Dynamical mechanical and impact strength behavior of 3D‐printing testing specimens manufactured by fused filament fabrication of isotactic polypropylene/functionalized titania nanotubes nanocomposites: Influence of β‐crystal promoting

Abstract

AbstractThermomechanical and impact properties of isotactic polypropylene nanocomposites reinforced with titania nanotubes (TiNTs) at weight distributions of 0.5, 1, and 1.5 wt% were investigated. The goal of this study was to create a novel iPP‐based nanocomposite filament fused filament fabrication (FFF) with improved thermo‐mechanical and impact properties to enable the creation of more customized geometries. First, TiNTs were chemically functionalized with pimelic acid (PA) to promote the β‐crystalline phase using Ca as anchoring. FTIR results revealed the presence of new bands at 1575 and 1413 cm−1, which were attributed to the anchoring of the PA molecule on the TiNT surface. TEM images of the TiNTs confirmed its tubular morphology before and after the functionalization, while the SEM/EDS analysis showed the good dispersion of carbon which can only come from the organic molecule employed in the functionalization. The nano‐reinforcements were incorporated by extrusion generating a filament to produce 3D‐printed specimens. The efficacy of the modified reinforcement as a β‐crystalline phase promoter was evaluated by wide‐angle x‐ray diffraction. The nanocomposite with 1% modified TiNTs showed the highest β‐crystal promotion with a kβ‐index of 89% while the nanocomposites reinforced with unmodified TiNTs reached only 15%. Furthermore, the thermomechanical and impact properties were characterized by dynamic mechanical analysis and Izod. In the first, the storage modulus (E′) was higher than the raw iPP for all nanocomposites, with an increase of about 148% and 107%, while the nanocomposite with a high percentage of β‐crystal showed an increase of 183% in the impact strength properties. A shift of Tg to higher temperatures was attributed to better interfacial interactions polymer/nano‐reinforcement because of the functionalization. The modified nano‐reinforcement was able to generate a 3D‐printed nanocomposite with higher stiffness and impact strength properties than the raw iPP.