RESUMO
Endowing a single material with various types of luminescence, that is, exhibiting a simultaneous optical response to different stimuli, is vital in various fields. A photoluminescence (PL)- and mechanoluminescence (ML)-based multifunctional sensing platform is built by combining heterojunctioned ZnS/CaZnOS:Mn2+ mechano-photonic materials using a 3D-printing technique and fiber spinning. ML-active particles are embedded in micrometer-sized cellulose fibers for flexible optical devices capable of emitting light driven by mechanical force. Individually modified 3D-printed hard units that exhibit intense ML in response to mechanical deformation, such as impact and friction, are also fabricated. Importantly, they also allow low-pressure sensing up to ≈100 bar, a range previously inaccessible by any other optical sensing technique. Moreover, the developed optical manometer based on the PL of the materials demonstrates a superior high-pressure sensitivity of ≈6.20 nm GPa-1 . Using this sensing platform, four modes of temperature detection can be achieved: excitation-band spectral shifts, emission-band spectral shifts, bandwidth broadening, and lifetime shortening. This work supports the possibility of mass production of ML-active mechanical and optoelectronic parts integrated with scientific and industrial tools and apparatus.
RESUMO
The aim of this article is to study the influence of some printing parameters and postprocessing on mechanical properties of polylactic acid samples manufactured by fused deposition modeling with a 3D printer. The effects of different building orientations, concentric infill, and postprocessing by annealing were analyzed. In this sense, uniaxial tensile and three-point bending tests were performed to determine the ultimate strength, modulus of elasticity, and elongation at break. Among all printing parameters of interest, the print orientation can be considered one of the most important, being fundamental in the mechanical behavior. Once samples were fabricated, annealing processes were also considered, close to the T g, in order to study the effects on mechanical properties. In the modified print orientation, the average values for the E and the σ TS are 3337.15-3337.92 and 36.42-37.62 MPa, compared with default printing with the E and the σ TS that are 2541.63-2692.34 and 28.81-28.89 MPa, respectively. In the annealed samples, the values for the Ef and the σf are 2337.73 and 63.96 MPa, compared with the reference samples with the Ef and the σf values of 2164.40 and 59.66 MPa, respectively. Hence, the print orientation and postprocessing must be taken into account as important factors for the final properties of the desired product.
