Journal of Thermal Analysis and Calorimetry

, Volume 138, Issue 4, pp 2399–2408 | Cite as

Differential scanning calorimetry—a powerful tool for the determination of morphological features of the recycled polypropylene

  • Liana Baltes
  • Liviu Costiuc
  • Silvia PatachiaEmail author
  • Mircea Tierean


In order to be recycled, polymers with different molecular masses, designed to be initially processed by different technologies such as thermoforming, injection or blow molding, are collected together. The melt viscosity of this material mixture will depend on the ratio of polymers having different molecular characteristics. The possibility of re-processing implies the use of higher range of temperature or the use of different additives to adjust the melt viscosity. In these conditions, the quality of recycled goods could be affected. This study presents the results obtained by differential scanning calorimetry analysis of some polypropylene-based samples coming from the real waste stream collection (conventional samples) as well as of selected polymers from this stream based on the processing technology and of different brand packages from each of the above-mentioned classified fractions. Based on the thermal data (Tm, Tc, ΔHm, ΔHc and the melting and crystallization curve characteristics), morphological features of the recycled polypropylene, such as crystallinity degree of the initial recycled and re-crystallized polymers (Xm, Xc), melting and crystallization rates (vm, vc), lamellae thickness, and number of tie molecules, were determined, and the prediction of the maximal Young’s modulus was made. This study evidenced that processing technology of the polymers in fresh state or as recycled material strongly influenced the product morphology and, as a consequence, the predicted mechanical properties. By comparing the conventional recycled polymers with the injection-molded mix of virgin polymers, the first one exhibited a lower crystallinity with about 22%, approximately the same lamella thickness, the crystals’ polydispersity higher with about 10% and the Young’s modulus lower with about 22%.


Polypropylene Wastes Processing technologies DSC Crystallinity Lamella thickness Young’s modulus 



We acknowledge the contribution of Erasmus + master student Alexandra Rusanescu, from Transilvania University of Brasov, Romania, and master student Emma P.A. van Bruggen, from Delft University of Technology, the Netherlands, which prepared the samples used in this study under the kind and competent supervision of Prof. Dr. Peter C. Rem, from Delft University of Technology, Civil Engineering and Geosciences Faculty.


  1. 1.
    Satilla C, Cafiero L, De Angelis D, La Marca F, Tuffi R, Vecchio Ciprioti S. Thermal and catalytic pyrolysis of a mixture of plastics from small waste electrical and electronic equipment (WEEE). Waste Manag. 2016;54:143–52.CrossRefGoogle Scholar
  2. 2.
    Costiuc L, Tierean M, Baltes L, Patachia S. Experimental investigation on the heat of combustion for solid plastic waste mixtures. Environ Eng Manag J. 2015;14(6):1295–302.CrossRefGoogle Scholar
  3. 3.
    Costiuc L, Baltes L, Patachia S, Tierean M, Lunguleasa A. Influence of reprocessing by melt-mixing and thermo-formation of polyolefin fractions, separated from wastes, on their calorific power. Bulg Chem Commun. 2018;50:165–71.Google Scholar
  4. 4.
    Stromberg E, Karlsson S. The design of a test protocol to model the degradation of polyolefins during recycling and service life. J Appl Polym Sci. 2009;112:1835–44.CrossRefGoogle Scholar
  5. 5.
    Blanco I, Siracusa V. Kinetic study of the thermal and thermo-oxidative degradations of polylactide-modified films for food packaging. J Therm Anal Calorim. 2013;112(3):1171–7.CrossRefGoogle Scholar
  6. 6.
    Maddah HA. Polypropylene as a promising plastic: a review. Am J Polym Sci. 2016. Scholar
  7. 7.
    Zhang C, Yi X-S, Asai S, Sumita M. Morphology, crystallization and melting behaviors of isotactic polypropylene/high density polyethylene blend: effect of the addition of short carbon fiber. J Mater Sci. 2000;35(3):673–83.CrossRefGoogle Scholar
  8. 8.
    Bourbigot S, Garnier L, Revel B, Duquesne S. Characterization of the morphology of iPP/sPP blends with various compositions. Express Polym Lett. 2012. Scholar
  9. 9.
    Varga J. Crystallization, melting and supermolecular structure of isotactic polypropylene. In: Karger-Kocsis J, editor. Polypropylene: structure, blends and composites. London: Chapmann&Hall; 1995. p. 56–115.CrossRefGoogle Scholar
  10. 10.
    Varga J. β-Modification of isotactic polypropylene: preparation, structure, processing, properties, and application. J Macromol Sci B. 2002;41:1121–71. Scholar
  11. 11.
    Padden FJ, Keith HD. Evidence for a second crystal form of polypropylene. Jpn J Appl Phys. 1959;30:1479–84. Scholar
  12. 12.
    Natta G, Corradini P. Structure and properties of isotactic polypropylene. Nuovo Cimento. 1960;15:40–51. Scholar
  13. 13.
    Meille SV, Ferro DR, Bruckner S, Lovinger AJ, Padden FJ. Structure of beta-isotactic polypropylene-a long-standing structural puzzle. Macromolecules. 1994;27:2615–22.CrossRefGoogle Scholar
  14. 14.
    Lotz B, Wittmann JJ, Lovinger AJ. Structure and morphology of poly(prolylenes): a molecular analysis. Polymer. 1996;37:4979–92.CrossRefGoogle Scholar
  15. 15.
    Wunderlich B. Macromolecular physics: crystal nucleation, growth, annealing. London: Academic Press Inc.; 1979.Google Scholar
  16. 16.
    Eagan JM, Xu J, Di Girolamo R, Thurber CM, Macosko CW, LaPointe AM, Bates FS, Coates GW. Combining polyethylene and polypropylene: enhanced performance with PE/iPP multiblock polymers. Science. 2017. Scholar
  17. 17.
    Brandrup J, Immergut EH, Grulke EA, Abe A, Bloch DR. Polymer handbook. 4th ed. New York: Wiley; 2005.Google Scholar
  18. 18.
    Perrin-Sarazin F, Ton-That MT, Bureau MN, Denault J. Micro- and nano-structure in polypropylene/clay nanocomposites. Polymer. 2005;46:11624–34. Scholar
  19. 19.
    Karger-Kocsis J, Csikai I. Skin-core morphology and failure of injection-molded specimens of impact-modified polypropylene blends. Polym Eng Sci. 1987;27:241–53.CrossRefGoogle Scholar
  20. 20.
    Wang SW, Yang W, Xu YJ, Xie BH, Yang MB, Peng XF. Crystalline morphology of beta-nucleated controlled-rheology polypropylene. Polym Test. 2008;27:638–44. Scholar
  21. 21.
    Addink EJ, Beintema J. Polymorphism of crystalline polypropylene. Polymer. 1961;2:185–93.CrossRefGoogle Scholar
  22. 22.
    Phillips PJ, Mezghani K. Polypropylene, isotactic (polymorphism). In: Salamon JC, editor. The polymeric materials encyclopedy. Boca Raton: CRC Press; 1996. p. 6637–49.Google Scholar
  23. 23.
    Nitta KH, Takayanagi M. Role of tie molecules in the yielding deformation of isotactic polypropylene. J Polym Sci, Part B: Polym Phys. 1999;37:357–68.CrossRefGoogle Scholar
  24. 24.
    Nitta KH, Takayanagi M. Tensile yield of isotactic polypropylene in terms of a lamellar-cluster model. J Polym Sci, Part B: Polym Phys. 2000;38:1037–44.CrossRefGoogle Scholar
  25. 25.
    Wunderlich B. Thermal analysis of polymeric materials. Berlin: Springer; 2005.Google Scholar
  26. 26.
    Furushima Y, Nakada M, Murakami M, Yamane T, Toda A, Schick C. Method for calculation of the lamellar thickness distribution of not-reorganized linear polyethylene using fast scanning calorimetry in heating. Macromolecules. 2015;48(24):8831–7.CrossRefGoogle Scholar
  27. 27.
    Horváth Z. Correlation between molecular architecture and properties in semicrystalline polypropylene. PhD thesis, Published by Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest; 2014.Google Scholar
  28. 28.
    Horváth Z, Menyhárd A, Doshev P, Gahleitner M, Tranninger C, Kheirandish S, Varga J, Pukánszky B. Effect of molecular architecture on the crystalline structure and stiffness of iPP homopolymers: modeling based on annealing experiments. J Appl Polym Sci. 2013;130:3365–73.CrossRefGoogle Scholar
  29. 29.
    Menyhárd A, Suba P, László Z, Fekete HM, Mester ÁO, Horváth Z, Vörös G, Varga J, Móczó J. Direct correlation between modulus and the crystalline structure in isotactic polypropylene. Express Polym Lett. 2015;9:308–20.CrossRefGoogle Scholar
  30. 30.
    Molnár J, Jelinek A, Maloveczky A, Móczó J, Menyhárd A. Prediction of tensile modulus of semicrystalline polymers from a single melting curve recorded by calorimetry. J Therm Anal Calorim. 2018;134:401–8.CrossRefGoogle Scholar
  31. 31.
    Clark EJ, Hoffman JD. Regime lll crystallization in polypropylene. Macromolecules. 1984;17:878–85.CrossRefGoogle Scholar
  32. 32.
    Pukánszky B, Mudra I, Staniek P. Relation of crystalline structure and mechanical properties of nucleated polypropylene. J Vinyl Addit Technol. 1997;3:53–7.CrossRefGoogle Scholar

Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  1. 1.Materials Engineering and Welding DepartmentTransilvania University of BrasovBrasovRomania
  2. 2.Mechanical Engineering DepartmentTransilvania University of BrasovBrasovRomania
  3. 3.Product Design, Mechatronics and Environmental Protection DepartmentTransilvania University of BrasovBrasovRomania

Personalised recommendations