Thermogravimetric analyzer for decomposition testing of PVC plastics

Thermogravimetric analysis (TGA) is an important thermal analysis technology equipment that studies the thermal stability, thermal decomposition process, and reaction kinetics of substances by measuring the change in mass of substances with temperature under programmed temperature control. In the research of PVC plastics, thermogravimetric analysis can be used to reveal the characteristics and laws of PVC thermal decomposition, providing key theoretical basis for its recycling and harmless treatment. Through thermogravimetric analysis equipment, the starting temperature, continuous loss rate, and weight loss during the thermal decomposition of PVC can be determined. This information has important guiding significance for optimizing PVC recycling processes and environmental treatment methods.

1、 Thermal decomposition characteristics of PVC

The pyrolysis process of the PVC plastic tested this time exhibits typical two-stage decomposition characteristics, which is significantly different from other general plastics or other general PVC. Compared with other common plastics, PVC has lower thermal stability, and its initial decomposition temperature is usually between 200-300 ℃. In an inert atmosphere (such as nitrogen), the residual material after PVC pyrolysis is mainly carbon black, while in an oxidizing atmosphere (such as air), it will further oxidize to form metal oxide ash. This atmosphere dependent decomposition behavior makes atmosphere selection particularly crucial in PVC thermogravimetric analysis.

2、 Experimental steps

1. Sample preparation

Sample morphology treatment: The powder material should be evenly spread in a thin layer at the bottom of the crucible, and the sample particles should be prepared as small as possible; It is recommended to cut the block material into thin slices or granules, and evenly distribute them at the bottom of the crucible;

Sample quality: The sample quality is usually controlled between 10-20 milligrams, evenly distributed, avoiding accumulation and clumping, and filling the crucible with about one-third of its volume.

2. Experimental equipment

DZ-TGA201 Thermogravimetric Analyzer

3. Experimental parameter settings

Temperature program: Set the cut-off temperature and rate according to the characteristics and purpose of the sample. This time, we set a temperature cutoff of 700 ℃ and a heating rate of 20, using a nitrogen protected atmosphere for program heating throughout the entire process.

4. Place the sample

Place the prepared high-temperature engineering plastic sample crucible in the sample chamber of the thermogravimetric analyzer to ensure that the sample is placed smoothly. Start the instrument and raise the temperature according to the set temperature program. The instrument will continuously record the mass change of the sample, generating thermogravimetric and DTG curves. During the experiment, it is important to closely monitor the operating status and curve changes of the instrument to ensure the smooth progress of the experiment.

5. Experimental diagram

The thermal decomposition characteristics of PVC plastic hoses were studied through thermogravimetric analysis, and it was found that the pyrolysis process mainly consists of two stages. The first stage of di mainly focuses on the temperature range of 200 ℃ -450 ℃, mainly involving the precipitation of chlorine (HCL), release of small molecule additives, and most plasticizers and flame retardants. The weight loss ratio is about 15%, accompanied by the breaking and cross-linking of molecular chains, forming conjugated polyene structures. The second stage mainly focuses on the fracture and recombination reactions of carbon hydrogen primary bonds between 450 ℃ and 700 ℃.

3、 Application and Conclusion

1. Application of Thermogravimetric Analyzer

Thermogravimetric analysis has wide application value in the material research and development, quality control, and safety evaluation of PVC hoses. During the material development phase, TGA can assist formulation engineers in evaluating the impact of different additive systems on thermal stability and optimizing material formulations.

2. Experimental conclusion

Thermogravimetric analyzer is a powerful tool for studying the decomposition behavior of PVC plastic hoses, which can provide key information such as material thermal stability, composition, and decomposition kinetics. By analyzing the TGA curve, it can be identified that PVC hoses undergo a two-stage decomposition process: dechlorination reaction at low temperatures and main chain fracture at high temperatures. These pieces of information are of significant value for material research and development, quality control, safety assessment, and waste disposal. And this device can be combined with other analytical methods such as infrared spectroscopy, mass spectrometry, etc., so that we can have a more comprehensive understanding of the chemical changes and product distribution during the PVC pyrolysis process, providing a deeper scientific basis for material design and environmental sustainability development.