Examples of Heterogeneous Polymers Investigated by IR and Raman Microscopy

EXAMPLES OF HETEROGENEOUS POLYMERS INVESTIGATED BY IR AND RAMAN MICROSCOPY 

1 FTIR transmission images compared with SEM images 

The first example will deal with polymer blends consisting of polyamide (PA) and poly(tetrafluoroethylene) (PTFE). These polymer types are frequently used 

The first sample is a reactive poly(tetrafluoroethylene)/polyamide 6 (PTFE/ PA) blend [43]. When mixing PTFE micro-powder and PA in an extruder at about 280°C, relatively large PTFE particles occur in the final product because of immiscibility. By irradiation with electrons in air reactive groups in the PTFE powder are formed. These functionalised particles react with the molten PA in the extruder, and graft copolymers are formed, improving the compatibility of the components. At the same time a decrease in PTFE particle size proportional to the irradiation dose can be observed, and a PTFE/PA compound with better properties is produced. 

The second example, a blend sample consists of 80% PA 6.6, 18% PTFE and 2% silicone oil. From the relative concentrations, it can be seen that PA forms the matrix and provides the necessary stability to the bearing. PTFE acts as an incorporated lubricant. The two main components are not chemically linked. Therefore, silicone oil has been added to work as a boundary lubricant during the break-in phase of the bearing. Due to its liquid nature, it quickly migrates to the surface when pressure is applied and prevents abrasion at the first stage. Shortly after, a thin film of PTFE forms at the interface between the thermoplastic bearing and the counter part. 

---