Canadian Journal on Scientific & Industrial Research Vol. 2, No. 3, March 2011 95 Modification of Tensile and Impact Properties of Crosslinked Rubber Toughened Nanocomposites via Electron Beam Irradiation N.A. Jamal, H. Anuar and S.B.A. Razak Abstract - Enhancing the tensile and impact properties of high density polyethylene (HDPE)/ethylene propylene diene monomer (EPDM) matrix is the main target of developing nanocomposite. The nanocomposite system was first prepared via melt intercalation method with different organophilic montmorillonite (OMMT) loadings. Electron beam (EB) irradiation was applied as a crosslinking agent for modification of tensile and impact properties of HDPE/EPDM matrix and HDPE/EPDM filled OMMT systems. The effectiveness of EB irradiation technique were then compared with control one (uncrosslinked system) and analyzed based on the tensile and impact tests as well as morphological examination. The tensile and impact tests revealed that control and EB irradiated systems had attained the optimum tensile and impact properties at 4 vol% OMMT content. EB irradiated system at dose rate of 100 kGy showed excellent in tensile and impact properties with the highest crosslinking degree which were proved by gel content analysis. X-ray diffraction (XRD) analysis confirmed the existence of delamination structure with EB irradiation technique based on the disappearance of characteristic peak. The degree of delamination was further investigated by transmission electron microscope (TEM). Key Words - Tensile properties; Impact property; Organophilic montmorillonite; Electron beam irradiation; Gel content I. INTRODUCTION Studies on polymer matrix filled nano filler have been widely investigated due to its outstanding properties. These polymer layered silicate (PLS) nanocomposites can attain a certain degree of stiffness, strength and barrier properties with far less ceramic content than comparable glass or common inorganic reinforced polymers [1-4]. Although other solids can be used, the most common reinforcements currently used to make nanocomposites are natural silicates, such as mica, montmorillonite, kaolinite, saponite and hectorite [4]. As most nano filler is hydrophilic in nature, they are known to be incompatible with hydrophobic polymer matrix. A general approach to alleviate such phenomenon is by the introduction of crosslinking agent or so called compatibilizer agent. Most researchers introduced compatibilizer agent by means the use of chemical agents such as maleic anhydride grafted polymer (MA-g) plastic resin, silane agent and so on [2-6]. In the current study, instead of using chemical agent, physical crosslinking agent by means of electron beam irradiation (EB) has been introduced to enhance the compatibility between the polymer matrix and nano filler. EB irradiation offers similar or even better advantages as compared to crosslinking agent by means of chemical agent. The property enhancements achieved include improved mechanical and properties, increased chemical and solvent resistance. Chain crosslinking and scission are the two reactions that occur during EB processing of polymers. Polymers typically undergo simultaneous scission and crosslinking, but in most cases with one or the other clearly predominating [7-10]. Crosslinking is the intermolecular bond formation of polymer chain. The degree of crosslinking is proportional to the radiation dose [8, 9]. On other word, polymer chains of different component are connected to one another by the crosslinking bonds to form a rigid three dimensional network. Much works have been done on radiation crosslinking of uncrosslinked polymers and crosslinking of various rubbers and plastics by electron beam irradiation [7-10]. In contrast, scission is the opposite process of crosslinking in which the rupturing of carbon-carbon bond occurs. Scission reduces crosslinking efficiency and degrades the properties of polymers (chemical resistance, mechanical and thermal properties). Polymer matix for the current system consists of blending high density polyethylene (HDPE) and ethylene propylene diene monomer (EPDM) at the ratio of 70% of HDPE to 30% of EPDM. Different clay loadings are varied between 2, 4, 6 and 8 vol% for the development of nanocomposite system. Therefore, the current study aims to vary and highlight the interest of EB irradiation technique for HDPE/EPDM, where unfilled composites and nanocomposites were prepared with different irradiation doses rate between 50, 100, 150 and 200 kGy. The results obtained for the EB irradiated system were then compared with control system in order to determine the optimum system. II. EXPERIMENTAL DESIGN A. Materials Selection Homopolymer high density polyethylene (HDPE) (Melt index 3-6 g/10min, density 900 kg/cm 3 ) supplied by Cementhai Chemicals Group, Thailand and Ethylene