The effects of temperature and moisture on flexural and thermomechanical properties of neat and filled epoxy with both multiwall carbon nanotubes (CNT), carbon nanofibers (CNF), and their hybrid components were investigated. Two regimes of environmental aging were applied: Water absorption at 70 °C until equilibrium moisture content and thermal heating at 70 °C for the same time period. Three-point bending and dynamic mechanical tests were carried out for all samples before and after conditioning. The property prediction model (PPM) was successfully applied for the prediction of the modulus of elasticity in bending of manufactured specimens subjected to both water absorption and thermal aging. It was experimentally confirmed that, due to addition of carbon nanofillers to the epoxy resin, the sorption, flexural, and thermomechanical characteristics were slightly improved compared to the neat system. Considering experimental and theoretical results, most of the epoxy composites filled with hybrid carbon nanofiller revealed the lowest effect of temperature and moisture on material properties, along with the lowest sorption characteristics.

The present study focuses on the mechanical and viscoelastic characterization of 3D-printed PLA, fabricated in three different printing orientations (0°, 45°, and 90°) and four different nozzle temperatures (210, 220, 230, and 240 °C). By employing a combination of static and dynamic mechanical analysis (DMA) testing, as well as differential scanning calorimetry (DSC) analysis, this work aims to investigate the relationship between processing parameters and the resulting properties of PLA. DSC results showed that higher nozzle temperatures enhance the degree of crystallinity, which in turn affects the mechanical and viscoelastic behavior of PLA. Regardless of the nozzle temperature, the flexural strength decreased as the printing orientation degrees increased. However, it was found that the higher the nozzle temperature, the higher the flexural strength for the same orientation, and the smaller the strength deviations per specimen. DMA results indicated that as the printing orientation increased, glass transition temperature (T_g) values increased while storage modulus values decreased. At the same time, in both cases, by increasing nozzle temperature, an increase in T_g and a respective increase in storage modulus values is observed due to the increase in the degree of crystallinity.