A polymer visualization system with accurate heating and cooling control and high-speed imaging.
A visualization system to observe crystal and bubble formation in polymers under high temperature and pressure has been developed. Using this system, polymer can be subjected to a programmable thermal treatment to simulate the process in high pressure differential scanning calorimetry (HPDSC). With a high-temperature/high-pressure view-cell unit, this system enables in situ observation of crystal formation in semi-crystalline polymers to complement thermal analyses with HPDSC. The high-speed recording capability of the camera not only allows detailed recording of crystal formation, it also enables in situ capture of plastic foaming processes with a high temporal resolution. To demonstrate the system's capability, crystal formation and foaming processes of polypropylene/carbon dioxide systems were examined. It was observed that crystals nucleated and grew into spherulites, and they grew at faster rates as temperature decreased. This observation agrees with the crystallinity measurement obtained with the HPDSC. Cell nucleation first occurred at crystals' boundaries due to CO₂ exclusion from crystal growth fronts. Subsequently, cells were nucleated around the existing ones due to tensile stresses generated in the constrained amorphous regions between networks of crystals.
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada. awong@mie.utoronto.ca.
Anson
A
Wong
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada. nqzhou@scut.edu.cn.|National Engineering Research Center of Novel Equipment for Polymer Processing, the Key Laboratory of Polymer Processing Engineering, Ministry of Education of China, South China University of Technology, Guangzhou 510641, China. nqzhou@scut.edu.cn.
Yanting
Y
Guo
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada. park@mie.utoronto.ca.|National Engineering Research Center of Novel Equipment for Polymer Processing, the Key Laboratory of Polymer Processing Engineering, Ministry of Education of China, South China University of Technology, Guangzhou 510641, China. park@mie.utoronto.ca.
Chul B
CB
Park
National Engineering Research Center of Novel Equipment for Polymer Processing, the Key Laboratory of Polymer Processing Engineering, Ministry of Education of China, South China University of Technology, Guangzhou 510641, China. nqzhou@scut.edu.cn.
Nan Q
NQ
Zhou
D002152:Calorimetry, Differential Scanning / Q000295:instrumentation / Q000379:methods; D011108:Polymers / Q000737:chemistry*; D013816:Thermodynamics
D011108:Polymers