadecane, n-hexadecane/PPG400, and n-hexadecane/PEG200 mixtures were obtained. Results pointed out a distinct population of conformers could exist in each n-hexadecane-polymer mixture. More specifically, alkyl chains acquired straighter conformation in the PPG400 solvent, while the same alkyl chains showed globular conformations in PEG200.