Precision Engineering 30 (2006) 71–84 A tensile test device for in situ atomic force microscope mechanical testing Eberhard Bamberg a,b,∗ , Christian P. Grippo b , Panitarn Wanakamol c , Alexander H. Slocum b , Mary C. Boyce b , Edwin L. Thomas c a Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA b Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA c Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Received 8 December 2003; received in revised form 20 April 2005; accepted 10 May 2005 Available online 6 July 2005 Abstract The microstructure and mechanical behavior of polymeric-based materials can be controlled at the micro- and nanometer length scales through blending, copolymerization, and the incorporation of micro- and nanometer particles. To facilitate the study of morphology, deforma- tion mechanisms, and mechanical properties of micro- and nanocomposite materials, a tensile testing machine with an integral commercial atomic force microscope (AFM) was designed and built. This testing machine determines the macroscopic stress–strain behavior of materials under different controlled loading conditions, and simultaneously allows the microscopic structure changes to be observed using the AFM. © 2005 Elsevier Inc. All rights reserved. Keywords: Atomic force microscope; Nanocomposites; Microcomposites; Stress–strain behavior; Chevron effect; Triblock copolymer; Mechanical testing; Tensile testing 1. Introduction This paper focuses on the design, manufacture, and test- ing of an in situ testing machine that in combination with a commercial atomic force microscope (AFM) measures the macroscopic stress–strain behavior of polymeric-based micro- and nanocomposite materials under controlled load- ing conditions; it also allows the straining microscopic struc- ture to be observed with nanometer resolution. Nanocomposites are polymeric-based materials that have significantly enhanced mechanical performance as well as other properties such as electrical conductivity, resistance to permeability and abrasion resistance while maintaining the low inherent density of polymers. The microstructure and mechanical behavior of polymeric materials can be tailored via the incorporation of second phase particles into the poly- mer, which can be done, for example, through the blending ∗ Corresponding author. Tel.: +1 801 585 0722; fax: +1 801 585 9826. E-mail address: bamberg@mech.utah.edu (E. Bamberg). of two or more polymers, and through copolymerization. These processes act to produce multi phase morphologies where the length scales of the different underlying phases may range anywhere from nanometers to tens or hundreds of micrometers. The microscopic geometry and properties of the constituent phases governs the resulting macroscopic mechanical behavior [1–5]. In order to better design and tailor polymeric-based blends, micro- and nanocomposites, a better understand- ing is needed of the connections between microstructure and mechanical behavior. Typically, specimens are evalu- ated before and after tensile testing using instruments such as atomic force microscopes [6–12]. Bobji and Bhushan [7] successfully performed in situ tensile testing on magnetic tapes in order to study the growth of microcracks. The exper- iments observed the growth of these cracks with an AFM as a function of strain, but did not include any measurements of the occurring stresses. Oderkerk et al. [6] used a man- ual stretching device capable of producing a maximum strain of 100% to test 20 m thin nylon-6 samples. The stretching 0141-6359/$ – see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.precisioneng.2005.05.001