Preparation and Properties of Natural Sand Particles Reinforced Epoxy Composites Gang Sui, Soumen Jana, Amin Salehi-khojin, Sanjay Neema, Wei-Hong Zhong, * Hui Chen, Qun Huo Introduction Epoxy resins are used widely due to their good mechanical, thermal, and electrical properties. [1–4] Many types of epoxy resins have been developed, including bisphenol-A, bisphenol-F, aliphatic cyclic, novolac types, etc. To further strengthen the properties of epoxy resins, the use of an additional phase has been a common practice. Epoxy resins modified with inorganic particles such as carbon, TiO 2 , SiO 2 , Al 2 O 3 , clay and so on have shown improved performances. [5–10] For inorganic/organic composites, the size of particles and the interfacial adhesion have great effect on the properties of the resin matrix. The well- dispersed inorganic fillers in polymer matrices and com- patibility between inorganic and organic phases are important to achieve an overall good performance. [11–14] The application of nanometer materials to the thermo- setting resin for property modification is a promising channel. Compared to conventional inorganic/polymer composites that need over 30 wt.-% loading of microscale fillers, the same level of enhancements may be achieved with less than 10 wt.-% loading of well-dispersed nano- scale inorganic fillers. [15–17] However, this research is still Full Paper An epoxy composite using Cancun natural hydrophobic sand particle as filler material was fabricated in this study. Three point bending tests demonstrated an enhancement of 7.5 and 8.7% in flexural strength and flexural modulus, respectively, of epoxy composite containing 1 wt.-% sand particles without any chemical treatment involved, compared to the pristine epoxy. Scanning electron microscopy (SEM) studies revealed that the fracture toughness of the epoxy matrix was enhanced owing to the presence of sand particles in an epoxy/sand composite. Through dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA) methods, it was found that the storage modulus (E 0 ), glass transition temperature (T g ) and dimensional stability of the sand particles/ epoxy composites were increased compared to the pristine epoxy. The friction behavior of epoxy/sand system reflected that the microstruc- ture of epoxy composites was steady. These experimental results suggest that Cancun sand, as a freshly found natural micron porous mate- rial, may find promising applications in compo- site materials. G. Sui, S. Jana, A. Salehi-khojin, S. Neema, W.-H. Zhong Department of Mechanical Engineering and Applied Mechanics, North Dakota State University, Fargo, ND 58105, USA Fax: (þ1) 701 231 7139; E-mail: katie.zhong@ndsu.edu H. Chen, Q. Huo Center of Nanoscience and Nanotechnology, University of Central Florida, Orlando, FL 32826, USA G. Sui College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China Macromol. Mater. Eng. 2007, 292, 467–473 ß 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/mame.200600479 467