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Polybenzimidazole (PBI) is the most sought polymer for high thermal stability, mechanical strength and retention at elevated temperatures. However, its potential for tribological applications, especially at high temperatures and under various wear modes, is not yet explored in depth. In this work, commercially available PBI was investigated under sliding wear against steel at elevated temperatures and different pressures. A relation between the linear wear rate and the test temperature could be shown. But the wear mechanisms do not differ very much within the temperature range tested. In addition, the solid particle erosion resistance of PBI under different impact angles and surface finishes was investigated at ambient and high temperature. A higher erosion rate took place when the temperature was increased. Overall, PBI showed a semi-brittle erosive failure ( α at 45°) behaviour. Scanning electron microscopy was used to understand the wear mechanisms in more detail, and white light profilometry allowed to get information about the topography of the fresh and eroded surfaces. [ABSTRACT FROM AUTHOR]

Both polylactide (PLA) and poly(butylene adipate- co-terephthalate) (PBAT) are biodegradable polymers. They are thermoplastics which can be processed using conventional polymer processing methods. In this study, microfibrillar-reinforced composites (MFC) based on PLA/PBAT (PLA/Ecoflex) blends in different weight ratios were prepared under industry-relevant conditions by melt extrusion followed by continuous cold drawing of the extrudates. Strip-like specimens (films) and plates (laminates) of the drawn blends were prepared by compression molding (CM) at processing temperature above the melting temperature ( T) of PBAT, but below T of PLA. SEM and WAXS observations show that the extruded blend components are isotropic, but become highly oriented after drawing, and they are converted into MFC-structured polymer-polymer composites after CM. An effect of PLA microfibrils on the non-isothermal crystallization of the Ecoflex during cooling from the melt, associated with the formation of crystalline regions of the matrix around the fibrils, was observed. Depending on the blend composition, the compression-molded samples possess a 3- to 7-time higher tensile strength as well as a 15-30 higher modulus than the neat Ecoflex. In addition, the MFC-structured plates exhibited superior barrier properties compared to the neat Ecoflex, e.g., the oxygen permeability decreased by up to 5 times. [ABSTRACT FROM AUTHOR]

Up to now, poly- para-phenylene (PPP) can be considered as the stiffest and strongest polymer under ambient temperature conditions. As an amorphous thermoplastic, a thermal treatment will not change the material's morphology, but may influence its inner free volume (physical aging) and corresponding mechanical properties. This was investigated in this study with regard to the hardness and fracture toughness of PPP. It turned out that under the thermal conditions chosen, only moderate effects on these properties could be detected. Besides it was of interest how PPP compares in these properties relative to other advanced thermoplastics (neat and short glass fiber reinforced). Various features, such as striations and parabolic holes, on the fracture surfaces of PPP were also discussed. [ABSTRACT FROM AUTHOR]

Studies thermal stability of frictional surface layer and wear debris of epoxy nanocomposites in relation to the mechanism of tribological performance improvement. Preparation of the composite materials; Frictional coefficients of epoxy and its composites.

Reports on polypropylene composites filled with in-situ grafting polymerization modified nano-silica particles. Uniqueness of the properties of materials resulting from the nanoscale microstructure; Improvement of the mechanical properties of the composites; Challenge of the homogeneous dispersion of nanoparticles in polymers due to the tendency to agglomerate during melt blending.