Frequency Dependence of Glass Transition Temperature of Thermoplastics in DMA Analysis

The aim of this study is to investigate the effect of oscillatory loading frequency on the dynamic-mechanical properties of 3D printed thermoplastics, namely acrylonitrile-butadiene-styrene (ABS), glycol-modified polyethylene terephthalate (PETG), and polylactide, also known as polylactic acid (PLA). The investigated samples were manufactured using fused filament fabrication (FFF) technology and tested at different oscillation frequencies (1, 5, 10, 15 and 20 Hz). Dynamic mechanical analysis (DMA) demonstrated that an increase in the oscillation frequency causes an increase in the glass transition temperature (Tg) for all analyzed materials, while in the case of the used loading frequencies above 5 Hz, an almost linear dependence between the magnitude of the applied frequency and Tg was observed. The findings also show that with increasing frequency of mechanical loading, there are changes in the visco-elastic properties of the investigated polymers, specifically in the value of the storage modulus (E′), loss modulus (E′′) and loss angle (tan δ), which points to the complex behavior of the materials under dynamic conditions. The results of this study provide valuable insights for the use of 3D printed polymer materials in applications where they are exposed to dynamic stress - in the automotive or aerospace industries.