Effect of Nano-Magnetite Particle Content on Mechanical, Thermal and Magnetic Properties of Polypropylene Composites Luca Di Palma, 1 Irene Bavasso , 1 Fabrizio Sarasini, 1 Jacopo Tirill  o, 1 Debora Puglia, 2 Franco Dominici, 2 Luigi Torre, 2 Armando Galluzzi, 3 Massimiliano Polichetti, 3 Mahammadali Ahmed Ramazanov, 4 Flora V. Hajiyeva, 4 Habiba A. Shirinova 4 1 Department of Chemical Engineering Materials Environment, Sapienza-University of Roma, Roma, Italy 2 Department of Civil and Environmental Engineering & UdR INSTM, University of Perugia, Terni, Italy 3 Department of Physics “E.R. Caianiello”, University of Salerno and CNR-SPIN, Fisciano, SA, Italy 4 Faculty of Physics, Baku State University, Baku, Azerbaijan Magnetic nanoparticles embedded in polymer matrices have excellent potential for electromagnetic device applications, like electromagnetic interference sup- pression or strain sensing applications in the structural health monitoring domain. In this work, polymer nano- composites of polypropylene loaded with varying con- centrations of magnetite nanoparticles (from 2 to 40 wt%) have been synthesized by an ex situ process. The magnetite nanoparticles were produced using a simple co-precipitation technique. The nanocompo- sites were characterized by differential scanning calo- rimetry, scanning electron microscopy, tensile and hardness testing, vibrating sample magnetometry. The mechanical properties were found to be dependent on the degree of dispersion and on the strong nucleating ability of magnetite nanoparticles, while a superpara- magnetic behavior was reported. These composites have tailorable mechanical and magnetic properties highly dependent on the content of magnetic filler. POLYM. COMPOS., 39:E1742–E1750, 2018. V C 2018 Society of Plastics Engineers INTRODUCTION In the last decade, there has been tremendous develop- ment in the use of magnetic nanoparticles for manufactur- ing composite materials where the combination of units with at least one dimension <100 nm provides innovative functional materials tailored to meet the requirements of a broad spectrum of applications, ranging from technical to biomedical ones [1–4]. In this regard, different materials and different material combinations are possible, with a particular emphasis on nanosized oxide materials such as magnetite (Fe 3 O 4 ), maghemite (g-Fe 2 O 3 ), and hematite (a-Fe 2 O 3 ) [5–7] in polymers. These nanoparticles are characterized by magnetic moment in combination with a good chemical stability and low toxicity and can be man- ufactured by different methods including hydrothermal techniques, sol–gel processing, surfactant assisted synthe- sis, co-precipitation, microemulsion techniques, and solu- tion combustion [8–14]. These synthetic routes offer various degree of control over the shape, size distribution, crystallinity, and magnetization values of iron oxide nano- particles. Polymers have traditionally been considered as excellent host matrices for composite materials and sev- eral advanced polymer composites have been synthesized with a wide variety of fillers like metals, semiconductors, carbon nanotubes, and magnetic nanoparticles. This is not surprising if one takes into account the main positive fea- tures of polymers such as chemical inertia, lightweight, mechanical strength, and dielectric tenability that can be all exploited in combination with magnetic and optical properties of nanoparticles to deliver high performance multifunctional materials. To this purpose, there is a prac- tical need to disperse the nanoparticles in nonmagnetic media that can be easily processed and polymers, espe- cially thermoplastics, are very well suited. These attrac- tive characteristics are particularly of interest to recent potential applications of magnetic nanocomposites that include suppression of electromagnetic interference (EMI) [15–17] or strain sensing capabilities [18, 19]. In these applications, materials possessing magnetic properties Correspondence to: I. Bavasso; e-mail: irene.bavasso@uniroma1.it DOI 10.1002/pc.24727 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2018 Society of Plastics Engineers POLYMER COMPOSITES—2018