Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 4 (2017) 6502–6511 www.materialstoday.com/proceedings 2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Science and Technology of the Emerging Materials. STEMa2016 Effect of modified eggshell powder on physical properties of poly(lactic acid) and natural rubber composites P. Somdee a,* , A. Hasook a a Department of Materials Engineering, Rajamangala University of Technology Isan, Nakhon Ratchasima, 30000 Thailand Abstract Physical properties of poly(lactic acid) (PLA), natural rubber (NR) and modified eggshell powder (MES) composites were analyzed. PLA, NR and MES were melt-blended using a twin screw extruder. NR content was varied from 3 to 10 wt.%, while MES content was varied between 1 and 7 wt.%. The mechanical properties, thermal properties and morphology of PLA composites were investigated. The results showed that the elongation at break when adding NR at 10 wt.% increased up to 33% compared to neat PLA. On the other hand, adding MES in PLA/NR decreased the elongation at break. By decreasing NR and increasing MES content, tensile strength at break decreased from 47 MPa to 6 MPa. Young’s modulus of PLA composites was higher than that of neat PLA by 12% when 3 wt.% NR and 7 wt.% MES were added. Moreover, the addition of 10 wt.% NR gave the composite with highest impact strength at 2.87 kJ/m 2 . On the other hand, impact strength decreased with adding MES in PLA/NR blends. The glass transition temperature and cold crystallization temperature decreased with adding both of NR and MES. Furthermore, adding both NR and MES influenced the degree of crystallinity and the crystal form of PLA. This finding might be explained considering the dispersion of NR and MES particles, inhibiting the movement of PLA molecular chain. In addition, PLA composites had rough surfaces with adding of NR and MES. Both NR and MES particles were embedded and uniformly dispersed in PLA continues matrix. © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Science and Technology of the Emerging Materials. Keywords: Poly(lactic acid) composites; natural rubber; modified eggshell powder * Corresponding author. Tel.: +6-644-233-073 extension 3351 E-mail address: somdee_patch@hotmail.com