POLYMER TESTING Polymer Testing 25 (2006) 562–567 Material Properties Fracture toughness of thermoplastic co-poly (ether ester) elastomer—Acrylonitrile butadiene styrene terpolymer blends P. Sivaraman a , L. Chandrasekhar a , V.S. Mishra a , B.C. Chakraborty a,Ã , T.O. Varghese b a Naval Materials Research Laboratory, (DRDO), Anand Nagar (PO), Ambernath, Maharashtra 421 506, India b Central Institute of Plastic Engineering and Technology (CIPET), Cherlapally, Hyderabad 500 051, India Received 14 January 2006; accepted 24 March 2006 Abstract Acrylonitrile butadiene styrene terpolymer (ABS) was blended with thermoplastic co-poly (ether ester) elastomer (COPE) in different weight ratios in a twin screw extruder. Fracture toughness of the blends as a function of COPE weight percentage was studied. Fracture toughness was investigated using the J-integral by locus method developed by Kim et al. [B.H. Kim, C.R. Joe, D.M. Otterson, Polym. Test. 8 (1989) 119]. The fracture toughness of the blend with 5 wt% shows higher fracture toughness than pure ABS. The correlation of the topology of the fracture surface with the fracture toughness of the blends was carried out. The physical properties of the blends were studied. The addition of COPE improves the impact property, while flexural modulus shows a slight increase when ABS is blended with COPE at low concentration. The SEM micrographs show three-phase morphology. r 2006 Elsevier Ltd. All rights reserved. Keywords: Polymer blends; Fracture toughness; Mechanical properties; Morphology 1. Introduction Acrylonitrile butadiene styrene terpolymer (ABS) is one of the most important rubber-toughened thermo- plastics, which is widely used due to its toughness and good surface gloss. ABS is a blend of styrene–acry- lonitrile copolymer and polybutadiene and can be further blended with other polymers to broaden the scope of possible applications. For instance, ABS is blended with PC to improve low temperature impact strength and heat resistance [1,2]. ABS/PVC blends have good flame retardency and impact strength [3,4]. ABS/PBT blends have good processability and improved chemical and heat resistance [5,6]. Reports on ABS blended with thermoplastic elastomers are scanty. The chemical and low- temperature properties are improved when ABS is blended with TPU [7]. In the present work we report the fracture toughness and mechanical properties of ABS/thermoplastic polyether ester copolymer elas- tomer (COPE). It is expected that properties of ABS with respect to toughness, processability and thermal stability will be enhanced due to the blending with COPE. Linear fracture mechanics that is used for brittle polymers is inadequate for ductile polymers. In ARTICLE IN PRESS www.elsevier.com/locate/polytest 0142-9418/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymertesting.2006.03.007 Ã Corresponding author. Tel.: +91 251 2620 608; fax: +91 251 2620 604. E-mail address: bikask05@rediffmail.com (P. Sivaraman).