This paper evaluated the effect of multiwall carbon nanotube (MWCNT) on the properties of PBT/PC blends. The nanocomposites were obtained by melt blending MWCNT in the weight percentages 0.15, 0.3, and 0.45？wt% with PBT/PC blends in a high performance corotating twin screw extruder. Samples were characterized by tensile testing, dynamic mechanical analysis, thermal analysis, scanning electron microscopy, and X-ray diffraction. Concentrations of PBT and PC are optimized as 80？:？20 based on mechanical properties. A small amount of MWCNT shows better increase in the thermal and mechanical properties of the blends of PBT/PC nanocomposite when compared to nanoclays or inorganic fillers. The ultimate tensile strength of the nanocomposites increased from 54？MPa to 85？MPa with addition of MWCNT up to 0.3% and then decreased.The tensile modulus values were increased to about 60% and the flexural modulus was more than about 80%. The impact strength was also improved with 20% PC to about 60% and with 0.15% MWCNT to about 50%. The HDT also improved from 127°C to 205°C. It can be seen from XRD result that the crystallinity of PBT is less affected by incorporating MWCNT. The crystallizing temperature was increased and the MWCNT may act as a strong nucleating agent. 1. Introduction Polyesters like PBT and PET are semicrystalline and possess high stiffness, hardness, dimensional stability, good bearing strength, good electrical properties, excellent flow characteristics, and good resistance to chemicals but have low impact strength. PC has excellent impact strength. Polymer blends are developed in an effort to meet cost/performance required in many engineering applications. In these blends, it is important to establish some level of interfacial adhesion between the components in order to achieve the necessary toughness. The required bonding is achieved in some commercial blends, for example, polybutylene terephthalate/polyethylene terephthalate (PBT/PET), polybutylene terephthalate/polycarbonate (PBT/PC), as a result of the partial miscibility between the blend components [1–5]. PC-PBT is useful for car bumpers, front ends by Bayer (trade name: Macro Blend). DSM also recently announced PC-PET blends. The PBT/PC finds use in many engineering applications like automotive body panels, in outdoor power, or recreational equipment, appliance housings, telecommunication, and so forth. The PC will improve the impact strength and elongation of PBT since PBT like PET has lower impact strength [6–8]. The various blends of PBT and the properties improvement are also given in [8].
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