Polymer/silica nanocomposites prepared via extrusion

Abstract

Three polymer/silica nanocomposites were prepared by a single‐screw extrusion approach: poly(methyl methacrylate), polystyrene and polycarbonate/silica nanocomposites. The resulting nanocomposites were subjected to comprehensive studies of mechanical, thermal and flammability properties. All materials showed improved mechanical performance and thermal stabilities, although they are not strictly flame retardant when subjected to fire tests like Oxygen Index or horizontal Bunsen burner tests. However, the nanocomposites showed reduction in peak heat release rates and total heat release when evaluated by cone calorimetry. Moreover, the polycarbonate showed improvement in flammability according to vertical burning tests. All polycarbonate materials subjected to vertical burning testing are V2 rated, but after flame times with 1% silica were significantly reduced. A flame retardant mechanism is proposed in order to understand the relationship between interfacial interaction and flammability of polymer/silica nanocomposites. Copyright © 2006 John Wiley & Sons, Ltd.

Clays, Nanoclays, and Montmorillonite Minerals

“…[56] However, flame retardancy and thermal modification are only some effects investigated using nanoclays; organophilic montmorillonite has also been studied for improving the mechanical and barrier properties of polymers. [36][37][38][39][40][41][42][43]57,58] The level of intercalation and exfoliation of nanoclays are some important characteristics in influencing the performance of nanocomposites; however, these require more research to establish the obtainable improvement in polymers. Ethylene-vinyl acetate copolymer and methylmethacrylate/poly (methyl methacrylate) mixtures for montmorillonite and organically modified montmorillonite were studied, respectively, [59,60] for this purpose.…”

“…The research has concentrated on the development of nanoclays through modifications in physical and chemical structures and on the study of the effects of nanoclays on the thermal-mechanical properties of polymers. [36][37][38][39][40][41][42][43] Montmorilionte derived from bentonite may contain sodium or calcium. Sodium montmorillonite is the main fraction in bentonite in combination with 10 to 20 pct of various minerals, including feldspar, calcite, silica, and gypsum.…”

A new method to prepare composite powders customized for high temperature laser sintering

“…Yuan et al physically added 5 wt% of graphite platelets into PEEK150PF powder and achieved a 40% increase in tensile strength, however for concentrations above 5%, in this case 7.5 wt%, the Micro-CT analysis revealed porosity in the microstructure [9], which was related to the poor powders flow and uneven heating absorption between the graphite platelets and PEEK powder during the HT-LS. One of the conventional ways to incorporate fillers into a polymer matrix is direct melt-compounding [10,11], however the high cohesive forces between nanofillers cause their severe agglomeration and poor dispersion inside the polymer matrix [12], which significantly limits the full potential of the nanofillers. Furthermore, modifying the melt compounded polymer into powder form with appropriate particle size and morphology requires following up milling or other size reduction processes that are very energy consuming and costly, needless to say the huge challenges for obtaining powders of round shape and proper size distribution by milling, especially for high performance polymers, such as PEEK [13].…”

Effect of the bentonite filler on structure and properties of composites based on hydroxyethyl cellulose

“…Effective way to solve this problem is to modify the polymer matrix by fillers insertion. Such composites may have applications in such various areas of industry as sensors, sorbents, catalysts, and membranes, as well as in biochemistry and medicine as drug templates, due to their improved mechanical, electrical, thermodynamic, antimicrobial properties (Badamshina and Gafurova, 2008;Alekseeva et al, 2009Alekseeva et al, , 2012Alekseeva et al, , 2013Weng et al, 1999;Yang and Nelson, 2006;Hwu et al, 2002). Note polymers modified using the filling agents considerably change their original parameters and acquire improved physicochemical properties even at small filler concentrations (Badamshina and Gafurova, 2008).…”