The crystallinity of chemically bonded PA‐PTFE‐oil compounds by X‐ray diffraction and DSC

• Published in: Journal of polymer science (2020) Vol. 61; no. 16; pp. 1828 - 1842
• Main Authors: Nguyen, Thanh Duong, Farshchi, Negin, Ulbricht, Tim Johannes Thomas, Leopold, Anne‐Katrin, Schmidt, Thomas, Uhlig, Kai, Stommel, Markus, Voit, Brigitte, Gedan‐Smolka, Michaela
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15.08.2023
• Subjects: chemically bonded polyamide‐polytetrafluoroethylene‐oil; crystallization; hardness; mechanical properties
• ISSN: 2642-4150; 2642-4169
• DOI: 10.1002/pol.20230035

One of the major shortcomings of compounding polyamide (PA), polytetrafluoroethylene (PTFE), and olefinic oils is the fact that they are incompatible. To overcome this issue, using energy radiation in the presence of oxygen leads to the breakage of the PTFE chain to generate hydrophilic functional groups (COF, COOH) and peroxy radicals. The created functional groups and radicals can be used to induce a chemical bond between PA and PTFE as well as between PTFE and olefinic oil molecules. In addition, the hardness of compounds significantly influences the application of materials as solid‐lubricant. It is well known that crystallinity affects the hardness of materials. In the presented study, the effects of the chemical bonding PA‐PTFE/PA‐PTFE‐oil on the crystallization behavior of various types of PA in chemically bonded PA‐PTFE‐oil‐chemically bonded compounds, which were prepared by reactive two‐step extrusion, were investigated via DSC and X‐ray diffraction. The crystallite size of PA46 and PA66 in PA‐PTFE‐chemically bonded (cb) compounds was significantly increased compared with pure PA. At the same time, the d‐spacings of the PA segment in PA‐PTFE compounds were significantly narrower. Due to the chemical coupling, the compounds showed a slight change in hardness compared with pure PA.