International Journal of Innovative Science and Modern Engineering (IJISME) ISSN: 2319-6386, Volume-2, Issue-8, July 2014 11 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Pvt. Ltd. Abstract— this paper presents a comparative study on mechanical and magnetic properties of two sets, each including five samples of film-shaped magnetorheological nanocomposites (MRNCs) based on RTV silicone rubber and nano-sized carbonyl iron particles (CIPs). One set of sample was prepared by polymerization of silicone rubber with CIPs and silicone oil, while the other set obtained by filling the ammonium bicarbonate (NH4HCO3), CIPs and silicone oils. Both set of samples were manufactured under isotropic condition and their microstructures was characterized by XRD and EFSEM. Porosity characteristics was measured by displacement method and porosity image analysis was applied using ImageJ and Origin Pro Software. The mechanical tensile tests was conducted using Gotech tensile strength tester and the density of samples was observed experimentally and estimated theoretically. The magnetic properties of MRNCs were practically determined using VSM test. Plateau stress induced by the applied magnetics fields and MR effects was determined. Through fabrication of film-shaped MRNCs, the samples deflections was measured against applied magnetic fields .The comparative investigation results show that porosity improve the mechanical and magnetic properties of MRNCs and porous MRNCs will be the good candidate for miniature and flexible gripper’s jaws. Index Terms—Carbonyl Iron, MRNCs, Porosity, Silicone Rubber I. INTRODUCTION Magneto-Rheological Nanocomposites (MRNCs) are the new category of smart magnetorheological materials which are sensitive against applied magnetic fields. MRNCs consisting of nano-sized CIPs embedded in a silicone rubber matrix, display a variety of interesting properties to design the flexible actuators [1-4]. MRNCs have a good prospect for engineering applications. A very interesting application that will benefit from the specific characteristics of this smart composite is the miniature devices as well as grippers [5]. According to the literature and aiming the property enhancement for MR family composites as MR micro Manuscript received June 2014 Aref Naimzad, PhD Student, Manufacturing Department, Mechanical Engineering Faculty, Tarbiat Modares University, Tehran, Iran. Dr.Yousef Hojjat, Associate Professor, Manufacturing Department, Mechanical Engineering Faculty, Tarbiat Modares University, Tehran, Iran Dr.MojtabaGhodsi, Assistant Professor, Manufacturing Department, Mechanical Engineering Faculty, Tarbiat Modares University, Tehran, Iran composites, MR elastomers and MRNCs, the different ideas have applied and different research works has conducted. The authors are aware of only a few reports of MR composites containing nano-sized CIPs and Iron particles. In one instance, a brief report is discussing on MR nanocomposites with 1 wt. % of MWNTs in the silicone rubber and 20 vol. % of iron. In this work, the researcher characterized the dynamic mechanical behaviour of MRNCs through shear test, and noted that MRNCs exhibit higher zero-field stiffness and absolute MR effect [1]; While the another one points to the mechanical property improvement using micro and nano-sized CIPs and iron oxide powder without any clear data summary [2]. The Author’s previous works [3-5] were focused to fabricate a light-weight and flexible nonporous MRNCs for miniature gripper applications using laser ablated nano powder of CIPs. The magnetic property values of manufactured MRNCs were determined lower than current reported work and the different fabrication technologies have been tested as hot press, chemical vacuum vaporization and laser beam moulding. Generally, in magnetorheological composites based on silicone rubber, the increase in particle percentages considering a constant magnetic field, causes the increase in deflection and magnetic permeability values [6].The deflection of MR composite when exposing to a uniform magnetic field is dependent on the distribution of particles inside the composites and results from complex magnetic interaction between particles and mechanical interaction between particles and rubber-like matrix [7]. Besides that, The MR elastomer composites show the mechanical properties enhancement during the tensile test. Y. Wang et al [8] developed the MR elastomers based on immiscible silicon rubber via co-solvent method and noticed that MR elastomers had a higher tensile strength and lower elongation at break than that of MR elastomers based on pure silicone rubber. In some MR elastomers composite category containing CIPs, RTV silicone rubber and silicone oil, the CIPs by itself has a measurable impact on dynamic mechanical property [9]whilst in MR nanocomposites based on MWNTs and liquid state silicone rubber, the higher magnetic field-induced increase the dynamic properties [10]. Recently, the performance of porous magnetorheological elastomers were evaluated regarding Comparative Study on Mechanical and Magnetic Properties of Porous and Nonporous Film-shaped Magnetorheological Nanocomposites Based on Silicone Rubber Aref Naimzad, Yousef Hojjat, Mojtaba Ghodsi