Preparation and Study on the Properties of LDPE-Thermoplastic Starch Blends; Part I: Effect of PE-g-MA on the Mechanical Properties and Flow Behavior

Document Type : Research Article


Polymer Group, Chemical Engineering Department, Isfahan University of Technology, P.O. Box 84156-83111 Isfahan, I.R. IRAN


In this work, effect of maleic anhydride grafted- LDPE (PE-g-MA) on the mechanical, morphology and flow behavior of biodegradable LDPE-thermoplastic corn starch (TPS) blends were investigated. TPS was prepared by mixing neat starch and glycerol (35wt. %) at room temperature. The mixture then was melt-compounded using an internal mixer at 140oC, rotor speed of 60 rpm for 8 minutes. LDPE-TPS blends containing different contents of TPS (0-40wt. %) with (3wt. %) and without the addition of PE-g-MA, were prepared using a single-screw extruder. Surface morphology of the prepared blends was investigated by Scanning Electron Microscopy (SEM). Also, mechanical properties and flow behavior of the prepared samples were carried out by means of related standard test methods. Scanning electron micrographs of the samples show improvement in dispersion of the starch particles in LDPE matrix in the presence of PE-g-MA as a compatibilizer. Also, the results of mechanical properties indicate that as TPS concentration increases, the ultimate tensile strength, elongation at break, Young’s modulus and relative impact strength of the blends decrease. However, the compatibilized blends represent higher mechanical properties than the blends without any compatibilizer. Furthermore, the addition of starch to LDPE decreases the melt flow index values of the samples and subsequently increases their apparent viscosity.The results of rheological tests also indicate that as shear rate increases, the apparent viscosity of the samples decreases (shear thinning).


Main Subjects

[1] Gupta A., Sharma M., Formulation and Characterization of Biodegradable Packaging Film Derived from Potato Starch & LDPE Grafted with Maleic Anhydride-LDPE Composition, J. Polym. Environ.,18, p.484 (2010). 
[2] Prachayawarakorn J., Sangnitidej P., Boonpasith P., Properties of Thermoplastic Rice Starch Composites Reinforced by Cotton Fiber or Low-Density Polyethylene, Carbohyd. Polym., 81, p. 425 (2010).
[3] Elanmugilan M., Sreekumar P.A., Singha N.K., Al-Harthi M.A., De. S.K., Natural Weather, Soil Burial and Sea Water Ageing of Low-Density Polyethylene: Effect of Starch/Linear Low-Density Polyethylene Masterbatch, J. Appl. Polym. Sci.,129, p. 449 (2013).
[4] Liu X., Yu L., Xie F., Petinakis E., Sangwan P., Shen S., Dean K., New Evidences of Accelerating Degradation of Polyethylene by Starch, J. Appl. Polym. Sci.,130, pp.2282 (2013).
[5] Griffin G.J.L., Starch Polymer Blends, Polym.  Degrad. Stab., 45, p. 241 (1994).
[6] Liu X., Xie F., Yu L., Chen L., Li. L.,Thermal Processing of Starch-Based Polymers, Prog. Polym. Sci., 34, p. 1348 (2009).
[7] Girija B.G., Sailaja R.R.N., Low-Density Polyethylene/Plasticized Tapioca Starch Blends with the Low-Density Polyethylene Functionalized with Maleate Ester: Mechanical and Thermal Properties, J. Appl. Polym. Sci., 101, p. 1109 (2006.)
[8] Fang J.M., Fowler P.A., Tomkinson J., Hill C.A.S., The Preparation and Characterisation of a Series of Chemically Modified Potato Starches, Carbohyd. Polym., 47, p. 245 (2002).
[9] Yoo S.I., Lee T.Y., Yoon J.S., Lee I.M., Kim M.N., Lee H.S., Interfacial Adhesion Reaction of Polyethylene and Starch Blends Using Maleated Polyethylene Reactive Compatibilizer, J. Appl. Polym. Sci., . 83, p. 767 (2002).
[10] Cerclé C., Sarazin P., Favis B.D., High Performance Polyethylene/Thermoplastic Starch Blends Through Controlled Emulsification Phenomena, Carbohyd. Polym., 92, p. 138 (2013).
[11] Matzinos P., Bikiaris D., Kokkou S., Panayiotou C., Processing and Characterization of LDPE/Starch Products, J. Appl. Polym. Sci., 79, p. 2548 (2001).
[12] Gupta A., Sharma M., Characterization of Biodegradable Packaging Films Derived from Potato Starch and LDPE Grafted with Maleic Anhydride–LDPE Composition. Part-II, J. Polym. Environ., 18, p. 492 (2010).
[13] Sailaja R.R.N., Chanda M., Use of maleic Anhydride-Grafted Polyethylene as Compatibilizer for HDPE–Tapioca Starch Blends: Effects on Mechanical Properties, J. Appl. Polym. Sci., 80, p. 863 (2001).
[14] Sabetzadeh M., Bagheri R., Masoomi M.,Effect of Corn Starch Content in Thermoplastic Starch/Low-Density Polyethylene Blends on Their Mechanical and Flow Properties, J. Appl. Polym. Sci., 126, p. E63 (2012).
[15] Majid R.A., Ismail H., Taib R.M., Effects of PE-g-MA on Tensile Properties, Morphology and Water Absorption of LDPE/Thermoplastic Sago Starch Blends, Polym. Plast. Technol. Eng., 48, p. 919 (2009).
[16] Bikiaris D., C. Panayiotou C., LDPE/Starch Blends Compatibilized with PE-g-MA Copolymers, J. Appl. Polym. Sci., 7,  p. 1503 (1998). 
[17] Liu W., Wang Y.J., Sun Z., Effects of Polyethylene-Grafted Maleic Anhydride (PE-g-MA) on Thermal Properties, Morphology, and Tensile Properties of Low-Density Polyethylene (LDPE) and Corn Starch Blends, J. Appl. Polym. Sci., 88, p. 2904 (2003).
[18] Sailaja R.N.N., Chanda M., Use of Maleic Anhydride-Grafted Polyethylene as Compatibilizer for Polyethylene-Starch Blends: Effects on Mechanical Properties, J. Polym. Mater., 17, p. 165 (2000).
[19] Wang Y.J., Liu W., Sun Z., Effects of Glycerol and PE-g-MA on Morphology, Thermal and Tensile Properties of LDPE and Rice Starch Blends, J. Appl. Polym. Sci.,92, p. 344 (2004).
[20] Jang B.C., Huh S.Y., Jang J.G., Bae Y.C., Mechanical Properties and Morphology of the Modified HDPE/Starch Reactive Blend, J. Appl. Polym. Sci., 82, pp.3313 (2001).
[21] Chandra R., Rustgi R., Biodegradation of Maleated Linear Low-Density Polyethylene and Starch Blends, Polym. Degrad. Stab., 56, pp.185 (1997).
[22] IzaM., Bousmina M., Jérôme R.,Rheology of Compatibilized Immiscible Viscoelastic Polymer Blends, Rheo. Acta., 40, pp.10 (2001).
[23] Bagheri R., Effect of Processing on the Melt Degradation of Starch-Filled Ppolypropylene, Polym. Int., 48, pp.1257 (1999).