Investigation of the Properties of Polyetheretherketone Blends and Carbon-Filled Composites Based on them

The study of the properties of PEEK blends with different melt flow rate (MFR) and carbon-filled composites based on them was carried out. It was found that with an increase in the relative difference in the MFR of the blended PEEKs, there is an increase in the deviation of the experimental MFR values from the additive ones. Up to a relative difference in the MFR of the components equal to 60%, the blends obey the additivity rule. It is shown that the achievement of a certain MFR value by blending polymers with different viscosities leads to the production of materials with similar properties. Carbon-filled composites based on PEEK blends also demonstrate very similar rheological, mechanical and thermal properties, which indicates the effectiveness of the method of blending PEEKs with different viscosities to achieve the required rheological properties.

Antiplasticization of Polymer Materials: Structural Aspects and Effects on Mechanical and Diffusion-Controlled Properties

Antiplasticization of glassy polymers, arising from the addition of small amounts of plasticizer, was examined to highlight the developments that have taken place over the last few decades, aiming to fill gaps of knowledge in the large number of disjointed publications. The analysis includes the role of polymer/plasticizer molecular interactions and the conditions leading to the cross-over from antiplasticization to plasticization. This was based on molecular dynamics considerations of thermal transitions and related relaxation spectra, alongside the deviation of free volumes from the additivity rule. Useful insights were gained from an analysis of data on molecular glasses, including the implications of the glass fragility concept. The effects of molecular packing resulting from antiplasticization are also discussed in the context of physical ageing. These include considerations on the effects on mechanical properties and diffusion-controlled behaviour. Some peculiar features of antiplasticization regarding changes in Tg were probed and the effects of water were examined, both as a single component and in combination with other plasticizers to illustrate the role of intermolecular forces. The analysis has also brought to light the shortcomings of existing theories for disregarding the dual cross-over from antiplasticization to plasticization with respect to modulus variation with temperature and for not addressing failure related properties, such as yielding, crazing and fracture toughness.