Thermo Scientific Antaris Site Map

The Thermo Scientific Antaris™ line of Fourier Transform Near-Infrared (FT-NIR) analyzers is well-suited to analyze a variety of polymers commonly found in chemical or industrial applications. FT-NIR doesn’t require complicated sample preparation like other spectroscopic techniques and can be used to quickly and easily identify or quantify polymer precursors, raw materials, or finished product. In addition to chemical properties such as side chain type, FT-NIR is used to identify and quantify physical properties such as density or pellet size as well as extent of polymerization. Furthermore, FT-NIR is useful for tracking the kinetics (reaction rate) of the polymerization process, and can be used to monitor polymer viscosity to ensure proper flow characteristics.

Polymerization Kinetics—FT-NIR has been shown to effectively track the extent of reaction and reaction rate of different adhesive polymers. Two-component adhesive polymers consist of a monomer material and curing agent. When the two are mixed, the curing agent catalyzes the polymerization process. Chemical moieties present in the monomer are diminished while new chemical structures are formed during this process (figure 1). This change in chemical nature of the material can be quantified using NIR.

Polyethylene Identification—FT-NIR can be used to classify polyethylene as either high density or low density. This classification is valuable for ensuring proper feedstocks are used for manufacturing especially in cases where the materials are very close chemically. Furthermore, this type of polymer classification can aid in proper separation of recyclable materials. In addition to qualitative classification, FT-NIR can be used to quantitatively determine the densities of individual polymer samples.

Design of Experiment

Instrument: Antaris II Method Development Sampling (MDS) FT-NIR analyzer with integrating sphere module

Technique: Polymerizing material placed on integrating sphere then covered with reflecting foil

Rationale: Speed and extent of reaction are important parameters in chemical polymerization applications. This is a case where simple peak height measurements in NIR can be used to determine these fairly complex properties. Accurate measurement of polymerization is useful for chemical processing and is a valuable part of Process Analytics.

Samples: A polymerization application tracked the rate of reaction of three different two-component resins and adhesives. Each material was mixed and analyzed over a period of time using baseline corrected heights of selected identifying peaks. One sample was an epoxy resin shown to slowly react over 55 hours as indicated by the gradual loss of peaks associated with the epoxy functional group. A second polymer was an acrylate-based adhesive that was monitored over 20 hours during which the alkene functional groups disappeared during the setting process. A final rapid setting cyanoacrylate-based adhesive was similarly monitored for loss of alkene groups as the polymerization process was catalyzed by moisture in the air.