Use of Sonication and Influence of Clay Type on the Enhancement in Physical Properties of Poly(methyl methacrylate) Nano
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1056-HH10-05
Use of Sonication and Influence of Clay Type on the Enhancement in Physical Properties of Poly(methyl methacrylate) Nanocomposites Sharon Ingram1,2, Hugh Dennis2, Ian Hunter2, John J Liggat1, Craig McAdam1, Richard A Pethrick1, Carl Schaschke3, Sylwia K Staszczak1,2, and David Thomson2,3 1 Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow, G1 1XL, United Kingdom 2 Carron Phoenix Ltd, Falkirk, United Kingdom 3 Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow, G1 IXJ, United Kingdom ABSTRACT The nature of the dispersion of a clay platelet in a resin composite will play an important role in the process of enhancement of the physical properties of that material. This paper describes studies of ultrasonically and mechanically mixed dispersion of various clays in methyl methacrylate (MMA) and reports the effects of organic surface modification on the rheology, suppression of settlement of filled systems, cure characteristics and final mechanical properties.
INTRODUCTION Over the last ten years the incorporation of organically modified exfoliated montmorillonite [OMEM] clays into thermoplastics and thermosets has been an active area of research1. The changes in physical properties which are observed depend on the nature of the interactions between the polymer and the clay and the nature of the dispersion of the clay. A series of papers have been published on OMEM’s in poly(methylmethacrylate) -PMMA2-7 and demonstrates the type of enhancement in physical properties which can be achieved in these systems. Key to achieving property enhancement is the exfoliation of the clay platelets and this is conventionally achieved by organophilic modification of the surface by means of cation exchange allowing dispersion to be achieved using shear forces 1 In certain systems effective dispersion has required use of ultrasonic irradiation which is not compatible with many applications3,4. The nature of the organophilic modification can influence the coupling between the polymer and the clay resulting in either lowering or increasing properties such as Tg3-8. Garamite is an organically modified mixed clay system which is a mixture of platelets and ribbons like clay particles9-11. Ribbon like structures are found in sepiolite and palygorskite clays12 and when mixed with platelets modify the rheological properties and make dispersion of the clay more easily achieved. The fibrous ribbon structure of Garamite 1958 has been observed by Scanning Electron Microscopy13 with fibre sizes generally between ~100Å and 3µm in length, ~100 - 300µm in width and ~50 - 100Å thick14 and can aid processing, but at high concentrations has deleterious effects on mechanical properties13.
EXPERIMENT
Nano particulates and polymers used in composite fabrication. A series of organically modified smectite clays were obtained from Southern Clay Products, Texas. Cloisite 30B is a mica type silicate with bis-2-hydroxyethyl methyl tall
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