Sensitivity index and strain rate dependent metrics of lightweight acrylonitrile styrene acrylate (ASA) in MEX additive manufacturing

The properties of acrylonitrile styrene acrylate (ASA) are similar to acrylonitrile butadiene styrene. However, it is more robust against environmental phenomena. Therefore, it is capable of use in outdoor applications. Its behavior under different strain rates in 3D printing is still insufficiently investigated. The aim herein was to report the 3D printed ASA parts' mechanical performance for test speeds varying from 10 to 300mm/sec. The mechanical performance is affected by the viscoelastic behavior of the material and the 3D printing structure. ASA was sourced in raw form. It was then extruded into filament and finally into tensile specimens. Thermal examinations included thermogravimetric analysis and differential scanning calorimetry. Scanning electron microscopy on the lateral and fractured surfaces contributed to the samples’ morphological evaluation. The ultimate strength, yield strength, stiffness, and toughness were assessed from the performed tensile experiments. To investigate the material’s deformation mechanisms, the strain rate sensitivity index m was determined. The samples subjected to higher strain rates had higher strength (∼47MPa, compared to 41MPa at the standard test speed, ∼13% increase), stiffness (∼510MPa, compared to ∼470MPa at the standard test speed, ∼8% increase), and toughness (∼7.42MJ/m 3 at 250mm/min, compared to ∼4.67MJ/m 3 at 75mm/min, ∼37% increase). Toughness was higher at low and high strain rates and lower at median values. Ductility increased at higher strain rates, contributing to the toughness increase. The strain rate sensitivity index was higher at low speeds (∼0.06 at 75mm/min, compared to ∼0.018 at 250mm/min). Samples were more brittle at medium strain rates. These findings provide valuable information for the design of ASA 3D printed components operating under high-speed loads. • Acrylonitrile styrene acrylate (ASA) is suitable for outdoor applications in MEX 3D printing. • ASA response under various strain rates (10 to 300 mm/min elongation speeds). • Strain hardening effect is reported with increase in strength and stiffness at higher test speeds. • Higher strain rate sensitivity values are reported at lower test speeds. • Toughness and brittleness decrease at median test speeds.