Brittle to ductile transition of polystyrene by high temperature programming

• Main Author: Tan, Alden Zheng Ching
• Other Authors: Huang Weimin
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/167494
• Institution: Nanyang Technological University

Polystyrene (PS) is one of the most used thermoplastics in the world due to its inexpensiveness, lightweight, and excellent mechanical properties. This project investigated polystyrene's brittle to ductile transition as a shape memory polymer in the form of Shrinky Dinks. The project aimed to explore the effects of programming temperature on this transition of mechanical property. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) tests were done to determine PS's glass transition temperature, setting up the programming temperatures for the project. With the help of a device that forces uniaxial shrinkage, the samples will be heated and allowed to shrink in the temperatures set. The heated samples are viewed under a polarizing lens to understand the internal stress during shrinkage. The results from the uniaxial tensile test done on programmed samples have shown some extent of brittle to ductile transition due to high temperature programming. Recommendations for future work were made, including improving the design of the testing device to minimize the curvature of the samples, using photoelasticity results as a reference for cutting samples to ensure consistency and modifying the programming process to heat the polymer evenly to the desired temperatures, to further study on this shift in mechanical property of PS and provide valuable insights into its potential applications in the field of engineering.