Determining the composition and microstructure of ethylene-propylene copolymers by pyrolysis-gas chromatography.
The average composition and detailed microstructure of copolymers of ethylene and propylene have been studied by pyrolysis-gas chromatography (Py-GC), using a statistical modeling approach to analyze the data. The trimer distribution obtained from Py-GC is used to infer monomer arrangement information, which is quantified in terms of a number-average sequence length for each monomer. These values are used to define the microstructure and to calculate the average composition. Compared with other available techniques, Py-GC provides a simple, quick and reliable approach to study the microstructure and composition of polyolefin copolymers. Details of this Py-GC method are discussed, including an examination of its advantages and disadvantages, and a summary of the qualitative and quantitative analysis aspects of this approach is presented. The combination of a statistical modeling approach with Py-GC to study copolymer composition and microstructure allows one to investigate the complex problem of monomer arrangement in copolymers using a widely available analytical technique. We expect that with further advances in separation technology, especially two-dimensional gas chromatography (GC x GC), research of this type will be become increasingly accurate and reproducible in the near future.
Wang
Frank Cheng-Yu
FC
Corporate Strategic Research, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801, USA. frank.c.wang@exxonmobil.com
Lohse
David J
DJ
Chapman
Bryan R
BR
Harrington
Bruce A
BA
D000475:Alkenes / Q000032:analysis / Q000737:chemistry*; D002849:Chromatography, Gas / Q000379:methods*; D005030:Ethylenes / Q000032:analysis / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000032:analysis / Q000737:chemistry*
D000475:Alkenes; D005030:Ethylenes; D011108:Polymers; C036216:ethylene; C013658:propylene