Raman spectroscopy as a non-destructive tool to quantify the comonomer content in ethylene/1-olefin copolymers

Abstract

Ethylene/1-olefin copolymers, ranging from 1-butene to 1-octadecene, have been studied with Raman spectroscopy and the spectral changes upon comonomer incorporation have been analyzed. The Raman spectra of ethylene/1-olefin copolymers are characterized by a band ensemble in the lower frequency region below 1000 cm-1 which is a characteristic scattering from the comonomer segments. The spectra show bands due to scattering from the polyethylene sequences which also reflect the effect of the morphological changes occurring with the increasing comonomer content. By correlating the bands characteristic of the comonomer to those of the ethylene sequences, an internal intensity standard was identified. This also caters to the effect of the experimental parameters such as sample focus and spectral acquisition time for calibration of the comonomer content. This approach was also extended to amorphous ethylene/norbornene copolymers and a similar method for quantification was developed. The major advantages of this method are the minimum amount of sample preparation, and the low sample size, enabling even micrograms of the sample to be measured. Due to these, quantification with Raman spectroscopy is uniquely suited for online quality control and liquid chromatography which require a fast and robust analytical methodology

Monitoring crosslinking inhomogeneities in ethylene vinyl acetate photovoltaic encapsulants using Raman microscopy

“…The short spectral acquisition times and minimal sample preparation make it a predestined technique for online quality control and in situ reaction monitoring. 15,16 The coupling of a light microscope to the Raman instrument allows spatially high resolved proling of morphological or chemical variations, which includes: blend compositions, functionalization of micro-polymer particles in colloids, identication of unknown materials in art works and quality control in pharmaceuticals. 15,[17][18][19][20][21] The high spatial resolution and the depth of information retrieved has been widely applied for the analysis of confectioned polymer products, such as in multi layered lms or bers, where, due to the length scale, locating and identifying individual components is oen impossible using other imaging techniques like infrared microscopy.…”

Determination of Short Chain Branching in LLDPE by Rheology

“…The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/macp.202200150 DOI: 10.1002/macp.202200150 have also been applied to SCB quantification. [18] Chemical composition distribution (CCD) can be obtained using fractionation techniques based on crystallization such as temperature rising elution fractionation (TREF), [19][20][21][22] crystallization analysis fractionation (CRYSTAF), [23][24][25] and crystallization elution fractionation (CEF) [23,26] developed by Wild, Monrabal, and Soares, respectively. Among emerging techniques for characterizing comonomer distribution, Cong and Macko have developed fractionation techniques based on interaction with a graphical column: thermal gradient interaction chromatography (TGIC) and solvent gradient interaction chromatography.…”