Effect of Talc on the Properties of Polypropylene/Ethylene/ Propylene/Diene Terpolymer Blends Mustafa O ¨ ksu ¨ z, 1 Mehmet Eroglu, 2 Hu ¨ seyin Yıldırım 3 1 Technical Education Faculty, Marmara University, 34722 Goztepe, Istanbul, Turkey 2 Department of Metallurgical and Materials Engineering, Engineering Faculty, Fırat University, 23119, Elazig, Turkey 3 Department of Chemistry, Yıldız Technical University, 34210 Esenler, I ˙ stanbul, Turkey Received 15 March 2005; accepted 5 October 2005 DOI 10.1002/app.23699 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: In the present study, the effect of talc content on the mechanical, thermal, and microstructural properties of the isotactic polypropylene (i-PP) and elastomeric ethyl- ene/propylene/diene terpolymer (EPDM) blends were in- vestigated. In the experimental study, five different talc concentrations, 3, 6, 9, 12, and 15 wt %, were added to i-PP/EPDM (88/12) blends to produce ternary composites. The mechanical properties such as yield and tensile strengths, elongation at break, elasticity modulus, izod im- pact strength for notch tip radius of 1 mm, and hardness with and without heat treatments and thermal properties, such as melt flow index (MFI), of the ternary composites have been investigated. The annealing heat treatment was carried out at 100°C for holding time of 75 h. From the tensile test results, an increased trend for the yield and tensile strengths and elasticity modulus was seen for lower talc contents, while elongation at break showed a sharp decrease with the addition of talc. In the case of MFI, talc addition decreased the MFI of i-PP/EPDM blends. It was concluded that, taking into consideration, mechanical prop- erties and annealing heat treatment, heat treatment has much more effect on higher yield and tensile strengths, elongation at break, elasticity modulus, impact strength, and hardness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3033–3039, 2006 Key words: poly(propylene) (PP); talc; EPDM; mechanical properties; heat treatment INTRODUCTION Particulate filled polymers have been a subject of in- creasing interest in both industry and research. Polypropylene (PP) has a good processability allowing to accept numerous types of natural and synthetic fillers. The incorporation of fillers such as kaolin, mica, talc, and calcium carbonate into thermoplastics is a common practice to reduce production costs and to improve the properties such as strength, stiffness, hardness, flexural modules, dimensional stability, crystallinity, electrical, and thermal conductivity. However, high filler additions may adversely affect the processability, ductility, and strength of compos- ites. The properties of the composites strongly depend on the interfacial adhesion between filler and matrix. In case the adhesion is strong at the interface of filler and matrix, the mechanical properties may in- crease. 1–10 Although PP has been used widely in a variety of application because of its advantages, such as low density, low cost, high softening points, and easy pro- cessing, it has low impact strength especially at low temperatures and this limits its application as an engi- neering thermoplastic. To improve the impact strength, various elastomers, such as ethylene–propylene– copol- ymer, ethylene–propylene– diene terpolymer (EPDM), and ethylene-vinyl acetate, were blended with PP. Among these elastomers, EPDM is considered as one of the most effective impact modifiers for PP. Al- though toughness strength is improved by blending elastomer, this results in deteriorating tensile strength and modulus. Therefore, numerous studies have been performed to improve the toughness, stiffness, and strength balance. Therefore, PP has been modified by different fillers and elastomers. The mechanical prop- erties of such ternary composites strongly depend on their composition and characteristic of the compo- nents and the phase morphology, and in particular relative dispersion of additive components. In the ter- nary composites containing both elastomer and rigid fillers, two different types in phase structure may occur, where elastomer and filler particles are dis- persed separately on the PP matrix or the rubber encapsulates fillers particles, resulting in a low mod- ulus interlayer between matrix and filler. 11–21 In the literature, there are some published studies relating to PP/elastomer/filler ternary compos- ites. 11–20 However, the effect of talc with heat treat- Correspondence to: M. O ¨ ksu ¨ z (moksuz@marmara.edu.tr). Contract grant sponsor: Commission of Scientific Re- search Projects of the University of Marmara (FEN 105/ 020603). Journal of Applied Polymer Science, Vol. 101, 3033–3039 (2006) © 2006 Wiley Periodicals, Inc.