The goal of this research is to obtain quantitative information on chemical speciation over time during high temperature material thermal decomposition. The long term goal of the research will be to impact structural fire safety by developing a data base of characteristic “burn signatures” for combustible structural materials.

The comparison was made based on the thermal profile and chemical species generated by heating the PMMA with high intensity IR lamps.

Data aquisition (DAQ) system:

  • temperature data was gathered at various points using multiple thermocouples attached to a thermocouple input board
  • concentrations of the gas species CO, CO2 & O2 and total hydrocarbons (THC) were gathered by a combustion gas analyzer (CGA)
  • both the temperature and chemical equipment were read and logged in real time
In order to establish procedure and to generate data for benchmark materials, the first material tested in these preliminary tests is poly-methyl-methacrylate (PMMA). Material samples are heated in an infrared (IR) heating chamber until they undergo pyrolysis. The sample is heated with radial symmetry to ensure transport events are minimized.
Time resolved quantitative measurements of the exhaust species CO, CO2, O2 and hydrocarbons (HC) are obtained using a combustion gas analyzer. A temperature profile is obtained using several K-type thermocouples in various locations in and around the furnace. Data from both the combustion gas analyzer and thermocouple input device is logged in real time using software developed in LabVIEW.
 
During heating, the PMMA sample undergoes two distinct processes. First, pre-combustion pyrolysis is characterized by the appearance a peak in the THC signal between 600-650 °C. Secondly, at about 900 °C flaming combustion occurs as evidenced by an exothermic reaction reported by the thermocouples. The time sequence of the production of HC, O2 depletion and CO2 production are consistent with combustion in an excess-oxidizer environment.
 

 
To probe further:

  • [pdf] C. A. Kramer, R. Loloee, I. S. Wichman and R. N Ghosh, "Time-resolved measurements of pyrolysis products from thermoplastic poly-methyl-methacrylate (PMMA), Proc. ASME 2009 Int. Mech. Eng. Congress & Exposition, paper: IMECE2009-11256, p. 99-105 (2009).


Acknowledgements

Thanks to our collaborators in this project:

  • Prof. Indrek Wichman, Dept. of Mechanical Engineering, Michigan State University


Funding:
  • Strategic Partnership Grant - Michigan State University