A new method for studying the degradation of polymers at high temperatures

Bin Zhao, Isaac Kantorovich, Ezra Bar-Ziv

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations

Abstract

A new method for the investigation of the degradation of charring and noncharring polymers has been developed. In this method, the degradation is studied in an electrodynamic chamber where a single polymer particle can be levitated at a fixed position until reaction completion. The particle is heated by a focused laser beam to reach the desired temperature, the particle's surroundings can be controlled and strong gas flows can be imposed on the particle. The high heating rate (104-105 K/s) and small size of the particle (50-200 μm) prevent mass and heat-transfer limitations, inevitable in other methods. The method enables one to measure various forces significant for a small particle, such as free- and forced-convection and photophoretic forces, which are sensitive to the temperature, the thermal and optical properties of the particle, and the surrounding gas. Valuable information on these properties can be gained on-line with the rate of mass loss measurements. The method has been used for investigation of the degradation of polystyrene particles, both in oxidizing and nonoxidizing environments. The character of degradation depends on temperature. A double mass decay transient was observed at high temperatures (above 550 °C), while only one characteristic time was observed for lower temperatures, for pyrolysis. Similar results were observed for oxidation, but at lower temperatures. The first decay corresponds to pyrolysis of the melted polystyrene to produce char, while the second process corresponds to a slow reaction within the porous char. The observed shrinkage of the char particle is indicative of the transformation of the microporous structure of char during chemical reaction. From the photophoretic force measurements, it has been found that during the fast decay stage, the optical properties were changed significantly.

Original languageEnglish
Pages (from-to)2865-2871
Number of pages7
JournalSymposium (International) on Combustion
Volume27
Issue number2
DOIs
StatePublished - 1 Jan 1998
Event27th International Symposium on Combustion - Boulder, CO, United States
Duration: 2 Aug 19987 Aug 1998

ASJC Scopus subject areas

  • Chemical Engineering (all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Mechanical Engineering
  • Physical and Theoretical Chemistry
  • Fluid Flow and Transfer Processes

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