Engineering topics

Burke, Luke A.

Publications and source records attributed to Burke, Luke A..

3 records

NASA NTRS1992

The effects of molecular structure on the electrical conductivity of polymers

The role of Quantum Theoretical Methods is both predictive and supportive of experimental results in Chemistry. Present day methods are able to calculate vibrational spectra and stereochemical interactions for molecules of moderate size (up to 20 atoms). As for the predictive side, the electronic structure of molecules and polymers can be calculated in order to narrow down the field of many potential candidates, which would have the novel properties looked for. The following has been accomplished at the Rutgers Camden Chemistry Department as results of calculations on molecular and polymeric systems of interest to the Polymers Branch of the NASA Lewis Research Center, under Grant NAG3-956.

Burke, Luke A.↗

NASA NTRS1992

Lower temperature curing thermoset polyimides utilizing a substituted norbornene endcap

Methoxycarbonyl bridgehead substituted nadic diacid monomethyl ester, when used as an endcapping monomer, lowered the cure temperature of thermoset PMR polyimides without seriously affecting other desirable properties, such as glass transition temperature and thermal oxidative stability. The C-13 CP/MAS NMR of model compounds was used to follow the cure of resin systems using both the unmodified nadic endcap and the methoxycarbonyl-substituted endcap. Rheological analysis and differential scanning calorimetry DSC also provided evidence for the lower curing nature of the substituted endcap. Two regioisomers of the bridgehead-substituted endcap were isolated, and their chemical structures were elucidated by X-ray crystallography. The model compound and molecular modeling studies conducted ruled out the possibility of regioisomeric imide formation in the substituted endcaps.

Waters, John F.↗

NASA NTRS1987

A quantum theoretical study of polyimides

One of the most important contributions of theoretical chemistry is the correct prediction of properties of materials before any costly experimental work begins. This is especially true in the field of electrically conducting polymers. Development of the Valence Effective Hamiltonian (VEH) technique for the calculation of the band structure of polymers was initiated. The necessary VEH potentials were developed for the sulfur and oxygen atoms within the particular molecular environments and the explanation explored for the success of this approximate method in predicting the optical properties of conducting polymers.

Burke, Luke A.↗