THE IMPACT OF MINERAL FILLERS ON THE TRIBOLOGICAL PROPERTIES OF POLYMER COMPOSITES

Abstract

Correctly selected and modified minerals have a significant positive effect on the strength and tribological characteristics of composite polymer materials. In this regard, the influence of mineral filler modification and the size of their particles on the tribological properties of the composites based on two polymer matrices: a copolymer of formaldehyde with dioxolane and polyphenylene sulfide is studied. It is found that samples with activated filler have lower values ​​of the friction coefficient and wear compared to non-activated filler. Activation contributed to an increase in the hardness of the composite material due to an increase in the newly formed surface of the filler before casting the samples and reduction in the grain size.

The tribological properties of polymer composites were influenced to a greater extent by the size of the filler grains compared to mechanical activation. It is found that the smaller the grain size of the mineral filler, the lower the friction coefficient and wear of the composite. At developing composites based on formaldehyde copolymer and mineral fillers of travertine or bentonite, their wear resistance increased by 3,7…5 times, and the friction coefficient decreased by 1.4...1.6 times, which was achieved due to the strength and rigidity characteristics of the fillers used in relation to the more plastic and soft antifriction matrix. At choosing a harder and more heat-resistant polyphenylene sulfide matrix, the effect of using minerals increased significantly when using molybdenum concentrate as a filler: wear resistance increased by 1.8 times, and the friction coefficient decreased by 2 times. Regardless of the choice of the matrix, optimal tribological characteristics were obtained using nanosized fractions of fillers, which is due to the maximum specific surface energy of the particles, ensuring reliable adhesion of the filler to the polymer matrix.

It has also been established that the use of calcium carbonate-rich marble powder in the compositions of asbestos-free brake friction composites provides a high and stable friction coefficient due to the absorption of additional heat by the marble powder.