Anti-flammable polymers and nanocomposites Conte Center for Polymer Research Univ. of Massachusetts Amherst Todd Emrick, Polymer Science & Engineering, UMass Amherst Funding: Federal Aviation Administration, U.S. Army, and the members of the polymer flammability industrial consortium (Cluster F) at the University of Massachusetts Amherst
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Anti-flammable polymers and nanocomposites polymers and nanocomposites Conte Center for Polymer Research Univ. of Massachusetts Amherst Todd Emrick, Polymer Science & Engineering,
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Anti-flammable polymers and nanocomposites
Conte Center for Polymer Research Univ. of Massachusetts Amherst
(not pictured: P.K. Sudeep, Irem Kosif, Jimmy Lawrence, Emily Pentzer)
Halogenated flame-retardants (FRs) - Highly effective for flame-retardation as additives to polymer materials
- Face legislative scrutiny, due to health and environmental concerns(particularly related to bioaccumulation and toxicity)
Synthetic organic polymers- A mainstay of modern society, used in fabricating textiles, upholstery, construction materials, vehicles, and electronic devices
- Pose a significant threat due to their inherent flammability
Background
Small molecule flame-retardants
OBrn Brn
n=1-5Brn Brn
Br
Br
Br
HO
Br
OH
Halogenated
Non-halogenated
Aluminum trihydrate
Magnesium hydroxide
Phosphorus, nitrogen, and silicon-based inorganics
Effective and inexpensiveUsed in commodity polymers(polycarbonate, polyurethanes,epoxy ,etc.)
Environmental persistenceToxicity Restrictions and legislation
Environmentally-friendlyUsed in commodity polymers
High loading needed for FR activityNegative impact on mechanical properties of
host polymer materialsLimitation in high-temperature applications
Broader Project Objectives
Synthesis of novel inherently fire-resistant polymers
Requirements:• High thermal stability• Low combustion heat release rate• Minimal toxic fume release• Environmental friendly (non-halogenated)• High char formation
Polymers with high C/H ratio (aromatic, high degree of unsaturation) show better fire-resistant properties, as the lack of hydrogen fuel leads to facile char formation
Presentation topics for:The Sixth Triennial International Fire & Cabin Safety Research Conference
Walters, R.N.; Lyon, R.E. J. Appl. Polym. Sci. 2003, 87, 548Pyrolysis combustion flow calorimetry (PCFC) enables effective analysis of milligram quantitiesof novel and known materials!
Bisphenol A Polycarbonate(Lexan)
Bisphenol C Polycarbonate
O
O
O
n n
ClCl
O O
OHO
ClCl
OH
Bisphenol C
Bisphenol A vs. Bisphenol C
J. Polym. Sci. Part A: Polym. Chem. Ed. 1980, 18, 579; J. Appl. Polym. Sci. 2003, 87, 548
Rationale for observed bis-phenol C charring
Ramirez, M. L. Thermal Decomposition Mechanism of 2,2-Bis(4-hydroxyphenyl)-1,1-dichloroethylene Based Polymers. DOT/FAA/AR-00/42.; Department of Transportation, Federal Aviation Administration, National Technical Information Service: Springfield, VA, 2001; Stoliorav, S.I.; Westmoreland, P.R. Polymer 2003, 44, 5469; van der Waals et al. J. Mol. Cat. A 1998, 134, 179
Presence of chlorine assists in setting up the rearrangement chemistry
Conversion into diphenylacetylene – key step in char formation
Deoxybenzoin conversion to diphenylacetylene at high temperatures
R RR R
R
O
RR R
R R
300-500 oC
BPC
Deoxybenzoin
-H2O
Δ
ΔSilica-alumina catalyst
R
Cl Cl
R-Cl2
Δ
Char
BHDB preparation from desoxyanisoin, and integration into polyarylates
• One step synthesis of monomer in high yields, up to 500 g scale
Small-scale flame test Conducted by placing a sample specimen approximately (2×0.5×0.025) cm in a propane torch flame at a 45 deg angle for 5-10 s and noting the time required for the sample to self-extinguish upon removal from the flame
a) 3-BPT polymer film formed by hot-pressing; b) 3-BPT fibers pulled from the melt.
Small-scale flame test configuration; b) samples after the test (left: 3-BPT polyarylate; right: Kapton®.
Films of BPT polymers were seen tobe extinguish immediately.(‘self-extinguishing’)