Polymethylmethacrylate-montmorillonite composites: preparation, characterization and properties

The objective of this work was directed to solve a problem of polymerizatio n shrinkage in acrylic resin polymethylmethacrylate (PMMA) material. Organo philic montmorillonite (claytone) was added up to 1% by weight to one comme rcial type of PMMA powder to form PMMA-MMT composite. Acrylic specimens wer e processed by the conventional heat curing method following manufacturer's instructions. Thermogravimetric analysis data indicates that polymer-clay composites exhibit significant increase in thermal stability with very smal l amount of inorganic content. The morphology of the composites was verifie d using scanning electron microscopy revealing the absence of large mineral aggregates. Interlamellar spacing was measured from wide angle X-ray diffr action. The d(001) spacing of clay was expanded to 18 Angstrom in claytone and the intensity of the peaks is progressively reduced with increasing the concentration of polymer in the composites samples. Warpage and linear dim ensional change measurements were achieved using 'traveling microscope' and one way analysis of Variance was employed to compare results. The results indicated that there was a significant decrease of warpage and linear dimen sional changes between PMMA specimens and that of PMMA-MMT composite materi als. (C) 2001 Elsevier Science Ltd. All rights reserved.