Tribological properties of Poly(lactide acid) composites
K.Bula 1*, D.Wośkowiak1, P.Brzęk1, Z. Sydow2, Ł. Wojciechowski2
1Institute of Materials Technology, Poznan University of Technology, Poznan, Poland
2Institute of Machines and Motor Vehicles, Poznan University of Technology,Poznan, Poland
*Corresponding author karol.bula@put.poznan.pl
Nowadays, materials selection for bearings made of polymeric materials is focused on application of organic reinforcements into polymeric matrices due to presence of residual fatty acids that can substantially reduce coefficient of friction [1-3]. In the presented work the agricultural wastes like cherry shells and plum shells were combined with two types of poly(lactide acid) PLA and the composites has been tested in terms of tribological properties without additional lubrication. Shells were pulverized to a powder state and then subjected to separation into different grade fractions: 200-400 µm; 400-630 µm; 630 - 800 µm. Composites with 15% by weight of cherry/plum powders and two grades of crystalline PLA 2500 HP and 3100 HP were melt mixed via co-rotating twin screw extruder. Samples for tribological test were injection molded. Tribological tests were carried out with the application of the “block-on-ring” system, where the metallic ring (1045 steel) was used as a counter-surface (Fig. 1a). The kinetic friction test conditions were as follows: ring speed 150 rpm, top load 250N, test duration 30 min. The frictional behaviour was analysed on the basis of the measured values for the friction torque and the CoF (coefficient of friction). The most signifficant reduction in the value of CoF was noted for PLA 3110 HP/15% of plum shell (powdered to 400-630 um particle range) compared to neat PLA and it was over 40% (from 0,37 to 0,22 kinetic CoF) (Fig. 1b,c). The research was financially supported by the PUT, internal subsidy 0613/SIGR/2403.
Keywords: block-on-ring test, adhesive wear, poly(lactide acid), agricultural wastes
References
[1] Ibrahim, M. A.; Hirayama, T.; Khalafallah, D.; An investigation into the tribological properties of wood flour reinforced polypropylene composites. Materials Res. Expr. 2020, 7 (1), 015313. DOI: 10.1088/2053-1591/ab600c
[2] Sydow, Z.; Sydow, M.; Wojciechowski, Ł.; Bieńczak, K.; Tribological performance of composites reinforced with the agricultural, industrial and post-consumer wastes: A review. Materials 2021, 14(8), 1863. DOI: 10.3390/ma14081863
[3] Wojciechowski, Ł.; Sydow, Z.; Bula, K.; Gapiński, B.; Friction and wear of polypropylene-based composites reinforced with cherry seed powder. Tribology Int. 2023, 179, 108177. DOI:10.1016/j.triboint.2022.108177