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Using spectroscopy with chemometrics to measure polymer molar mass
Author(s) -
Shenton Martyn J,
Herman Henryk,
Stevens Gary C
Publication year - 2000
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/1097-0126(200009)49:9<1007::aid-pi511>3.0.co;2-h
Subject(s) - molar mass , chemometrics , polymer , materials science , analytical chemistry (journal) , viscometer , chromatography , process engineering , chemistry , viscosity , composite material , engineering
The ability to determine the molar mass of a polymer is of fundamental importance to describe polymer molecular characteristics. Conventional methods for measuring molar mass include viscometry, osmometry, light scattering and analytical gel permeation chromatography (GPC). Although high quality data can be obtained by these methods, the results can be significantly affected by sample preparation, and they are often time consuming and unsuitable for real‐time on‐line processing. In this paper, we demonstrate the potential of determining polymer molar mass using optical spectroscopy combined with chemometric analysis. This is technically attractive because optical spectroscopy is routinely used to collect process data on‐line and some refineries routinely monitor and control blending using near‐infrared (NIR) spectroscopy. A comparable development to monitor polymer molar masses on‐line from systems already being used to measure density and melt index, would be of potential value to many sectors of the polymer production and processing industry. Chemometrics is a multivariate methodology that allows the information from entire spectra to be used; it can be considered as a maximal compression technique. Extracted ‘factors’ can then be regressed against property data by using a well‐characterized set of ‘training’ samples to produce predictive regression models. We will show that simple spectroscopic methods, such as the Raman technique discussed in this paper, when coupled with chemometrics, are capable of providing molar mass and distribution information. We will illustrate this with reference to poly(dimethylsiloxane)s (PDMSs) in the liquid phase. © 2000 Society of Chemical Industry