Synthesis and properties of cardanol‐based epoxidized novolac resins modified with carboxyl‐terminated butadiene–acrylonitrile copolymer

Abstract

Cardanol-based, novolac-type phenolic resins were synthesized with a cardanol-to-formaldehyde molar ratio of 1 : 0.7 with different dicarboxylic acid catalysts, including oxalic and succinic acids. These novolac resins were epoxidized with a molar excess of epichlorohydrin at 120 C in a basic medium. The epoxidized novolac resins were separately blended with different weight ratios of carboxyl-terminated butadiene-acrylonitrile copolymer (CTBN) ranging between 0 and 20 wt % with an interval of 5 wt %. All of the blends were cured at 120 C with a stoichiometric amount of polyamine. The formation of various products during the synthesis of the cardanol-based novolac resin and epoxidized novolac resin and the blending of the epoxidized novolac resin with CTBN was studied by Fourier transform infrared spectroscopy analysis. Furthermore, the products were also confirmed by proton nuclear magnetic resonance and matrix-assisted laser desorption/ionization time-offlight mass spectroscopy analysis. The molecular weights of the prepared novolacs and their epoxidized novolac resins were determined by gel permeation chromatography analysis. The blend samples, in both cases, with 15 wt % CTBN concentrations showed the minimum cure times. These blend samples were also the most thermally stable systems. The blend morphology, studied by scanning electron microscopy analysis, was, finally, correlated with the structural and property changes in the blends.

A chemical platform approach on cardanol oil: from the synthesis of building blocks to polymer synthesis

“…Hence, it was used in direct polymerization (Kim et al, 2005), as a polyol for the synthesis of new polyurethanes (Suresh et al, 2005), in polyester formulations (Lespinasse et al, 2011), in thermosets (such as Novolac) (Yadav et al, 2009;Huong et al, 1996), in vinyl ester networks (Sultania et al, 2010) and also in epoxy networks modification (Unnikrishnan et al, 2008).…”

Process modeling, optimization and analysis of esterification reaction of cashew nut shell liquid (CNSL)-derived epoxy resin using response surface methodology

“…Cardanol, like phenol, can be condensed with active hydrogen containing compounds such as formaldehyde to yield a series of phenolic resins, for instance, base-catalyzed resoles and acid-catalyzed novolacs [1][2][3][4][5][6][7][8][9]. The cardanol-based novolac-type phenolic resins may be modified to develop epoxy resins with epichlorohydrin to enhance the performance of such resins in various fields [10][11][12][13]. The introduction of unsaturation at the end of the epoxy resin backbone by the reaction with acid functional acrylic/methacrylic monomer can produce an eco-friendly vinyl ester resin system.…”

New biobased epoxy materials from cardanol

“…Cardanol was already extensively studied for material synthesis, particularly by Wadgaonkar and coworkers [16,17], through direct polymerization [18], as a polyol in new polyurethanes [19], in polyester compositions [20], with partial or total substitution of phenol in thermoset resins such as Novolac resins [9,21,22], vinyl esters [23] and also in epoxy resins modification [24]. But few works reported the epoxidation of cardanol for the synthesis of new epoxy resins.…”