Poly(vinyl acetate)/silica-filled materials: material properties of in situ vs fumed silica particles

Abstract

Composites of poly (vinyl acetate) (P V Ac) and silica were prepared from the in situ polymerization of acid-catalyzed tetraethoxysilane. The physical properties of these composites were compared with those of PVAc/fumed silica (of 7-nm nominal particle size) composites prepared by both melt-milling and solutioncasting from tetrahydrofuran or carbon tetrachloride. Their morphologies were examined by transmission electron microscopy and small-angle X-ray scattering revealing that, although all the materials were optically transparent, differences in the primary particle size and interfacial regions exist. Infrared spectroscopy showed that substantially more hydrogen bonding occurs in the in situ prepared composites. The dielectric, dynamic mechanical, and ultimate mechanical properties of the composites indicated that a connected, supporting silicate network phase is formed at much lower concentrations of silica in the in situ prepared composites. This is shown to have a substantial effect on the tensile properties of the composite at temperatures above the glass transition temperature (Tg) of PVAc but does not dramatically influence these properties below Tf.

Recent Applications of Ionic Liquids in the Sol-Gel Process for Polymer–Silica Nanocomposites with Ionic Interfaces

“…The Wilkes morphological model described the O-I polymer as a hybrid network consisting of flexible polymer-rich domains with dispersed glassy silica-rich domains and a mixed interface. Since then, many in situ formed polymer-silica nanocomposites based on polypropylene (PP) [113][114][115], polyvinyl acetate (PVA) [116], polyvinyl alcohol (PVOH) [117][118][119], high amorphous vinyl alcohol (HAVOH) [11], polymethyl methacrylate (PMMA) [120], polydimethylsiloxane (PDMS) [121,122], polyacrilate [123,124] and epoxy matrix [4,7,112], were successfully synthesized.…”

Nanostructure and properties of polysiloxane-layered silicate nanocomposites

“…For example, poly(vinyl acetate) nanocomposites reinforced with in situ sol-gel derived silica demonstrate remarkably higher tensile properties above the glass-transition temperature (T g ) when compared to samples reinforced with conventional fumed silica. 4 The enhancements were attributed to extensive hydrogen bonding between the polymer and the in situ derived silica samples, which was not observed in samples reinforced with fumed silica. Mark and coworkers have also noted significant enhancements in ultimate strength and rupture energy in poly(dimethyl siloxane) (PDMS) reinforced with nanosize, in situ sol-gel derived silica when compared to PDMS composites filled with fumed silica.…”

Thermal stability and degradation kinetics of poly(methyl methacrylate)/layered copper hydroxy methacrylate composites

“…For example polymer nanocomposites containing metal, silica or metal oxide nanoparticles have been shown to exhibit enhanced mechanical, magnetic, optical, or electrical properties. 8,12,15,[22][23][24] In the work reported here, a LHS additive, copper hydroxy methacrylate (CHM) is added to PMMA via solution blending and bulk polymerization. Composites are analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy.…”