Crystallinity Transformation in Pulverized Polyphthalamide for Sustainable Polymer Engineering

Abstract:

Mechanical recycling of high-temperature semi-aromatic polyamides remains challenging due to their high melting temperatures and limited processability. In this study, secondary glass-fiber-reinforced polyphthalamide was processed by two mechanical size-reduction routes: conventional crushing and pulverization in an industrial high-speed dual-disc pulverizer. Structural and thermal changes were evaluated by Fourier Transform infrared spectroscopy, X-ray diffraction and differential scanning calorimetry. Fourier Transform infrared spectroscopy confirms that both routes preserve the polyphthalamide backbone, while the pulverized material shows subtle changes in the N-H and C=O regions consistent with partial reorganization of the hydrogen-bonding network. X-ray diffraction shows a decrease in apparent crystallinity from ~24.2% (crushed) to ~18.4% (pulverized), accompanied by an increase in average crystallite size from ~10.3 to ~12.8 nm, suggesting lamellar-scale restructuring. Differential scanning calorimetry analysis emphasizes the first heating as a probe of the as-processed condition: the pulverized secondary glass-fiber-reinforced polyphthalamide exhibits a lower melting enthalpy (≈17 J/g versus ≈23 J/g for the crushed reference) and a distinct cold-crystallization peak near 166 °C. This feature is not observed in the crushed material and disappears after melting and controlled cooling, whereas Tg and Tm remain largely unchanged. Overall, X-ray diffraction and differential scanning calorimetry consistently show that the pulverized powder differs from the crushed reference mainly in first-heating enthalpy and the appearance of cold crystallization, while Tg and Tm remain similar. From an application perspective, pulverized secondary glass-fiber-reinforced polyphthalamide is a fine, heat-stable recycled feedstock that can be reintroduced more readily into polyamide blends and compounds, providing a simple, solvent-free route to enhance the engineering value of recycled high-temperature polyphthalamide.

• Periodical: Materials Science Forum (Volume 1199)
• Pages: 127-135
• DOI: https://doi.org/10.4028/p-3aSQRS
• Online since: August 2026
• Authors: Yevhen Yekymov, Vladimir Lebedev*
• Keywords: Circular Materials, Crystallinity, DSC, Polyphthalamide, Pulverization, Sustainable Polymer Engineering, XRD

References

[1] V. Hirschberg, D. Rodrigue, Recycling of polyamides: Processes and conditions, Journal of Polymer Science 61 (2023) 1937–1958.

DOI: 10.1002/pol.20230154

[2] M.G. De Gortari, M. Misra, A.K. Mohanty, Polyphthalamide polymers: A review on synthesis, properties, and advance manufacturing and emerging applications, Journal of Applied Polymer Science 139 (2022).

DOI: 10.1002/app.52965

[3] M.Y. Kondo, L.S. Montagna, G.F. De Melo Morgado, A.L.G. De Castilho, L.A.P.D.S. Batista, E.C. Botelho, M.L. Costa, F.R. Passador, M.C. Rezende, M.V. Ribeiro, Recent advances in the use of Polyamide-based materials for the automotive industry, Polímeros 32 (2022).

DOI: 10.1590/0104-1428.20220042

[4] I.B. Amor, O. Klinkova, M. Baklouti, R. Elleuch, I. Tawfiq, Mechanical recycling and its effects on the physical and mechanical properties of polyamides, Polymers 15 (2023) 4561.

DOI: 10.3390/polym15234561

[5] Y. Zhang, M. Wang, D. Zhang, Y. Wang, L. Wang, Y. Qiu, L. Wang, T. Chen, L. Zhao, Crystallization and performance of polyamide blends comprising polyamide 4, polyamide 6, and their copolymers, Polymers 15 (2023) 3399.

DOI: 10.3390/polym15163399

[6] N. Yaghini, G.W.M. Peters, Modeling crystallization kinetics and resulting properties of polyamide 6, Macromolecules 54 (2021) 1894–1904.

DOI: 10.1021/acs.macromol.0c02588

[7] W. Lu, C. Wang, Y. Yi, M. Liao, J. Li, W. Wang, Synthesis and non-isothermal crystallization kinetics of polyamide 66 copolymers containing alicyclic structures, RSC Advances 15 (2025) 2900–2911.

DOI: 10.1039/d4ra08482a

[8] G. Tonsi, C. Maesani, M.A. Ortenzi, S. Alini, C. Pirola, The selective dissolution-precipitation recycling: A review on this alternative approach for the recovery of nylon-based waste materials, Waste Management 204 (2025) 114937.

DOI: 10.1016/j.wasman.2025.114937

[9] M.G. De Gortari, F. Wu, A.K. Mohanty, M. Misra, Evaluating the performance of a Semiaromatic/Aliphatic polyamide blend: the case for polyphthalamide (PPA) and polyamide 4,10 (PA410), Polymers 13 (2021) 3391.

DOI: 10.3390/polym13193391

[10] L. Zheng, M. Wang, Y. Li, Y. Xiong, C. Wu, Recycling and degradation of polyamides, Molecules 29 (2024) 1742.

[11] N. Castanha, F.B.H. Dantas, L.M. Júnior, Mechanical recycling of polyamides: a review, Trends in Food Science & Technology 162 (2025) 105107.

DOI: 10.1016/j.tifs.2025.105107

[12] J. Morales, D. Rodrigue, The effect of reprocessing and moisture on polyamide recycling: A focus on neat, composites, and blends, Macromolecular Materials and Engineering 310 (2024).

DOI: 10.1002/mame.202400304

[13] Wei, L. Li, S. Ding, N. Chen, S. Bai, S. Yang, Solid-State Shear Milling for Recycling Aluminum–Plastic Packaging waste: a sustainable solution for mixed plastic waste, Sustainability 15 (2023) 6144.

DOI: 10.3390/su15076144

[14] Y. Wei, Y. Luo, Z. Wang, M. Peng, G. Li, Y. Huang, Optimization of polyamide 1012 powder for laser powder bed fusion via complexation with metal ions, Additive Manufacturing 79 (2023) 103917.

DOI: 10.1016/j.addma.2023.103917

[15] O. Kabat, V. Sytar, K. Sukhyy, Antifrictional polymer composites based on aromatic polyamide and carbon black, Chemistry & Chemical Technology 12 (2018) 326–330.

DOI: 10.23939/chcht12.03.326

[16] O. Kabat, Y. Boiko, Polymer Composites Based on Aromatic Polyamide and Aramid Fiber for Heavy-Duty Friction and Sealing Units, Chemistry & Chemical Technology 19 (2025) 335–341.

DOI: 10.23939/chcht19.02.335

[17] F. Karimian, G. Karimi, M. Khorram, R. Daraeinejad, M.M. Abdi, Optimized design and fabrication of polyethylene glycol 1000/Polyamide 6 (PEG1000/PA6) nanofibers for phase change materials (PCMs) application, Chemistry & Chemical Technology 17 (2023) 386–396.

DOI: 10.23939/chcht17.02.386

[18] G. Strobl, The Physics of Polymers: Concepts for Understanding Their Structures and Behavior, third ed., Springer, Berlin, 2007.

[19] B. Wunderlich, Thermal Analysis of Polymeric Materials, first ed., Springer, Berlin, 2005.

[20] Y. Yekymov, V. Lebedev, T. Tykhomyrova, H. Cherkashina, A. Kariev, Design and research of a construction-grade engineering plastic based on recycled polyamides and polyphthalamides, IOP Conference Series Earth and Environmental Science 1499 (2025) 012016.

DOI: 10.1088/1755-1315/1499/1/012016