Synthesis and physico-chemical study of polyester polyol of epoxy resin of 1, 1’-bis (3-methyl-4-hydroxy phenyl) cyclohexane and ricinoleic acid and its polyurethanes with polyethylene glycol

Abstract

Cardo polyester polyol (acid value, 2.14; hydroxyl value, 911 mg KOH/g) has been synthesized by reacting epoxy resin of 1,1’-bis (3-methyl-4-hydroxy phenyl) cyclohexane (EE = 436) and ricinoleic acid (8.94 g) by using triethyl amine (0.5 g) as a catalyst and 1,4-dioxane as a solvent at reflux temperature for 6h. Cardo polyester polyol-TDI based copolyurethanes have been synthesized by reacting polyol (3.0 g) and TDI (0.9 g) in MEK at room temperature by using 20% and 30% PEG- 400 on the basis of polyol weight. PU-20 and PU-30 films were cast by controlled evaporation of MEK. The formation of polyol and copolyurethanes are supported by FTIR spectral data. Densities of PU-20 (1.2379 g/cm³) and PU-30 (1.2016 g/ cm³) are determined by floatation method at room temperature by using CCl₄₋ n- hexane system. Density decreased with PEG-400 concentration due to increase in intrinsic volume of the repeating unit. Tensile strength, electric strength and volume resistivity of both co polyurethanes decreased with increasing concentration of PEG-400 due to presence of soft and hard segments in polymer chain. PU-20 and PU-30 remained unaffected in pure water and 10% NaCl solution and showed moisture uptake tendency in acidic and alkaline atmosphere. Max. moisture uptake, observed within 24-48h, is 4.7-15% in 10% each of HCl, H₂SO₄ and HNO₃ and 8.7-14.2 % in 10% each of NaOH and KOH solutions. PU-30 has much low water absorption tendency as compared to PU-20 due to increasing PEG-400 concentration. PU-20 and PU-30 are thermally stable up to about 190-198°C and involved three-step degradation kinetics. No effect of PFG-400 was observed on thermal properties of co polyurethanes. For PU-20, T₀, T₁₀ and T₅₀ are 190, 225.1 and 362.6°C, while for PU-30 they are 198, 235.5 and 369.0°C, respectively. The decomposition ranges are 190-304, 342-440,472-540 and 198-307, 350-430, and 448-5900C, respectively for PU-20 and PU-30. The excellent hydrolytic stability and fairly good thermo-mechanical and electrical properties of PU-20 and PU-30 signify their industrial importance as coating and adhesive materials.