Using a Benchtop X-Ray Diffractometer for Phase Determination of Polymers

The preceding hundred years have witnessed a major societal shift: the age of plastics has taken over from the age of metals, initiating an enormous demand on polymers as a result. Consequently, fast and appropriate analytical methodologies are needed to evaluate the broad array of various polymer compounds, the physical characteristics of which are fundamentally dependent on the structure and nature of the polymers.

Utilizing X-ray diffraction (XRD) enables the convenient determination of the crystallographic structure, in addition to the category of polymer materials.

Instrument

The Thermo Scientific™ ARL™ EQUINOX 100 X-ray diffractometer engages a bespoke Cu (50 W) or Co (15 W) micro-focus tube supported by mirror optics. This low wattage system negates the requirement for an external water chiller or other exterior infrastructure, and permits the apparatus to be comfortably conveyed from the laboratory to the field, or between laboratories.

The ARL EQUINOX 100 offers extremely quick data gathering rates in comparison to other available diffractometers. This is due to its distinctive curved position sensitive detector (CPS), which quantifies all diffraction peaks simultaneously, and in real time. Consequently, it is completely appropriate for both reflection and transmission computations (c.f. Figure 1).

ARL EQUINOX 100 X-ray diffractometer.

Figure 1: ARL EQUINOX 100 X-ray diffractometer.

For XRD calculations, sheet samples of PE (Polyethylene) and PP (Polypropylene) were calculated in transmission geometry for five minutes under Cu-Kα radiation. The quality of the data acquired with benchtop ARL EQUINOX 100 is similar to data deriving from standard high-power floor standing apparatus. Qualitative analysis was undertaken with the assistance of MDI JADE 2010, alongside the ICDD PDF4+ Organic database.

Results

Correlating the data to ICDD PDF4+ Organic database explicitly generates high density Polyethylene (HD PE) and Isotactic Polypropylene as outcomes. (c.f. Figure 2).

Diffraction patterns of HD PE (top; 5 min measurement time) and α-PP (bottom; 5 min measurement time).

Figure 2: Diffraction patterns of HD PE (top; 5 min measurement time) and α-PP (bottom; 5 min measurement time).

Conclusion

The ARL EQUINOX 100 benchtop instrument, in collaboration with the MDI JADE 2010 software suite and ICDD pdf4+ Organic database, is an efficient screening solution, which can easily ascertain the structure and type of polymer materials within limited time parameters.

Authors: Dr. Simon Welzmiller, Ju Weicai, XRD Application Specialists

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific - Elemental Analyzers.

For more information on this source, please visit Thermo Fisher Scientific - Elemental Analyzers.

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