Research Signpost 37/661 (2), Fort P.O. Trivandrum-695 023 Kerala, India EM Shielding – Theory and Development of New Materials, 2012: ISBN: 978-81-308-0499-6 Editors: Maciej Jaroszewski and Jan Ziaja 4. Polymer based nanocomposites for electromagnetic interference (EMI) shielding Veena Choudhary 1 , S.K. Dhawan 2 and Parveen Saini 2 1 Centre for Polymer Science & Engineering, Indian Institute of Technology New Delhi-110 016, India; 2 Polymeric & Soft Materials Section CSIR-National Physical Laboratory, New Delhi-110 012, India Abstract. The rapid growth of electronics and instrumentation has led to electromagnetic interference (EMI) as an off-shoot. The mutual interference among business machines, process equipments and other electronic gadgets often lead to disturbance or complete breakdown of normal performance of appliances. Polymer nanocomposites represent a novel class of materials that possess unique combination of electrical, thermal, dielectric, magnetic and/or mechanical properties which are useful for suppression of electromagnetic noises. This chapter will throw some light on the basics of EMI shielding/microwave absorption, various techniques for measurement of shielding effectiveness, theoretical aspects of shielding, governing equations, different strategies and potential materials for handling of EMI with special reference to polymer nanocomposites based on conducting polymers, carbon nanotubes (CNTs), graphene, dielectric (BaTiO 3 , TiO 2 etc.) or magnetic (γ- Fe 2 O 3 , Fe 3 O 4 , BaFe 12 O 19 etc.) as filled inclusions. Correspondence/Reprint request: Dr. Veena Choudhary, Centre for Polymer Science & Engineering, Indian Institute of Technology, New Delhi-110 016, India