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The origins of volatile oxidation products in the thermal degradation of polypropylene, identified by selective isotopic labeling

Polymer Degradation and Stability

Bernstein, Robert; Thornberg, Steve M.; Assink, Roger A.; Irwin, Adriane N.; Hochrein, James M.; Brown, Jason R.; Wiemann, Dora K.

Making use of polypropylene samples that are selectively labeled with carbon-13 at each of the three unique positions within the repeating unit, we are conducting mass spectral analyses of the volatile organic oxidation products that are produced when the polymer is subjected to elevated temperature in the presence of air. By examination of both the parent and fragmentation ion peaks in the mass spectrum, we are able to identify the positioning of the C-13 labels within the volatile compounds, and thereby map each compound onto its site of origin from within the macromolecular structure of polypropylene. Most of the organic oxidation products are remarkably specific in terms of their genesis from the polymer. The structural results are discussed in terms of the oxidation chemistry of the macromolecule.

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TYPE Journal Article YEAR 2007
DOIOSTIScopus

Preliminary Investigation of the Thermal Decomposition of Ablefoam and EF-AR20 Foam (Ablefoam Replacement)

Ulibarri, Tamara A.; Erickson, Kenneth L.; Wiemann, Dora K.; Castaeda, Jaime N.; Borek, Theodore T.; Renlund, Anita M.; Miller, Jill C.

Preliminary thermal decomposition experiments with Ablefoam and EF-AR20 foam (Ablefoam replacement) were done to determine the important chemical and associated physical phenomena that should be investigated to develop the foam decomposition chemistry sub-models that are required in numerical simulations of the fire-induced response of foam-filled engineered systems for nuclear safety applications. Although the two epoxy foams are physically and chemically similar, the thermal decomposition of each foam involves different chemical mechanisms, and the associated physical behavior of the foams, particularly ''foaming'' and ''liquefaction,'' have significant implications for modeling. A simplified decomposition chemistry sub-model is suggested that, subject to certain caveats, may be appropriate for ''scoping-type'' calculations.

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TYPE Report YEAR 2001
DOIOSTI

Final report for the designed synthesis of controlled degradative materials LDRD

Loy, Douglas A.; Ulibarri, Tamara A.; Curro, John G.; Wiemann, Dora K.; Guess, Tommy R.

The main goal of this research was to develop degradable systems either by developing weaklink-containing polymers or identifying commercial polymeric systems which are easily degraded. In both cases, the degradation method involves environmentally friendly chemistries. The weaklinks are easily degradable fragments which are introduced either randomly or regularly in the polymer backbone or as crosslinking sites to make high molecular weight systems via branching. The authors targeted three general application areas: (1) non-lethal deterrents, (2) removable encapsulants, and (3) readily recyclable/environmentally friendly polymers for structural and thin film applications.

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TYPE Report YEAR 2000
DOIOSTI

Proton beam targets shot on PBFA-II

Review of Scientific Instruments

Wiemann, Dora K.

In recent proton beam experiments on PBFA-II, foam-filled gold targets and gas-filled spherical exploding pushers were shot as physics targets. Surrounding these targets were gold foils used to characterize the beam. The target fabrication and characterization are presented in this paper.

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TYPE Conference YEAR 1992
OSTIScopus
Results 26–48 of 48
Results 26–48 of 48
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