Pyrolysis Kinetic Analysis of Decommissioned Photovoltaic Encapsulation Films

Research Article
Open access

Pyrolysis Kinetic Analysis of Decommissioned Photovoltaic Encapsulation Films

Zhexin Zhao 1 , Yunji Pang 2 , Tiejun Zhang 3* , Xi Jiang 4
  • 1 School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia Autonomous Region, China;     
  • 2 School of Chemistry and Chemical Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia Autonomous Region, China)    
  • 3 School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia Autonomous Region, China;     
  • 4 School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia Autonomous Region, China;     
  • *corresponding author hjgcztj@126.com
Published on 22 June 2025 | https://doi.org/10.54254/2753-8818/2025.24097
TNS Vol.118
ISSN (Print): 2753-8826
ISSN (Online): 2753-8818
ISBN (Print): 978-1-80590-211-9
ISBN (Online): 978-1-80590-212-6

Abstract

The resource utilization of decommissioned photovoltaic (PV) modules is the final stage of the PV industry chain and a critical step toward achieving sustainable development. Addressing the challenge of removing the encapsulation layer (EVA film) during the recycling process of retired PV modules, this study calculates the acetic acid content using thermogravimetric analysis (TGA) to clarify the thermal stability of EVA films under high-temperature conditions. Based on the thermal weight loss behavior of EVA films at four different heating rates (5 °C/min, 10 °C/min, 15 °C/min, and 20 °C/min), key parameters such as the onset and completion temperatures of pyrolysis and the temperature at maximum weight loss were determined. The Flynn-Wall-Ozawa method was used to construct a pyrolysis kinetic model, segmenting the pyrolysis reaction into different stages. Linear regression analysis was conducted at nine reaction conversion points to calculate the variation in activation energy across different stages. The results show that the vinyl acetate content in EVA films from decommissioned PV modules is significantly lower than the standard range, indicating reduced thermal stability. The pyrolysis process achieves a mass loss of over 95%, demonstrating the effectiveness of pyrolytic removal. As the heating rate increases, the thermogravimetric curve shifts toward higher temperatures, attributed to temperature lag caused by differences in heat transfer efficiency. According to the kinetic model, EVA pyrolysis can be divided into two stages: the first involving deacetylation and side-chain cleavage, and the second involving main-chain scission. The activation energy in the second stage is significantly higher than in the first, indicating that decomposition of the EVA main chain requires more energy.

Keywords:

Decommissioned photovoltaics, resource recovery, EVA film, pyrolysis, kinetic analysis

Zhao,Z.;Pang,Y.;Zhang,T.;Jiang,X. (2025). Pyrolysis Kinetic Analysis of Decommissioned Photovoltaic Encapsulation Films. Theoretical and Natural Science,118,1-9.
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References

[1]. Wang, M., Hu, Z. F., Bai, B., et al. (2024). A review on dissociation and resource utilization of decommissioned crystalline silicon photovoltaic modules. Journal of China Coal Society, 49(10), 4188–4202.

[2]. Doni, A., & Dughiero, F. (2012). Proceedings of the 38th IEEE Photovoltaic Specialists Conference (pp. 000757–000762). Austin, TX, USA.

[3]. Dong, L., Liu, J. Y., Zhou, X. Y., et al. (2016). Thermal treatment and products analysis of EVA in waste crystalline silicon photovoltaic modules. Environmental Pollution & Control, 38(10), 61–66.

[4]. Jin, G. T. (1995). The theory and progress of polymer chemistry [M]. China Sinopec Press.

[5]. Ozawa, T. (1986). Non-isothermal kinetics and generalized time. Thermochimica Acta, 100(1), 109–118.

[6]. Flynn, J. H., & Wall, L. A. (1966). General treatment of the thermogravimetry of polymers. Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 70(6), 487.

[7]. Xu, C., Lin, B., Yuan, X., et al. (2019). Recycling of waste crystalline silicon photovoltaic module. Chinese Journal of Environmental Engineering, 13(06), 1417–1424.

[8]. Dong, L., Zhou, X. Y., Liu, J. Y., et al. (2020). Research on thermogravimetric dynamics and products distribution of EVA in waste photovoltaic modules. Acta Energiae Solaris Sinica, 41(04), 14–19.

[9]. Bugada, D. C., & Rudin, A. (1992). Molecular structure and melting behaviour of ethylene-vinyl acetate copolymers. European Polymer Journal, 28(3), 219–227.

Cite this article

Zhao,Z.;Pang,Y.;Zhang,T.;Jiang,X. (2025). Pyrolysis Kinetic Analysis of Decommissioned Photovoltaic Encapsulation Films. Theoretical and Natural Science,118,1-9.

Data availability

The datasets used and/or analyzed during the current study will be available from the authors upon reasonable request.

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About volume

Volume title: Proceedings of the 3rd International Conference on Environmental Geoscience and Earth Ecology

ISBN：978-1-80590-211-9(Print) / 978-1-80590-212-6(Online)
Editor：Alan Wang
Conference website: https://2025.icegee.org/
Conference date: 10 April 2025
Series: Theoretical and Natural Science
Volume number: Vol.118
ISSN：2753-8818(Print) / 2753-8826(Online)

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References

[1]. Wang, M., Hu, Z. F., Bai, B., et al. (2024). A review on dissociation and resource utilization of decommissioned crystalline silicon photovoltaic modules. Journal of China Coal Society, 49(10), 4188–4202.

[2]. Doni, A., & Dughiero, F. (2012). Proceedings of the 38th IEEE Photovoltaic Specialists Conference (pp. 000757–000762). Austin, TX, USA.

[3]. Dong, L., Liu, J. Y., Zhou, X. Y., et al. (2016). Thermal treatment and products analysis of EVA in waste crystalline silicon photovoltaic modules. Environmental Pollution & Control, 38(10), 61–66.

[4]. Jin, G. T. (1995). The theory and progress of polymer chemistry [M]. China Sinopec Press.

[5]. Ozawa, T. (1986). Non-isothermal kinetics and generalized time. Thermochimica Acta, 100(1), 109–118.

[6]. Flynn, J. H., & Wall, L. A. (1966). General treatment of the thermogravimetry of polymers. Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 70(6), 487.

[7]. Xu, C., Lin, B., Yuan, X., et al. (2019). Recycling of waste crystalline silicon photovoltaic module. Chinese Journal of Environmental Engineering, 13(06), 1417–1424.

[8]. Dong, L., Zhou, X. Y., Liu, J. Y., et al. (2020). Research on thermogravimetric dynamics and products distribution of EVA in waste photovoltaic modules. Acta Energiae Solaris Sinica, 41(04), 14–19.

[9]. Bugada, D. C., & Rudin, A. (1992). Molecular structure and melting behaviour of ethylene-vinyl acetate copolymers. European Polymer Journal, 28(3), 219–227.

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