International Journal of Scientific and Research Publications, Volume 8, Issue 10, October 2018 83 ISSN 2250-3153 http://dx.doi.org/10.29322/IJSRP.8.10.2018.p8213 www.ijsrp.org Effects of Internal Plasticization on the Physical and Mechanical Properties of Castor Oil - Based Polyurethane Foams A.K. Yusuf 1 , P.A.P. Mamza 2 , A.S. Ahmed 3 and U. Agunwa 4 1 Department of Chemistry, Al-Qalam University, Katsina 2 Department of Chemistry, Ahmadu Bello University, Zaria 3 Department of Chemical Engineering, Ahmadu Bello University, Zaria 4 National Research Institute for Chemical Technology (NARICT), Zaria DOI: 10.29322/IJSRP.8.10.2018.p8213 http://dx.doi.org/10.29322/IJSRP.8.10.2018.p8213 Abstract - Flexible castor oil-based polyurethane foams were produced by the one-shot method of foam synthesis. Foam formulation involved pure castor oil/castor oil modified with heptachloroheptadecane (HCHD), a novel C-17 chlorinated hydrocarbon internal plasticizer, 80:20 mixture of 2,4 - and 2,6 - toluene diisocyanate (TDI) at room temperature (30 - 35 0 C). Foam reaction took place in presence of stannous octoate and dimethylaminoethanol (DMAE) catalysts, methylene chloride (physical blowing agent) and silicone oil (surfactant). Isocyanate/polyol (NCO/OH) ratio was 1/1. Concentration of plasticizer used varied from 0.4 - 2.4 wt%. Foams obtained were tested for their physical and mechanical properties. Suggested mode of action and the influence of the incorporated internal plasticizer (HCHD) on these properties are discussed. Results indicate reduction in the density and compressive strength of the foams, but enhancement of their % creep recovery and water absorption as plasticizer concentration increased. These property changes suggest greater flexibility, extensibility and workability of foam. The most flexible foams were obtained at 2.4wt% concentration of the incorporated plasticizer. Areas of potential applicability or end-use of the new products are highlighted. Index Terms - castor oil; plasticizer; flexible foam; properties. INTRODUCTION Polyurethanes (PUs) are polymers containing the urethane linkage (-NH-CO-O-) in the main chain. Polyurethane foams (PUFs) can be produced by reacting a polyol with an excess of organic polyisocyanate (in presence of catalysts and other additives) according to the generalized PU reaction. R (OH)n + R 1 -(N=C=O)n R l – ( NH.CO-O) n -R (1) polyol polyisocyanate polyurethane (where n > 2) The replacement of petroleum-based polyols or petropolyols such as polyether and polyester polyols with polyols derived from renewable materials of plant origin in the synthesis of PUFs has resulted in cheaper, safer, more environment friendly products with excellent thermal stability and oxidation resistance. Superior thermal stability and oxidation resistance of plant oil polyols over petropolyols are believed to be due to higher hydrocarbon content in the former (Javni et al., 2000, Petrovic et al., 2005; Badri; 2012). In the adhesive industry, for instance, this innovation has yielded degradable castor oil-based PU adhesives (Somani et al., 2003; Gayki et al., 2015). However, most PU products obtained from unmodified triacyglycerol (TAG)-based oil polyols (chiefly soybean, castor, palm and canola oil polyols) are reported to be crosslinked materials or thermosets (Guo et al., 2000; Zlatanic et al.; 2002; Petrovic et