Self‐lubricating polyamide 6 and polyamide 6.6 microcapsule‐based composites

• Published in: Journal of applied polymer science 2024-09, Vol.141 (35), p.n/a
• Main Authors: Grünewald, Moritz, Herbig, David, Heilig, Michael, Rudloff, Johannes, Bastian, Martin, Engelmann, Gunnar, Hirsekorn, Max, Latnikova, Alexandra
• Format: Article
• Language: English
• Subjects: Coefficient of friction; friction; functionalization of polymers; Injection molding; Injection molding machines; Lubricants; Lubrication; Mechanical drives; Mechanical properties; Mechanical tests; Particle size; Particulate composites; Polyamide resins; polyamides; Power transmission; Service life; Shell stability; Synthesis; synthesis and processing techniques; Thermal stability; thermoplastics; Tribology; wear and lubrication; Wear rate
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.55894

Polymeric applications with extended service life and low energy loss due to friction are of great interest in conveyor and power transmission technology. Self‐lubricating systems utilizing microcapsules hold significant potential for increasing energy efficiency and extending the operational life of these applications. This study focuses on synthesizing oil‐filled microcapsules through in situ polymerization of polyamide and their incorporation in polyamide 6 and polyamide 6.6. Microcapsules with a core made of thermally stable lubricant Food Lube, and particle diameter D90 of 50 μm were synthesized and isolated as a free‐flowing powder via spray‐drying procedure. The resulting powder demonstrated high thermal stability (loss of 5% at 350°C) due to the high thermal stability of both core and shell materials. A compounding process utilizing a twin‐screw extruder was developed to blend microcapsules into thermoplastic matrices. An injection molding machine forms tension rods. The composites' tribological properties are assessed through ball‐on‐disc tests conducted in both oscillation and rotation. The friction coefficient and wear rate of the composites experience a reduction of 79% and 56% for polyamide 6, as well as 77% and 75% for polyamide 6.6. Mechanical testing of the microcapsule composites reveals a decrease in mechanical properties. Schematic illustration of the synthesis of lubricant‐filled microcapsules, optical microscopy of the capsules and tribological properties in a rotational ball on disc test using capsule‐filled polyamide 6 and a 100Cr6 steel counter‐body.