maryam afshar - Department ofPolymer Processing, Iran Polymer and Petrochemical Institute, Tehran, Iran
jalil morshedian - Department ofPolymer Processing, Iran Polymer and Petrochemical Institute, Tehran, Iran
shervin ahmadi - Department ofPolymer Processing, Iran Polymer and Petrochemical Institute, Tehran, Iran

High energy radiation can be dangerous to human life depending on its energy. The three main rules for protection against the hazards of radiation are time, shielding and distance. Spending the shortest amount of time possible around the radiation source, staying as far away as possible from it, and using a shield between ourselves and the source can reduce thehazardous affects [1, 2]. The intensity of damage depends on the type of radiation, energy of radiation, absorbed dose, exposure time, etc.; unfortunately, thewide range of applications which involved these types of high energy radiation, such as x-ray and gammaray, is large. X-ray and gamma-ray are radiation sources found in numerous industries such as aerospace, medical, nuclear reactors, securities and agriculture. Our interest is in the medical industry, particularly radiology, where we are mainly dealing with x-ray and gamma ray. How Since high energy radiations can easily penetrate the human body, highdensity materials can be used for radiation shielding [3]. Generaly, lead and lead compounds are used for high-energy radiation shielding. However, lead is toxic and aprons are very heavy for personal shielding and also have disposal problems [4]. Therefore, polymer-based composites are particularly interesting candidates as radiation shielding materials for varied reasons such as lightness, environmental-friendliness, non-toxicity and flexibility [5]. Numerous experimental investigations and theoretical studies have reported the use of a variety of shielding materials for attenuation or absorption of undesired radiations, a few of which are mentioned below. The presence of wolfram metal powder in a styrenebutadiene- styrene copolymer matrix created a new high energy radiation shielding material [6]. In another work, prepared high density polymer-wolfram composites were studied and showed low x-ray transmittance [7]. Another study has been done on the radiation shielding provided by recycled agricultural fiber and industrial plastic wastes with lead oxide and boron carbide produced as composite material. In that study, B4C was used to absorb the neutron radiation [8]. Moreover, the presence of iodine monobromide (IBr) in graphite composites showed efficient shielding against x-ray radiation [9], and the presence of CNT has been proven to improve the resistance of PMMA against high-energy radiation [10]. 0.5 weight percentage of single-walled CNT in poly (4-methyl-1- pentene) (PMP) has shown an increase in electromagnetic radiation resistance [11]. It has been seen that concrete containing polystyrene and boron oxide can improve neutron shielding [12]. The presence of borosilicate has been shown to compensate for LDPE weakness of at high temperature and pressure such as that used for shielding in the spacecraft industry [13]. It has been proven that 2 weight percentage of boron nitride in HDPE can improve neutron-beam shielding [14]. Studies have shown that nano-sized boron carbide (B4C) and boron nitride (BN) powder melt blended with HDPE enhanced thermal neutron attenuation [15]. The purpose of this study is to evaluate whether the developed non-lead polymer composites are effective at blocking diagnostic x-ray radiation. We focused on high-density PE composites containing tungsten, molybdenum disulfide and boron carbide powders separately, and the effect of these particles, mainly on x-ray radiation attenuation, is investigated. The above particulate fillers contain three elements from the 6th and 13th group of the Mendeleev Table, which could be appropriate radiation shields either with a high atomic number or lamellar structure. As the type, structure and size of the filler are important factors in radiation absorption, tungsten metallic powder with its high atomic number and spherical shape, molybdenum disulfide as another high atomic number-metal compound with a lamellar shape, and boron carbide as a compound of a reported effective semi-metal with lamellar shape were chosen to be studied as dispersions in a fiber forming grade high density polyethylene.

radiation attenuation,dispersion rheology ,metallic compounds,radiology ,x-ray,gamma-ray