Studies on the blends of cardanol-based epoxidized novolac resin and CTPB Archana Devi, Deepak Srivastava * Department of Plastic Technology, H.B. Technological Institute, Kanpur 208 002, Uttarpradesh, India Received 15 January 2007; received in revised form 27 February 2007; accepted 2 March 2007 Available online 12 March 2007 Abstract Cardanol-based novolac-type phenolic resins were synthesized with different mole ratios of cardanol-to-formaldehyde, viz., 1:0.6, 1:0.7, and 1:0.8. These novolac resins were epoxidized with molar excess of epichlorohydrin at 120 °C in basic medium. The epoxidized novolac resins were, separately, blended with different weight ratios of carboxyl-terminated poly- butadiene liquid rubber ranging between 0–25 wt% with an interval of 5 wt%. All the blends were cured at 150 °C with 40 wt% polyamide. The formation of various products during the curing of blend samples has been studied by Fourier- transform infra-red spectroscopic analysis. The tensile strength and elongation-at-break of the cured samples increased up to 15 wt% in the blend and decreased thereafter. This blend sample was also found to be most thermally stable system. The blend morphology, studied by scanning electron microscopy analysis, was finally correlated with the structural and property changes in the blends. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Cardanol-based epoxidized novolac resin; Carboxyl-terminated polybutadiene (CTPB) liquid rubber; Blends; Polyamide; Mechanical, thermal, chemical and morphological properties 1. Introduction Cashew nut shell liquid (CNSL), an agricultural byproduct abundantly available in the country, is one of the few major and economic sources of nat- urally occurring phenols and can be regarded as a versatile and valuable raw material for polymer pro- duction. Cardanol, a natural alkyl phenol from CNSL, a potential natural source for biomonomers, cannot even today be said to have found its niche in terms of an appropriate industrial applications. By far the greatest amount of work on polymeric mate- rials derived from CNSL or cardanol have been with their use in the manufacture or modification of phenolic resins [1–5]. The phenolic nature of the material makes it possible to react under a variety of conditions to form both base catalyzed resoles and acid catalyzed novolacs. The cardanol based novolac-type phenolic resins may further be modified by epoxidation with epichlorohydrin to duplicate the performance of such phenolic-type novolacs [1]. Having several outstanding character- istics, epoxy resins show low impact resistance in their cured state [6–11] which limits the applications 0014-3057/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2007.03.006 * Corresponding author. E-mail address: deepak_sri92@rediffmail.com (D. Srivastava). European Polymer Journal 43 (2007) 2422–2432 www.elsevier.com/locate/europolj EUROPEAN POLYMER JOURNAL