| NSF Org: |
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems |
| Recipient: |
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| Initial Amendment Date: | November 22, 2013 |
| Latest Amendment Date: | November 22, 2013 |
| Award Number: | 1347196 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Harsha Chelliah
hchellia@nsf.gov (703)292-7281 CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems ENG Directorate for Engineering |
| Start Date: | April 1, 2014 |
| End Date: | March 31, 2019 (Estimated) |
| Total Intended Award Amount: | $412,418.00 |
| Total Awarded Amount to Date: | $412,418.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3112 LEE BUILDING COLLEGE PARK MD US 20742-5100 (301)405-6269 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
MD US 20742-5141 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | CFS-Combustion & Fire Systems |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
Abstract
This proposal describes a five-year project focused on developing a quantitative understanding of burning for charring and intumescing polymeric systems. These systems represent one of the most promising and environmentally benign solutions to the hazards associated with polymer flammability. The mechanism of their flame resistance has not been well understood, hampering material development efforts. The PI proposes to design a set of controlled radiative pyrolysis experiments combined with a high-resolution X-ray tomography, thermogravimetric analysis and differential scanning calorimetry. This combination of experimental techniques is expected to yield accurate data on the kinetics and thermodynamics of the thermal degradation, char morphology evolution, and heat flow inside this class of materials. The experimental results will be interpreted using a numerical model concurrently developed. This model is capable of simulating transient conductive, radiative and convective heat transfer, mass transport, and multiple chemical reactions in a three-dimensional, non-homogeneous object of non-static dimensions.
This project will produce an in-depth understanding of char growth dynamics in a wide range of polymeric systems including a new generation of biodegradable materials. This understanding is expected to transform the field of flame resistant material design and enable qualitative improvements in public safety. The research results will be rapidly disseminated among scientists and practicing engineers and utilized to strengthen an array of partnerships that the PI has established with industry and professional organizations. These results will also form a foundation of the PI?s educational initiatives. The PI will develop an interactive material flammability demonstration for secondary school students. This demonstration will be used to foster the student?s interest in science while promoting fire safety. The PI will combat a low graduation rate among racial minority college undergraduates by engaging them in the fire safety research. The PI will also develop the first of its kind graduate course on material flammability.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Project Outcomes:
1. Developed a systematic methodology for the measurement of kinetics and thermodynamics of the thermal decomposition of charring polymers and composites based on thermogravimetric analysis and differential scanning calorimetry. Demonstrated this methodology on a broad range of polymeric solids. Further expanded this methodology to include the Microscale Combustion Calorimetry into the analysis process to determine the heats of combustion of gaseous decomposition products.
2. Designed radiative pyrolysis experiments featuring simultaneous temperature and mass monitoring of coupon-sized material samples. The first prototype of the Controlled Atmosphere Pyrolysis Apparatus (CAPA) was developed and tested on non-charring and charring polymers. Good results were obtained for non-charring polymers. However, significant uncertainties in the sample boundary conditions were observed for charring and intumescent materials. The second version of the Controlled Atmosphere Pyrolysis Apparatus (CAPA II) was developed to address the deficiencies of the first prototype. The boundary conditions in the CAPA II were thoroughly quantified and its performance was successfully demonstrated using several charring and intumescent materials.
3. Developed a capability to quantitatively assess geometry of the cellular structure of developing chars. A method for quantifying evolution of the overall sample geometry during pyrolysis has been developed and demonstrated on several materials. The cellular char structure was probed by applying advanced image analysis to high resolution sample cross section photographs. The method provided reliable information on char pore size distribution and porosity for pore sizes larger than 100 micron.
4. Developed a numerical model, ThermaKin2Ds, capable of simulating transient conductive, radiative and convective heat transfer, mass transport, and multiple chemical reactions in a non-homogeneous pyrolyzing object of non-static dimensions. The model was successfully applied to the analysis of zero-dimensional (thermally thin), one-dimensional and two-dimensional pyrolysis problems. This model was further expanded to enable simulation of two-dimensional axisymmetric sample geometries, which are consistent with the conditions implemented in the CAPA II. This expanded model has been verified using analytical solutions of transient heat and mass transport problems.
5. Applied these newly developed experimental tools and modeling to charring polymeric solids to elucidate in-depth understanding of the dynamics of their pyrolysis process. A wide range of charring systems, including biodegradable materials, was successfully analyzed to obtain full sets of properties that define pyrolysis. These property sets were carefully validated by comparing the mass loss or burning rate histories measured in the CAPA II experiments to the model predictions. A general quantitative relation between the char pore structure descriptors and its thermal transport parameters has been identified.
6. Disseminated the results of this research by giving presentations at scientific and professional conferences. The results of this project were presented at the 2016 BCC Flame Conference, Interflam 2016, 2016 ACS Fall National Meeting, 2016 FAA Fire and Cabin Safety Conference, 2016 International Confederation for Thermal Analysis and Calorimetry Meeting, 2017 US National Combustion Meeting, 2017 International Symposium on Fire Safety Science, 2017 European Meeting on Fire Retardant Polymeric Materials, 2018 BCC Flame Conference and 2018 International Symposium on Combustion.
7. Developed a graduate course on material flammability (ENFP 629M) partially based on the results of this project. This course was taught for the first time during the fall of 2015 to the mechanical engineering students majoring in fire science. This course is now taught on bi-annual basis; it has become a permanent part of the graduate fire protection engineering curriculum.
8. Supervised development of a one semester class entitled “Engineering Math and Physics through Fire Dynamics” for high school students. This class was designed to expose the students to the fundamental concepts in mathematics, physics and chemistry needed to understand and solve engineering problems encountered in the field of fire dynamics. This class was taught during the fall of 2015 semester and again in the spring and fall of 2016 and 2017. Over 40 high school students completed this class. This class is now a permanent outreach activity of the Fire Protection Engineering Department.
9. The material analysis methodology developed in this project is already being used in a number of flame-retardant material development projects conducted in collaboration with the industry. This methodology is expected to lead to development of new, environmentally friendly fire-safe materials.
Last Modified: 03/27/2019
Modified by: Stanislav Stoliarov
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