Identification of Branches in Low-Density Polyethylenes by Fourier Transform Infrared Spectroscopy

Abstract

ABSTRACT:Qualitative and quantitative analysis of short chain branches was carried out on a series oflow-density polyethylenes by Fourier transform infrared spectroscopy. The peak position of the methyl symmetrical deformation bands around 1378 em -1 was found to vary with the type of branches and used for identification of the branch type in low-density polyethylenes. The reciprocals of extinction coefficients of the methyl deformation bands were determined for various branch types on the basis of 13 C NMR data. The values changed from 0.39 to 0.76 depending on the type of branch. The methyl rocking bands ranging from 880 to 940 em -1 were examined using brominated samples. The peak positions also depended on the type of branch. For the methylene rocking bands, the peak at 772.2 em -1 due to the ethyl branch was clearly observed, but that due to the n-butyl branch was not detected around 745 em -1 , indicating the n-butyl absorption to be located very close to 730cm-1 rather than 745cm-1

Characterization and microstructure study of low‐density polyethylene by Fourier transform infrared spectroscopy and temperature rising elution fractionation

“…They were determined by NMR studies of some commercial LDPEs. 4 According to these values, in LDPE (grade LF0200), butyl short branches per 100 carbon atoms must be This is in good agreement with the method introduced here.…”

“…In LDPE, however, SCBD is more complex because short-chain branches (SCB) are produced by intramolecular chain transfer or backbiting of the growing radical, 3 whereas in LLDPE, SCB are introduced into the backbone by the copolymerization of ethylene with a-olefins; this makes it possible to introduce certain select types of SCB into LLDPE. 4 A variety of techniques have been used to measure SCB and their distribution in LDPE, such as infrared (IR) spectroscopy, 5-8 1 H-and 13 C-NMR spectroscopy, 9,10 pyrolysis hydrogenation/gas chromatography, 11,12 and g-radiolysis. 13 Among these methods, only spectroscopic methods have provide direct measurements of SCB, and IR spectroscopy has attracted more attention because of its simplicity, speed, and low equipment cost.…”

Flow instability for binary blends of linear polyethylene and long-chain branched polyethylene

“…In the table, information on short-chain branches is also provided. The number of short-chain branched was measured by Fourier-transfer Infra-red spectroscopy using the method proposed by Usami and Takayama [50]. Moreover, the apparent flow activation energy is evaluated by the rheological shift factors at various temperatures.…”

“…Since it is generally accepted that a high viscous polymer melt slips on the wall, the slippage can be the origin of surface instability [35,43,44]. Gross melt fracture is attributed to the flow instability at a die entrance, and associated with long time relaxation mechanism [38,[45][46][47][48][49][50][51]. Yamaguchi et al found that gross melt fracture of LDPE can be avoided by applying intense shear history, which weakens the relaxation mechanism associated with long-chain branches, by shear modification [51].…”

Effects of intensive microbial metabolism on starch-filled polyethylene films in controlled compositing windows.

“…Films of the extracted polymers were cast at 130°C by applying a 12 bar pressure for 72 s and then analyzed by a Perkin-Elmer 1600 FT-IR spectrophotometer. The number of vinyl and vinylidene end-groups per 1,000 carbon atoms was evaluated according to the procedure reported by Usami and Takayama (29).…”