How to Conduct Thermogravimetric Analysis on Recycled Polymers

To conduct a TGA on post-consumer polymers, begin by preparing a small, representative sample of the material. Use untainted, moisture-free polymer pieces, ideally reduced to uniform granules to promote even thermal distribution. Determine approximately 5 to 10 milligrams of the sample using a ultra-sensitive weighing instrument and transfer into a sterile, low-mass container made of quartz or palladium, depending on the maximum operating temperature of your analysis.

Insert the container into the TGA instrument and secure the lid to prevent contamination or loss of material. Connect the instrument to a precisely regulated gas flow, typically nitrogen or argon, to suppress oxidative reactions that halts thermal degradation from air exposure. If you are interested in oxidative degradation behavior, you may transition to oxidizing gas at a subsequent phase, but start with an inert gas for baseline data.

Program the analyzer to heat the sample at a constant rate, usually between min, from ambient conditions up to 850°C. The thermal gradient affects the clarity of thermal transitions, so slower rates provide more detailed information but take longer. Track mass reduction of the sample throughout the entire thermal cycle.

As the polymer undergoes pyrolysis, the analyzer will record a continuous plot of mass loss against thermal exposure. The pre-decomposition phase represents the dry sample, followed by sudden declines corresponding to the breakdown of polymer chains, stabilizers, تولید کننده کامپاند پلیمری pigments, flame retardants, or impurities. Reclaimed plastics frequently include trace chemicals, leachables, or network modifiers that degrade at different temperatures, so several distinct mass-loss events occur.

After the run ends, analyze the data to identify key decomposition temperatures, such as the T_onset, maximum rate of degradation, and final char yield. Compare these values with those of newly manufactured polymer or reference samples to quantify material deterioration, contamination, or polymer mixing. A increased ash yield may indicate the incorporation of mineral reinforcements, while lower thermal stability suggests previous thermal exposure or chemical degradation.

Conduct a baseline run with an reference vessel under the identical parameters to eliminate environmental artifacts. Run triplicate trials to ensure reproducibility. Note the provenance, recycling history, and preparation procedures, as these factors critically alter TGA profiles. TGA offers a robust technique to assess degradation resistance and chemical makeup of recycled polymers, helping to optimize recycling workflows and quality control in recycling operations.