How to Conduct Thermogravimetric Analysis on Recycled Polymers

To perform a TGA test on post-consumer polymers, begin by obtaining a small, representative sample of the material. Use pure, dehydrated reprocessed plastic bits, ideally reduced to uniform granules to promote even thermal distribution. Measure approximately 3–12 mg of the sample using a microbalance with 0.01 mg accuracy and load into a non-reactive vessel made of ceramic or platinum, depending on the maximum operating temperature of your analysis.

Place the crucible into the thermogravimetric analyzer and secure the lid to avoid external interference or volatilization. Link the analyzer with a inert gas atmosphere, typically high-purity N₂ or Ar, to suppress oxidative reactions that prevents oxidation during heating. If you are interested in oxidative degradation behavior, you may switch to air or oxygen at a post-inert phase, but begin under inert conditions for control measurements.

Program the analyzer to heat the sample at a steady ramp rate, usually between min, from ambient conditions up to 750–900°C. The heating rate affects the precision of degradation events, so reduced ramps enhance peak separation but extend test duration. Record mass change of the sample throughout the entire thermal cycle.

As the polymer undergoes pyrolysis, the analyzer will generate a real-time graph of relative mass vs. kelvin. The baseline region represents the moisture-free material, followed by distinct inflections corresponding to the chain scission processes, stabilizers, pigments, flame retardants, or foreign residues. Recycled polymers often contain unreacted precursors, softeners, or curing agents that break down across varied thermal thresholds, so multi-stage degradation profiles are typical.

After the run ends, examine the weight-loss profile to locate critical thermal transitions, such as the T_onset, T_max, and remaining solids. Contrast against those of virgin polymer or reference samples to quantify material deterioration, contamination, or copolymer composition. A elevated char content may indicate the addition of calcium carbonate, glass fibers, تولید کننده گرانول بازیافتی or talc, while accelerated mass loss suggests previous thermal exposure or hydrolytic breakdown.

Conduct a baseline run with an reference vessel under the same conditions to account for any background weight changes. Perform minimum of three replicates to validate consistency. Document the sample source, recycling history, and any pretreatment steps, as these factors profoundly affect outcomes. This method delivers a robust technique to determine thermal behavior and constituent content of reclaimed plastics, helping to guide reprocessing methods and ensure product consistency in reprocessing.