MINERALS & METALLURGICAL PROCESSING Vol. 27 No. 1 • February 2010 1 Utilizing minerals and materials with negative properties G.W. Douglas, S. Schnabel, L. Kjerengtroen, W.M. Cross and J.J. Kellar South Dakota School of Mines and Technology, Rapid City, South Dakota Abstract The need for dimensionally stable filled polymer composites has spurred the quest for materials that possess a negative coefficient of thermal expansion (CTE). Finding minerals and materials with a negative CTE large enough to counteract the substantial CTE found in polymers proves challenging. Much research has been per- formed over the last decade to uncover various materials that possess this unusual behavior. A list of materials that have demonstrated negative properties are discussed, as well as the experimental use of one such material (ZrW 2 O 8 ), in a polymer matrix composite. Other negative properties, such as negative Poisson’s ratio and nega- tive stiffness, are also examined. Key words: Negative properties, Coefficient of thermal expansion, Zirconium tungstate Introduction Paper number MMP-09-008. Original manuscript submitted February 2009. Revised manuscript accepted for publication September 2009. Discussion of this peer-reviewed and approved paper is invited and must be submitted to SME Publica- tions Dept. prior to August 31, 2010. Copyright 2010, Society for Mining, Metallurgy, and Exploration, Inc. INVITED FEATURE