K. Sheikh - Department of Mechanical Engineering, Najafabad branch, Islamic Azad University, Najafabad, Iran.
H. Shahrajabian - Department of Mechanical Engineering, Najafabad branch, Islamic Azad University, Najafabad, Iran.

The main purpose of this study is to prepare the nanocomposite samples with synergistic properties containing the mechanical, thermal and antibacterial properties. For this purpose, the combination of cellulose nanofiber (CNF) and Ag (silver) nanoparticles were incorporated into polylactic acid (PLA) matrix by solution casting method. The CNF in constant content of ۱ wt.% and Ag nanoparticles in the content of ۱, ۳, and ۵ wt.% were incorporated into the PLA matrix. The structure and morphology of the nanocomposite samples was characterized by FE-SEM, and mechanical, antibacterial, and thermal properties of the nanocomposites were evaluated by tensile, agar disk-diffusion, and DSC tests, respectively. FE-SEM images showed the uniform dispersion of the nanoparticles within the polymer matrix. The simultaneous addition of two nanoparticles significantly raised the mechanical properties such as tensile strength and tensile modulus by ۴۰% and ۹%, respectively. However, CNF had no considerable effect on the thermal and antibacterial properties of the PLA matrix. Unlike CNF, Ag nanoparticles significantly improved the antibacterial properties of the nanocomposites against staphylococcus aureus and Escherichia coli bacteria, and enhanced the thermal stability of the PLA matrix. Ag nanoparticles improved the degree of crystallinity of PLA from ۱۰.۵% to ۱۷.۹%, and Tm from ۱۴۷.۸ to ۱۵۳.۶ °C. By incorporating ۵wt.% Ag nanoparticles, the inhibition duameter increased from ۲۰ mm to ۳۹ mm for staphylococcus aureus.    

antibacterial properties, Cellulose Nano-fiber, poly lactic acid, Silver nanoparticles, thermal properties