Detection and Mapping of Chimassorb 944FD Antioxidant Additive in Polyethylene Using TOF-SIMS

Area of Science:

• Materials Science
• Analytical Chemistry
• Polymer Science

Background:

• Assessing additive homogeneity in polymers is crucial for material performance.
• Traditional methods for mapping antioxidant distribution in polyethylene have limitations.
• Chimassorb 944FD (C944) is a common antioxidant in linear low-density polyethylene (LLDPE).

Purpose of the Study:

• To evaluate Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) for quantifying C944 homogeneity in LLDPE.
• To identify suitable mass fragments for accurate C944 distribution analysis.
• To compare the efficacy of gallium versus indium primary beams.

Main Methods:

• TOF-SIMS analysis using gallium and indium primary beams.
• Investigation of parent ion (m/z 599) and fragment ion (m/z 58) signals for C944.
• Development of a calibration curve for quantitative analysis.

Main Results:

• The parent ion (m/z 599) was too weak for mapping C944 at typical concentrations (0.1-0.5%).
• A mass fragment at m/z 58 proved to be a reliable surrogate for mapping C944 distribution.
• Accurate imaging was achieved down to 0.1% C944 concentration, with a linear calibration curve.
• Indium primary beams enhanced quantitative accuracy and reduced polyethylene background interference.

Conclusions:

• TOF-SIMS, using a fragment ion at m/z 58 and an indium primary beam, is a viable method for assessing C944 homogeneity in LLDPE.
• This approach enables accurate quantitative analysis of antioxidant distribution at low concentrations.
• The findings offer improved analytical capabilities for polymer additive characterization.