Analysis of Ethylene Vinylacetate (EVA) Copolymer by Double-shot Pyrolyzer PY-2020D

Significance of the topic

Pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) offers a fast, sensitive route to characterize polymer composition, detect residual monomers and additives, and study thermal decomposition. For materials like ethylene-vinyl acetate (EVA) copolymer, understanding volatile components and degradation profiles is critical in quality control, recycling, and product performance.

Objectives and Study Overview

This study demonstrates an analytical workflow combining Shimadzu GC/MS with a Frontier Laboratories PY-2020D double-shot pyrolyzer. The goals are to:

• Identify and quantify residual vinyl acetate monomer and oligomers in EVA
• Compare single-shot and double-shot pyrolysis modes
• Resolve thermal desorption products and polymer pyrolysis fragments in a single analysis

Methodology and Instrumentation

The analysis employed three modes available on the PY-2020D:

• Single-shot (flash pyrolysis)
• Double-shot (thermal desorption followed by flash pyrolysis)
• Evolved gas analysis (EGA-direct MS)

The EGA scan heated EVA from 50 °C to 650 °C at 20 °C/min. GC conditions included an Ultra ALLOY+5 column (30 m×0.25 mm I.D., 0.25 µm), initial 50 °C (5 min), ramp 10 °C/min to 320 °C (30 min), split injection (1:50), and helium carrier at 100 kPa. MS was operated in EI mode (m/z 10–500, 0.5 s scan interval) with interface at 280 °C.

Instrumentation used

• Pyrolyzer: Frontier Laboratories PY-2020D double-shot pyrolyzer
• Gas chromatograph-mass spectrometer: Shimadzu GC/MS system
• Column: Ultra ALLOY+5 (30 m×0.25 mm I.D., 0.25 µm)

Main Results and Discussion

EGA revealed small peaks at 100–260 °C, attributed to desorption of residual monomer (vinyl acetate) and additives (m/z 60 for CH3COOH and m/z 57 fragment). Larger decomposition peaks appear at 260–550 °C, reflecting polyvinyl acetate backbone cleavage.

Double-shot pyrolysis split the sample analysis:

1. First step at 400 °C (thermal desorption) identified oligomeric vinyl acetate fragments (C15–C18 carbonyl species).
2. Second step at 550 °C (flash pyrolysis) yielded hydrocarbon fragments up to C27, indicative of deeper backbone breakdown.

This two-stage approach provided complementary data: volatile residuals and additive profiles from the first shot, and structural polymer fragments from the second.

Practical Implications and Benefits

• Rapid, solvent-free detection of trace monomers and additives
• Comprehensive thermal decomposition profiling in one sample run
• Enhanced sensitivity to both volatile and heavy polymer fragments
• Improved QC workflow for EVA-based products and recycling feedstocks

Future Trends and Potential Applications

Advances may include coupling double-shot pyrolysis with high-resolution MS or infrared detectors, automated sample introduction for high throughput, and integration with polymer recycling streams to monitor degradation. Further applications could target biodegradable plastics, composite materials, and environmental microplastic analysis.

Conclusion

The combined GC/MS and PY-2020D double-shot pyrolysis system enables detailed, efficient analysis of EVA copolymers. By separating thermal desorption and flash pyrolysis, this method provides robust data on residual monomers, additives, and polymer backbone fragments. It supports quality control and materials research with minimal sample preparation and high analytical sensitivity.