Rongjuan Cong
Dow Chemical Company
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Publication
Featured researches published by Rongjuan Cong.
Journal of Separation Science | 2013
Rajesh Chitta; Tibor Macko; Robert Brüll; Matthew Miller; Rongjuan Cong; Willem deGroot
The elution behavior of polyethylene (PE) and the three stereoisomers of polypropylene (PP) was studied on porous graphite along with three other carbon-based sorbents, carbon-clad zirconia particles, activated carbon, and exfoliated graphite in a systematic way in this work. Decahydronaphthalene, 1,2,3,4-tetrahydronaphthalene, 1,3,5-trimethylbenzene, tetrachloroethylene, xylene and p-xylene were used as mobile phases. While PE is adsorbed to various extents on all the tested carbonaceous sorbents from the majority of the solvents, PP is fully adsorbed only in selected cases. Testing alcohols (C7-C9) as mobile phase with Hypercarb™ indicates that all stereoisomers of PP are selectively adsorbed and desorbed when a solvent gradient alcohol→1,2,4-trichlorobenzene is used at 160°C. The retention of all stereoisomers of PP increases with the polarity of the alcohol. Linear PE is retained on Hypercarb™ even from 1,2-dichloro- and 1,2,4-trichlorobenzene, when a temperature below 120°C is applied, while it is not retained from these solvents at higher temperatures. All stereoisomeric forms of PP are not adsorbed under the same conditions. Some of the tested new sorbent/solvent systems have potential to be applied in routine analysis of industrially synthesised polyolefins.
Journal of Separation Science | 2010
Shayne Green; Snow Bai; Mike Cheatham; Rongjuan Cong; Wallace W. Yau
Antioxidants are added to polyolefins to improve the stability of the resin from oxidation and degradation during processing of the finished article and to increase product lifetime. Without antioxidants, polyolefins would quickly degrade during and after the extrusion or thermoforming process, which would cause inferior appearance and physical properties. The proper level must be added to protect the polymer and to minimize cost. Antioxidants are usually extracted from the resin and the extract is analyzed by RPLC, GC, or Fourier transform infrared spectroscopy. Unfortunately, many of these procedures require significant manual labor, time, and solvent, rendering them impractical for high-throughput work processes. In addition, they may not provide complete extraction of the additives depending upon the type of resin. A validated analytical method was needed for the determination of three common antioxidants, Irganox(®) 1010, Irganox(®) 1076, and Irgafos(®) 168 in polyolefin resins. This paper shows the determination of these antioxidants using dissolution followed by precipitation with o-xylene and methanol. Direct analysis of the solution is achieved in 8 min using RPLC.
Analytical and Bioanalytical Chemistry | 2011
Wallace W. Yau; Rongjuan Cong; David T. Gillespie
AbstractThis paper describes an analytical three-capillary viscometer detector that eliminates the traditional viscometer “hold-up” volume (commonly found in four-capillary designs) while maintaining cancellation of short-term pump noise and long-term baseline drift of temperature and solvent flow rate that are inherent in chromatography systems. This improvement allows a staggered sample injection approach in chromatography, yielding a significant increase in sample throughput by cutting down the chromatographic run time. It also provides a more robust design as it does not require capillary rebalancing, complex purging, flushing or changing the hold-up volume to accommodate long-term chromatographic use. Example of a four-capillary viscometer in a quad-detector GPC system.
Macromolecules | 2011
Rongjuan Cong; Willem deGroot; Al Parrott; Wallace W. Yau; Lonnie G. Hazlitt; Ray Brown; Matthew Miller; Zhe Zhou
Archive | 2010
Theresa J. Hermel-Davidock; Mehmet Demirors; Sarah M. Hayne; Rongjuan Cong
Macromolecular Symposia | 2012
Benjamin Monrabal; Nuria Mayo; Rongjuan Cong
Macromolecules | 2009
Zhe Zhou; James C. Stevens; Jerzy Klosin; Rainer Kümmerle; Xiaohua Qiu; David Redwine; Rongjuan Cong; Angela Taha; Jeff Mason; Bill Winniford; Paul Chauvel; Nikki Montañez
Archive | 2009
William Winniford; Rongjuan Cong; Theodore M. Stokich; Randy Pell; Matthew Miller; Abhishek Roy; Freddy Van Damme; Alexander Degroot; John W. Lyons; David M. Meunier
Archive | 2012
Teresa P. Karjala; Rongjuan Cong; Colleen Tice; Sarah M. Hayne; Mehmet Demirors; Lori L. Kardos
Macromolecular Symposia | 2012
Rongjuan Cong; A. Willem deGroot; Al Parrott; Wallace W. Yau; Lonnie G. Hazlitt; Ray Brown; Michael Cheatham; Matthew Miller; Zhe Zhou