Abstract
The purpose of this study was to improve toughness of inherently very brittle polylactide (PLA) without sacrificing strength and thermal properties, so that biopolymer PLA could be used in engineering applications. For this purpose, PLA was blended with various amounts of two different thermoplastic elastomers; TPU (petroleum-based thermoplastic polyurethane) and TPE (bio-based thermoplastic polyester). Melt blending and specimen shaping were achieved by using a twin-screw extruder and injection molder, respectively. SEM analysis indicated that TPU and TPE were immiscible forming fine and uniform round domains in the PLA matrix. It was revealed that rubber-toughening mechanisms of TPU and TPE were very effective. For instance, using only 10 phr of TPU or TPE increased Charpy impact toughness of PLA more than 300 %, while increases in fracture toughness (KIC and GIC) values of PLA were as much as 35 % and 130 %, respectively. Other mechanical tests (tension, flexure, hardness) and thermal analyses (DSC) revealed that there were no significant detrimental effects of using 10 phr TPU or TPE on the engineering performance of PLA.
References
Baouz, T., Rezgui, F. and Yilmazer, U., “Ethylene-Methyl Acrylate-Glycidyl Methacrylate Toughened Poly(lactic acid) Nanocomposites”, J. Appl. Polym. Sci., 128, 3193–3204 (2012) 10.1002/app.38529Search in Google Scholar
Bitinis, N., Verdejo, R., Cassagnau, P. and Manchado, M. A., “Structure and Properties of Polylactide/Natural Rubber Blends”, Mater. Chem. Phys., 129, 823–831 (2011) 10.1016/j.matchemphys.2011.05.016Search in Google Scholar
Feng, F., Ye, L., “Morphologies and Mechanical Properties of Polylactide/Thermoplastic Polyurethane Elastomer Blends”, J. Appl. Polym. Sci., 119, 2778–2783 (2011) 10.1002/app.32863Search in Google Scholar
Fischer, E. W., Sterzel, H. J. and Wegner, G., “Investigation of Structure of Solution Grown Crystals of Lactide Copolymers by Means of Chemical Reactions”, Colloid Polym. Sci., 251, 980–990 (1973) 10.1007/978-3-642-47050-9_24Search in Google Scholar
Han, J., Huang, H., “Preparation and Characterization of Biodegradable Polylactide/Thermoplastic Polyurethane Elastomer Blends”, J. Appl. Polym. Sci., 120, 3217–3223 (2011) 10.1002/app.33338Search in Google Scholar
Hong, H., Wei, J., Yuan, Y., Chen, F., Wang, J., Qu, X. and Liu, C., “A Novel Composite Coupled Hardness with Flexibleness-Polylactic Acid Toughen with Thermoplastic Polyurethane”, J. Appl. Polym. Sci., 121, 855–861 (2011) 10.1002/app.33675Search in Google Scholar
Ishida, S., Nagasaki, R., Chino, K., Dong, T. and Inoue, Y., “Toughening of Poly(L-lactide) by Melt Blending with Rubbers”, J. Appl. Polym. Sci., 113, 558–566 (2009) 10.1002/app.30134Search in Google Scholar
Jiang, J., Su, L., Zhang, K. and Wu, G., “Rubber-Toughened PLA Blends with Low Thermal Expansion”, J. Appl. Polym. Sci., 128, 3993–4000 (2012) 10.1002/app.38642Search in Google Scholar
Kaynak, C., Meyva, Y., “Use of Maleic Anhydride Compatibilization to Improve Toughness and Other Properties of Polylactide Blended with Thermoplastic Elastomers”, Polym. Adv. Technol., 25, 1622–1632 (2014) 10.1002/pat.3415Search in Google Scholar
Li, Y., Liu, L., Shi, Y., Xiang, F., Huang, T., Wang, Y. and Zhou, Z., “Morphology, Rheological, Crystallization Behavior, and Mechanical Properties of Poly(L-lactide)/Ethylene-co-Vinyl Acetate Blends with Different VA Contents”, J. Appl. Polym. Sci., 121, 2688–2698 (2011) 10.1002/app.33581Search in Google Scholar
Yeh, J., Tsou, C., Li, Y., Xiao, H., Wu, C., Chai, W., Lai, Y. and Wang, C., “The Compatible and Mechanical Properties of Biodegradable Poly(lactic acid)/Ethylene Glycidyl Methacrylate Copolymer Blends”, J. Polym. Res, 19, 9766–9780 (2012) 10.1007/s10965-011-9766-4Search in Google Scholar
Zaman, H. U., Song, J. C., Park, L., Kang, I., Park, S., Kwak, G., Park, B. and Yoon, K., “Poly(lactic acid) Blends with Desired End Use Properties by Addition of Thermoplastic Polyester Elastomer and MDI”, Polym. Bull., 67, 187–198 (2011) 10.1007/s00289-011-0448-5Search in Google Scholar
Zhang, K., Ran, X., Wang, X., Han, C., Han, L., Wen, X., Zhuang, Y. and Dong, L., “Improvement in Toughness and Crystallization of Poly(L-lactic acid) by Melt Blending with Poly(epichlorohydrin-co-ethylene oxide)”, Polym. Eng. Sci., 51, 2370–2380 (2011) 10.1002/pen.22009Search in Google Scholar
Zhang, H., Liu, N., Ran, X., Han, C., Han, L., Zhuang, Y. and Dong, L., “Toughening of Polylactide by Melt Blending with Methyl Methacrylate-Butadiene-Styrene Copolymer”, J. Appl. Polym. Sci., 125, 550–561 (2012) 10.1002/app.36952Search in Google Scholar
© 2015, Carl Hanser Verlag, Munich