Structural and Thermo-mechanical Evaluation of Two Engineering Thermoplastic Polymers in Contact with Ethanol Fuel from Sugarcane

Special polymers have been used in the manufacture of storage structures and pipelines avoiding corrosive processes during ethanol fuel transport/storage. Therefore, this work investigated comparatively the effects of the ethanol on the physical-mechanical properties of poly (ether ether ketone) (PEEK) and polyamide 11 (PA-11) based on ageing tests. The WAXD and DSC results demonstrated slight reductions on the crystallinity degree of the aged PEEK, contrariwise to what happened with PA-11, where X_cincreased after ageing. However, the results of thermal, thermomechanical and mechanical analysis (TGA, DMTA, tensile and micro-IITs) demonstrated that PEEK is stable and no significant changes were observed in its elastic modulus (E_y≈ 3.4 GPa, E’ andE_it≈ 3.7 GPa) or glass transition temperature. PA-11, conversely, was sensitive to ethanol fuel and expressive changes of its physical-mechanical properties were verified. For both materials, a reasonable correlation between crystallinity and mechanical properties was established.

Keywords:
Ageing; Ethanol; Microindentation tests; Microhardness; Elastic modulus; Crystallinity