Ibanga O. Isaac^*, Edet W. Nsi

Show more
Department of Chemistry, Akwa Ibom State University, Uyo, Nigeria.
Show less

Abstract: Six grades of biopolymers formulated to have oil content of 40% (M1), 50% (M2), and 60% (M3) melon seed oil (MESO) and 40% (C1), 50% (C2), and 60% (C3) cottonseed oil (COSO) respectively, were prepared with phthalic anhydride, and glycerol using alcoholysis-polycondensation process. The extend of polycondensation was monitored by determining the acid value of aliquots of the reaction mixture at various intervals of time. Molecular weight averages and polydispersity index (PDI) of the finished alkyds were determined by Rast method and end-group analysis. Molecular weight averages and PDI vary with differences in oil length of the alkyds, with samples M2 and C2 respectively exhibiting the highest PDI. Molecular weight average obtained from end-group analysis and those determined by Rast method in brackets are 1338.92 (597.00), 982.33 (696.25), 1316.09 (754.03), and 1160.57 (448.13), 765.96 (583.57), 1049.92 (696.25) for samples M1, M2, M3 and C1, C2, C3 respectively. Number molecular weight averages calculated from end-group analysis are larger than those obtained by Rast method for both MESO and COSO alkyds and seem to grossly overestimate their molecular weights. The mode of variation of these properties indicates that the synthesis of MESO and COSO alkyds are complex. Correlation of PDI with the quality of the finished alkyds shows that the higher the PDI value the better the quality of the alkyd. Performance properties such as rate of drying, film hardness and resistance to chemicals were optimum at 50% oil length for both triglyceride oil alkyds.

Keywords: Biopolymers, End-Group Analysis, Molecular Weight Averages, Polydispersity Index, Rast Method

Cite this paper: Isaac, I. and Nsi, E. (2015) Studies in Molecular Weight Determination of Cottonseed and Melon Seed Oils Based Biopolymers. Advances in Chemical Engineering and Science, 5, 43-50. doi: 10.4236/aces.2015.51005.

References

[1]   Isaac, I.O. and Ekpa, O.D. (2014) Comparative Study on the Kinetics of the Preparation of Melon Seed and Cottonseed Oils Based Biopolymers. American Journal of Polymer Science, 4, 7-15.

[2]   Uzoh, C.F., Onukwuli, O.D., Odera, R.S. and Ofochebe, S. (2013) Optimization of Polyesterification Process for Production of Palm Oil Modified Alkyd Resin Using Response Surface Methodology. Journal of Environmental Chemical Engineering, 1, 777-785.
http://dx.doi.org/10.1016/j.jece.2013.07.021

[3]   Ling, J.S., Mohammed, I.A., Ghazali, A. and Khairuddean, M. (2014) Novel Poly (Alkyd-Urethane)s from Vegetable Oils: Synthesis and Properties. Industrial Crops and Products, 52, 74-84.
http://dx.doi.org/10.1016/j.indcrop.2013.10.002

[4]   Aigbodion, A.I. and Okieimen, F.E. (1996) Kinetics of the Preparation of Rubber Seed Oil Alkyds. European Polymer Journal, 32, 1105-1108.
http://dx.doi.org/10.1016/0014-3057(96)00053-5

[5]   Okieimen, F.E. and Aigbodion, A.I. (1997) Studies in Molecular Weight Determination of Rubber Seed Oil Alkyds. Industrial Crops and Products, 6, 155-161.
http://dx.doi.org/10.1016/S0926-6690(96)00209-9

[6]   Nagata, T. (1969) Cooking Schedule of Alkyd Resin Preparation—Part II. Effect of Cooking Schedule on Molecular Weight Distribution of Alkyd Resin. Journal of Applied Polymer Science, 13, 2601-2619.
http://dx.doi.org/10.1002/app.1969.070131208

[7]   Bobalek, E.G., Moore, E.R., Levy, S.S. and Lee, C.C. (1964) Some Implications of Gel Point Concept on the Chemistry of Alkyd Resins. Journal of Applied Polymer Science, 8, 625-657.
http://dx.doi.org/10.1002/app.1964.070080207

[8]   Aigbodion, A.I. and Pillai, C.K. (2001) Synthesis and Molecular Weight Characterization of Rubber Seed Oil-Modified Alkyd Resins. Journal of Applied Polymer Science, 79, 2431-2438.
http://dx.doi.org/10.1002/1097-4628(20010328)79:13<2431::AID-APP1050>3.0.CO;2-A

[9]   Flory, P.J. (1953) Principles of Polymer Chemistry. Cornell, Ithaca, New York.

[10]   Isaac, I.O. and Ekpa, O.D. (2013) Fatty Acid Composition of Cottonseed Oil and Its Application in Production and Evaluation of Biopolymers. American Journal of Polymer Science, 3, 13-22.

[11]   Ekpa, O.D. and Isaac, I.O. (2013) Fatty Acid Composition of Melon (Colocynthis vulgaris Shrad) Seed Oil and Its Application in Synthesis and Evaluation of Alkyd Resins. IOSR Journal of Applied Chemistry, 4, 30-41.
http://dx.doi.org/10.9790/5736-0443041

[12]   Flory, P.J. (1941) Molecular Size Distribution 3-Dimensional Polymers I: Gelation. Journal American Chemical Society, 63, 3083-3090.
http://dx.doi.org/10.1021/ja01856a061

[13]   Stockmayer, W.H. (1952) Molecular Distribution in Condensation Polymerization. Journal of Polymer Science, 9, 69-71.
http://dx.doi.org/10.1002/pol.1952.120090106

[14]   Furniss, B.S., Hannaford, A.J., Rogers, V., Smith, P.W.G. and Tatchel, A.R. (1978) Vogel’s Textbook of Practical Organic Chemistry. 4th Edition, ELBS & Longman, London.

[15]   Ekpa, O.D. and Isaac, I.O. (2009) Kinetic Studies on Polyesterification of Unsaturated Oils and Diacids in the Alcoholoysis Process. Research Journal of Applied Science, 4, 125-128.

[16]   Isaac, I.O. and Ekpa, O.D. (2013) Comparative Study on Solution Viscosity Properties of Cottonseed and Melon Seed Oils Based Biopolymers. American Journal of Polymer Science, 3, 23-34.

[17]   Onukwli, O.D. and Igbokwe, P.K. (2008) Production and Characterization of Castor Oil-Modified Alkyd Resins. Journal of Engineering & Applied Science, 3, 161-165.

[18]   Kienle, R.H., Van der Meulen, P.A. and Petke, F.E. (1939) The Polyhydric Alcohol-Polybasic Acid Reaction III: Further Studies of the Glycerol-Phthalic Acid Reaction. Journal of American Chemical Society, 61, 2258-2268.
http://dx.doi.org/10.1021/ja01878a001

[19]   Isaac, I.O. and Nsi, E.W. (2013) Influence of Polybasic Acid Type on the Physicochemical and Viscosity Properties of Cottonseed Oil Alkyd Resins. The International Journal of Engineering and Science, 2, 1-14.