A Consolidated Approach for Analytical Testing of Recycled Industrial Plastics

Importance of the Topic

Lightweight high performance polymers offer climate benefits in transport. Recycling post industrial polyamide parts can reduce greenhouse gas emissions. Ensuring quality and safety of recycled components is essential for adoption in safety critical automotive systems.

Objectives and Overview of the Study

This case study aims to establish an integrated analytical workflow for evaluating structural thermal molecular and chemical differences between virgin and recycled polyamide gears and pellets. It focuses on assessing the influence of regrind proportion on material performance for steering gear worm wheels.

Methodology

The approach compares virgin and varying regrind content 0 to 100 percent polyamide samples through multiple analytical platforms. It examines melting and decomposition behavior crystallinity molecular weight distribution and chemical fingerprint profiles.

Instrumentation

• Thermogravimetric analyzer for thermal stability and decomposition studies
• Differential scanning calorimeter with modulated DSC capability for glass transition and enthalpic recovery analysis
• Advanced polymer chromatography system using HFIP mobile phase and ACQUITY APC XT columns for molecular weight distribution
• Pyrolyzer coupled to APGC soft ionization and Xevo G2 XS QTof high resolution time of flight mass spectrometer
• Statistical software tools including PCA and S plot within UNIFI for multivariate analysis

Main Results and Discussion

TGA revealed reduced thermal stability of fully recycled pellets and gears with maximum mass loss at lower temperatures by 10 to 20 C. DSC confirmed similar melting points and crystallinity across samples while enthalpic recovery increased with regrind content indicating potential embrittlement. MDSC separated glass transition and quantified relaxation energy correlating with recycled fraction. APC GPC demonstrated a 24 percent reduction in peak molecular weight for gears with 100 percent regrind versus virgin material alongside shifts in Mw Mn and PDI. APC XT columns yielded faster analysis and lower solvent consumption relative to traditional GPC. Pyrolysis soft ionization HRMS combined with multivariate analysis distinguished sample groups and tentatively identified unique markers such as N vinylcaprolactam in recycled gears.

Benefits and Practical Applications

• Provides a comprehensive assessment ensuring performance and safety of recycled components in automotive gear systems
• Supports determination of maximum recycling cycles additive needs and material optimization
• Reduces analysis time and solvent use via advanced GPC and soft ionization MS
• Enables chemical marker identification for quality control regulatory compliance and traceability

Future Trends and Utilization Possibilities

Emerging analytical methods will enhance understanding of polymer degradation mechanisms additive interactions and structure property relationships. Integration with evolving recycled content regulations will guide material design strategies. Further structured experiments will refine correlations between processing history mechanical performance and long term durability. Advances in high resolution mass spectrometry and data analytics will expand capabilities for compound identification in complex polymer matrices.

Conclusion

This consolidated analytical approach combining thermal analysis APC GPC and pyrolysis soft ionization high resolution MS offers a robust toolkit for characterizing recycled polyamide materials. It enables data driven selection of regrind proportions while safeguarding material performance in safety critical automotive applications.

References

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