A Consolidated Approach for Analytical Testing of Recycled Industrial Plastics

Significance of Topic

Polyamide recycling addresses critical needs in the automotive and plastics industries by reducing CO₂ emissions, conserving resources and supporting circular economy goals. High-performance polymers, such as Nylon-based materials, can replace heavier metal components, but consistent quality and safety must be maintained when reusing or reprocessing scrap materials.

Study Objectives and Overview

This case study evaluates a comprehensive analytical workflow to compare virgin and post-industrial recycled polyamide (PrestaMID™) pellets and molded worm gear parts. The goals are to characterize thermal, molecular, mechanical and chemical differences as a function of regrind content (0–100%), and to determine how recycled content affects component performance.

Methodology and Instrumentation

A multi‐technique approach was used:

• Thermogravimetric Analysis (TGA) to assess thermal degradation profiles.
• Differential Scanning Calorimetry (DSC) and Modulated DSC (MDSC) for melting/crystallization behavior and enthalpic relaxation.
• Size-Exclusion Chromatography (SEC/GPC) using HFIP mobile phase and ACQUITY APC XT columns to measure molecular weight distribution.
• Pyrolysis-Atmospheric Pressure GC-High Resolution MS (py-APGC-HRMS) with ToF detection and UNIFI™ software for chemical fingerprinting and multivariate marker identification.

Key Results and Discussion

TGA showed that gears and pellets with 100% recycled content decomposed at temperatures ~10–20 °C lower than virgin samples, indicating reduced thermal stability. DSC data revealed nearly identical melting points across all blends, while enthalpic recovery increased with regrind percentage, suggesting higher brittleness risk. SEC/GPC demonstrated a 24% drop in peak molecular weight (from 126 kDa to 97 kDa) and broader distribution for fully recycled gears. Py-APGC-HRMS combined with PCA and S-plot analyses identified unique pyrolyzate markers in recycled samples, such as N-vinylcaprolactam, aiding targeted chemical monitoring.

Benefits and Practical Applications

The consolidated analytical protocol enables manufacturers to:

• Quantify the impact of recycled content on thermal and mechanical properties.
• Detect chemical markers that differentiate virgin vs. recycled polymers.
• Optimize regrind proportions without compromising component safety.
• Support compliance strategies for future regulations on recycled plastic quotas.

Future Trends and Applications

Advances may include automated multivariate monitoring, expansion to other polymer families, integration with real-time process controls and development of harmonized standards. Emerging high-throughput calorimetric and chromatography platforms could streamline quality checks in closed-loop recycling.

Conclusion

This integrated analytical framework demonstrates that combining thermal analysis, advanced SEC, and soft-ionization HRMS provides a robust basis for assessing recycled polyamide performance. Such a strategy supports safe automotive applications and advances industrial recycling targets.

Reference

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