An open hardware 3-D printed device for measuring tensile properties of thermoplastic filament polymers at cryogenic temperatures.

With the emerging recognition of open scientific hardware, rapid prototyping technology such as three-dimensional (3-D) printing is becoming widely available for fields such as cryobiology, and cryopreservation, where material selection for instruments and hardware has traditionally been problematic due to extreme low temperatures. A better understanding of the mechanical properties of 3-D printing thermoplastics at cryogenic temperatures is essential to material selection, part design, and printing optimization. The goal of the present study was to explore the feasibility of development for a 3-D printed device ('CryoTensileDevice') to hold a test specimen in liquid nitrogen and be mounted in standard mechanical testing systems to evaluate 3-D printing material behaviors at cryogenic temperatures. The CryoTensileDevice was prototyped with flexible filaments with a per-unit material cost of < US$5 and a printing time of < 5 h. The commonly used printing filament polylactic acid (PLA) was selected to evaluate the utility of the CryoTensileDevice. At room temperature, the CryoTensileDevice did not significantly ( > 0.05) affect PLA tensile measurements such as Young's modulus, yield stress, yield strain, stress at break, or strain at break. With the CryoTensileDevice, specimens 3-D printed with PLA at 50%, 75%, and 100% infill rates had comparable tensile properties when tested at room and liquid nitrogen temperatures. The PLA showed superior performance in tensile properties in comparison to acrylonitrile butadiene styrene (ABS). This device can assist characterization of 3-D printing approaches for cryogenic work, and opens a pathway for future innovations to create a variety of 3-D printed devices to study a wide range of material properties for cryogenic applications.