Uniaxial hot tensile testing is widely used to characterise materials for thermoforming applications. Despite their broad applicability, conventional testing approaches often have limitations, including sample slippage and restricted experimental flexibility. This study presents a custom-built open heating system integrating ceramic infrared (IR) heaters designed to be coupled to a tensile testing machine. This approach offers a cost-effective method for conducting hot tensile testing, achieving a cost reduction of approximately 90% compared to commercially available environmental chambers. Temperature calibrations validated IR thermography as the temperature monitoring process and established repeatable heating profiles up to 215 °C within a 20 mm gauge region of three materials: high-impact polystyrene (HIPS), polycarbonate (PC), and amorphous polyethylene-terephthalate (A-PET). The system performance was validated through two case studies. For HIPS, the system successfully confined deformation to the gauge area and exhibited reproducible deformation behaviour, achieving a maximum linear draw ratio (LDR) of 6.1. In the second case study, the electromechanical integrity of screen-printed carbon tracks (Micromax™ ME201) onto PC was assessed. The electrical resistance increased exponentially with local strain (R 2 = 0.96), with an increase by a factor of 6.9 in relative resistance at a LDR of 2.3. This was consistent with strain-driven microcrack propagation without ink delamination. Although constraints remain regarding thermal gradients and manual synchronisation, the developed system provides a practical and modular approach for reproducible localised hot tensile testing of thin thermoformable films and printed functional materials.
Ribeiro et al. (Mon,) studied this question.