ESTONIAN ACADEMY
PUBLISHERS
eesti teaduste
akadeemia kirjastus
PUBLISHED
SINCE 1952
 
Proceeding cover
proceedings
of the estonian academy of sciences
ISSN 1736-7530 (Electronic)
ISSN 1736-6046 (Print)
Impact Factor (2022): 0.9
Behaviour of the very-low-temperature crystallization peak of linear low-density polyethylene; pp. 58–62
PDF | doi: 10.3176/proc.2009.1.10

Authors
Triinu Poltimäe, Elvira Tarasova, Andres Krumme, Arja Lehtinen, Anti Viikna
Abstract
The crystallization behaviour of Ziegler–Natta (ZN) and single-site catalyst based ethylene–1-butene and ethylene–1-hexene copolymers with different comonomer content were studied by differential scanning calorimetry. In addition to a high-temperature crystallization peak, and for ZN copolymers in addition to a low-temperature crystallization peak, quite often a very-low-temperature crystallization peak (VLTCP) was observed at temperatures in between approximately 330 and 345 K. It was found that the VLTCP temperature decreased with increasing comonomer content and did not depend on the type of catalyst used. The fractional degree of crystallinity calculated from the VLTCP was independent of the chemical nature and content of the comonomers present as well as of the polydispersity of molar mass within the used range of magnitudes. However, crystallinity as related to the area of the VLTCP was strongly catalyst type dependent and was higher for the single-site catalyst used compared to the ZN catalyst used.
References

  1. Pino, P., Oschwald, A., Ciardelli, F., Carlini, C., and Chiellini, E. Coordination Polymerization of α-Olefins (Chien, J. C. W., ed.). Elsevier, New York, 1975.

  2. Ziegler, K., Holzkamp, E., Breil, H., and Martin, H. Das Mülheimer Normaldruck-Polyäthylen-Verfahren. Angew. Chem., 1955, 541–547.
doi:10.1002/ange.19550671902

  3. Natta, G. Une nouvelle classe de polymeres d’α-olefines ayant une régularité de structure exceptionnelle. J. Polym. Sci., 1955, 16, 143–154.
doi:10.1002/pol.1955.120168205

  4. Hseih, E. T., Tso, C. C., Byers, J. D., Johnson, T. W., Fu, Q., and Cheng, S. Z. D. Intermolecular structural homogeneity of metallocene polyethylene copolymers.J. Macromol. Sci. Phys., 1997, 36, 615–628.
doi:10.1080/00222349708220445

  5. Flory, P. J. Theory of crystallization in copolymers. Trans. Faraday Soc., 1954, 51, 848–857.
doi:10.1039/tf9555100848

  6. Hussein, I. A. Nonisothermal crystallization kinetics of linear metallocene polyethylenes. J. Appl. Polym. Sci., 2008, 107, 2802–2809.
doi:10.1002/app.27392

  7. Mathot, V. B. F. Calorimetry and Thermal Analysis of Polymers (Mathot, V. B. F., ed.). Hanser Publishers, Munich, 1994.

  8. Mathot, V. B. F., Scherrenberg, R. L., and Pijpers, T. F. J. Metastability and order in linear, branched and copolymerized polyethylenes. Polymer, 1998, 39, 4541–4559.
doi:10.1016/S0032-3861(97)10306-8

  9. Minick, J., Moet, A., Hiltner, A., Baer, E., and Chum, S. P. Crystallization of very low density copolymers of ethylene with α-olefins. J. Appl. Polym. Sci., 1995, 58, 1371–1384.
doi:10.1002/app.1995.070580819

10. Zhang, F., Liu, J., Xie, F., Fu, Q., and He, T. Poly­dispersity of ethylene sequence length in metallocene ethylene/α-olefin copolymers. II. Influence on crystalliza­tion and melting behaviour. J. Appl. Polym. Sci. Polym. Phys., 2002, 40, 822–830.
doi:10.1002/polb.10146

11. Mirabella, F. M. Crystallization and melting of a poly­ethylene copolymer: in situ observation by atomic force microscopy. J. Appl. Polym. Sci., 2008, 108, 987–994.
doi:10.1002/app.27739

12. Kraack, H., Sirota, E. B., and Deutsch, M. Homogeneous crystal nucleation in short polyethylenes. Polymer, 2001, 42, 8225–8233.
doi:10.1016/S0032-3861(01)00308-1

13. Weber, C. H. M., Chiche, A., and Krausch, G. Single lamella nanoparticles of polyethylene. Nano Lett., 2007, 7, 2024–2029.
doi:10.1021/nl070859f

14. Wilfong, D. and Knight, G. W. Crystallization mecha­nisms for LLDPE and its fractions. J. Polym. Sci. Polym. Phys., 1990, 28, 861–870.
doi:10.1002/polb.1990.090280605

15. Kim, M. and Philips, P. J. Nonisothermal melting and crystallization studies of homogeneous ethylene/α-olefin random copolymers. J. Appl. Polym. Sci., 1998, 70, 1893–1905.
doi:10.1002/(SICI)1097-4628(19981205)70:10<1893::AID-APP4>3.3.CO;2-Y

16. Alamo, R. G. and Mandelkern, L. Thermodynamic and structural propeties of ethylene copolymers. Macro­molecules, 1989, 22, 1273–1277.
doi:10.1021/ma00193a045

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