Advances in materials Research

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Structure-property relations for polymer melts: comparison of linear low-density polyethylene and isotactic polypropylene

  • Drozdov, A.D. (Department of Chemical Engineering, West Virginia University) ;
  • Al-Mulla, A. (Department of Chemical Engineering, Kuwait University) ;
  • Gupta, R.K. (Department of Chemical Engineering, West Virginia University)
  • Received : 2012.07.02
  • Accepted : 2012.09.05
  • Published : 2012.12.25
⟨ Previous Next ⟩

Abstract

Results of isothermal torsional oscillation tests are reported on melts of linear low density polyethylene and isotactic polypropylene. Prior to rheological tests, specimens were annealed at various temperatures ranging from $T_a$ = 180 to $310^{\circ}C$ for various amounts of time (from 30 to 120 min). Thermal treatment induced degradation of the melts and caused pronounced decreases in their molecular weights. With reference to the concept of transient networks, constitutive equations are developed for the viscoelastic response of polymer melts. A melt is treated as an equivalent network of strands bridged by junctions (entanglements and physical cross-links). The time-dependent response of the network is modelled as separation of active strands from and merging of dangling strands with temporary nodes. The stress-strain relations involve three adjustable parameters (the instantaneous shear modulus, the average activation energy for detachment of active strands, and the standard deviation of activation energies) that are determined by matching the dependencies of storage and loss moduli on frequency of oscillations. Good agreement is demonstrated between the experimental data and the results of numerical simulation. The study focuses on the effect of molecular weight of polymer melts on the material constants in the constitutive equations.

Keywords

References

  1. Barakos, G., Mitsoulis, E., Tzoganakis, C. and Kajiwara, T. (1996), "Rheological characterization of controlledrheology polypropylenes using integral constitutive equations", J. Appl. Polym. Sci., 59(3), 543-556. https://doi.org/10.1002/(SICI)1097-4628(19960118)59:3<543::AID-APP21>3.0.CO;2-T
  2. Berzin, F., Vergnes, B. and Delamare, L. (2001), "Rheological behavior of controlled-rheology polypropylenes obtained by peroxide-promoted degradation during extrusion: Comparison between homopolymer and copolymer", J. Appl. Polym. Sci., 80(8), 1243-1252. https://doi.org/10.1002/app.1210
  3. Carrot, C., Revenu, P. and Guillet, J. (1996), "Rheological behavior of degraded polypropylene melts: From MWD to dynamic moduli", J. Appl. Polym. Sci., 61(11), 1887-1897. https://doi.org/10.1002/(SICI)1097-4628(19960912)61:11<1887::AID-APP4>3.0.CO;2-F
  4. Combs, R.L., Slonaker, D.F. and Coover, H.W. (1969), "Effects of molecular weight distribution and branching on rheological properties of polyolefin melts", J. Appl. Polym. Sci., 13(3), 519-534. https://doi.org/10.1002/app.1969.070130312
  5. Derrida, B. (1980), "Random-energy model: Limit of a family of disordered models", Phys. Rev. Lett., 45(2), 79-82. https://doi.org/10.1103/PhysRevLett.45.79
  6. Dlubek, G., Bamford, D., Rodriguez-Gonzalez, A., Bornemann, S., Stejny, J., Schade, B., Alam, M.A. and Arnold, M. (2002), "Free volume, glass transition, and degree of branching in metallocene-based propylene/${\alpha}$-olefin copolymers: Positron lifetime, density, and differential scanning calorimetric studies", J. Polym. Sci. Pol. Phys., 40(5), 434-453. https://doi.org/10.1002/polb.10108
  7. Doi, M. and Edwards, S.F. (1986), The theory of polymer dynamics, Oxford University Press, New York.
  8. Drozdov, A.D. and Christiansen, J.D. (2003), "The effect of annealing on the nonlinear viscoelastic response of isotactic polypropylene", Polym. Eng. Sci., 43(4), 946-959. https://doi.org/10.1002/pen.10078
  9. Drozdov, A.D. and Christiansen, J.D. (2003), "The effect of annealing on the elastoplastic and viscoelastic responses of isotactic polypropylene", Comp. Mater. Sci., 27(4), 403-422. https://doi.org/10.1016/S0927-0256(03)00040-5
  10. Drozdov, A.D., Agrawal, S. and Gupta, R.K. (2005), "The effect of temperature on the viscoelastic response of polymer melts", Int. J. Eng. Sci., 43(3-4), 304-320. https://doi.org/10.1016/j.ijengsci.2004.08.009
  11. Drozdov, A.D. and Yuan, Q. (2003), "The viscoelastic and viscoplastic behavior of low-density polyethylene", Int. J. Solids Struct., 40(10), 2321-2342. https://doi.org/10.1016/S0020-7683(03)00074-X
  12. Drozdov, A.D. and Yuan, Q. (2003), "Effect of annealing on the viscoelastic and viscoplastic responses of lowdensity polyethylene", J. Polym. Sci. Pol. Phys., 41(14), 1638-1655. https://doi.org/10.1002/polb.10507
  13. Drozdov, A.D. (2003), "Kinetic equations for thermal degradation of polymers", arXiv:cond-mat/0309677v1[cond-mat.mtrl-sci].
  14. Eckstein, A., Friedrich, C., Lobbrecht, A., Spitz, R. and Mülhaupt, R. (1997), "Comparison of the viscoelastic properties of syndio- and isotactic polypropylenes", Acta Polym., 48(1-2), 41-46. https://doi.org/10.1002/actp.1997.010480107
  15. Fayolle, B., Audouin, L. and Verdu, J. (2002), "Initial steps and embrittlement in the thermal oxidation of stabilised polypropylene films", Polym. Degrad. Stabil., 75(1), 123-129. https://doi.org/10.1016/S0141-3910(01)00211-7
  16. Ferry, J.D. (1980), Viscoelastic properties of polymers, 3rd Ed., Wiley, New York.
  17. Fujiyama, M., Kitajima, Y. and Inata, H. (2002), "Rheological properties of polypropylenes with different molecular weight distribution characteristics", J. Appl. Polym. Sci., 84(12), 2128-2141. https://doi.org/10.1002/app.10375
  18. Fujiyama, M. and Inata, H. (2002), "Rheological properties of metallocene isotactic polypropylenes", J. Appl. Polym. Sci., 84(12), 2157-2170. https://doi.org/10.1002/app.10482
  19. Gao, J.M., Lu, Y.J., Wei, G.S., Zhang, X.H., Liu, Y.Q. and Qiao, J.L. (2002), "Effect of radiation on the crosslinking and branching of polypropylene", J. Appl. Polym. Sci., 85(8), 1758-1764. https://doi.org/10.1002/app.10716
  20. Gao, Z., Kaneko, T., Amasaki, I. and Nakada, M. (2003), "A kinetic study of thermal degradation of polypropylene", Polym. Degrad. Stabil., 80(2), 269-274. https://doi.org/10.1016/S0141-3910(02)00407-X
  21. Gennes, P.G. (1979), Scaling concepts in polymer physics, Cornell University Press, Ithaca, N.Y.
  22. Graessley, W. (1982), "Entangled linear, branched and network polymer systems - Molecular theories", Adv. Polym Sci., 47, 67-117. https://doi.org/10.1007/BFb0038532
  23. Green, M.S. and Tobolsky, A.V. (1946), "A new approach to the theory of relaxing polymeric media", J. Chem. Phys., 14(2), 80-92. https://doi.org/10.1063/1.1724109
  24. Horrocks, A.R., Valinejad, K. and Crighton, J.S. (1994), "Demonstration of the possible competing effects of oxidation and chain scission in orientated and stressed polypropylenes", J. Appl. Polym. Sci., 54(5), 593-600. https://doi.org/10.1002/app.1994.070540510
  25. Iijima, M. and Strobl, G. (2000), "Isothermal crystallization and melting of isotactic polypropylene analyzed by time- and temperature-dependent small-angle X-ray scattering experiments", Macromolecules, 33(14), 5204-5214. https://doi.org/10.1021/ma000019m
  26. Kim, Y.C., Yang, K.S. and Choi, C.H. (1998), "Study of the relationship between shear modification and melt fracture in extrusion of LDPE", J. Appl. Polym. Sci., 70(11), 2187-2195. https://doi.org/10.1002/(SICI)1097-4628(19981212)70:11<2187::AID-APP13>3.0.CO;2-5
  27. Kim, M.H., Londono, J.D. and Habenschuss, A. (2000), "Structure of molten stereoregularpolyolefins with different side-chain sizes: Linear polyethylene, polypropylene, poly(1-butene), and poly(4-methyl-1-pentene)", J. Polym. Sci. Pol. Phys., 38, 2480-2485. https://doi.org/10.1002/1099-0488(20000915)38:18<2480::AID-POLB150>3.0.CO;2-8
  28. Kumar, G.S., Kumar, V.R. and Madras, G. (2002), "Continuous distribution kinetics for the thermal degradation of LDPE in solution", J. Appl. Polym. Sci., 84(4), 681-690. https://doi.org/10.1002/app.2344
  29. Lodge, A.S. (1968), "Constitutive equations from molecular network theories for polymer solutions", Rheol. Acta, 7(4), 379-392. https://doi.org/10.1007/BF01984856
  30. Matsuda, H., Aoike, T., Uehara, H., Yamanobe, T. and Komoto, T. (2001), "Overlapping of different rearrangement mechanisms upon annealing for solution-crystallized polyethylene", Polymer, 42(11), 5013-5021. https://doi.org/10.1016/S0032-3861(00)00893-4
  31. Mader, D., Heinemann, J., Walter, P. and Mulhaupt, R. (2000), "Influence of n-alkyl branches on glass-transition temperatures of branched polyethylenes prepared by means of metallocene- and palladium-based catalysts", Macromolecules, 33(4), 1254-1261. https://doi.org/10.1021/ma991096o
  32. Perez, C.J., Cassano, G.A., Valles, E.M., Quinzani, L.M. and Failla, M.D. (2003), "Tensile mechanical behavior of linear high-density polyethylenes modified with organic peroxide", Polym. Eng. Sci., 43(9), 1624-1633. https://doi.org/10.1002/pen.10136
  33. Rangarajan, P., Bhattacharyya, D. and Grulke, E. (1998), "HDPE liquefaction: Random chain scission model", J. Appl. Polym. Sci., 70(6), 1239-1251. https://doi.org/10.1002/(SICI)1097-4628(19981107)70:6<1239::AID-APP20>3.0.CO;2-T
  34. Sugimoto, M., Masubuchi, Y., Takimoto, J. and Koyama, K. (2001), "Melt rheology of polypropylene containing small amounts of high molecular weight chain. I. Shear flow", J. Polym. Sci. Pol. Phys., 39(21), 2692-2704. https://doi.org/10.1002/polb.10012
  35. Sugimoto, M., Masubuchi, Y., Takimoto, J. and Koyama, K. (2001), "Melt rheology of polypropylene containing small amounts of high-molecular-weight chain. 2. uniaxial and biaxial extensional flow", Macromolecules, 34(17), 6056-6063. https://doi.org/10.1021/ma0015525
  36. Sweeney, J., Collins, T.L.D., Coates, P.D. and Duckett, R.A. (1999), "High-temperature large strain viscoelastic behavior of polypropylene modeled using an inhomogeneously strained network", J. Appl. Polym. Sci., 72(4), 563-575. https://doi.org/10.1002/(SICI)1097-4628(19990425)72:4<563::AID-APP13>3.0.CO;2-#
  37. Tanaka, F. and Edwards, S.F. (1992), "Viscoelastic properties of physically cross-linked networks - transient network theory"; Macromolecules, 25(5), 1516-1523. https://doi.org/10.1021/ma00031a024
  38. Tiemblo, P., Gomez-Elvira, J.M., Beltran, S.G., Matisova-Rychla, L. and Rychly, J. (2002), "Melting and a Relaxation Effects on the Kinetics of Polypropylene Thermooxidation in the Range $80170^{\circ}C$", Macromolecules, 35(15), 5922-5926. https://doi.org/10.1021/ma0119373
  39. Van Prooyen, M., Bremner, T. and Rudin, A. (1994), "Mechanism of shear modification of low density polyethylene", Polym. Eng. Sci., 34(7), 570-579. https://doi.org/10.1002/pen.760340705
  40. Wang, X., Tzoganakis, C. and Rempel, G. L. (1996), "Chemical modification of polypropylene with peroxide/pentaerythritoltriacrylate by reactive extrusion", J. Appl. Polym. Sci., 61(8), 1395-1404. https://doi.org/10.1002/(SICI)1097-4628(19960822)61:8<1395::AID-APP21>3.0.CO;2-X
  41. Yamamoto, M. (1956), "The visco-elastic properties of network structure I. general formalism", J. Phys. Soc. Jpn., 11(4), 413-421. https://doi.org/10.1143/JPSJ.11.413

Cited by

  1. Fiber Reinforced Polymer and Polypropylene Composite Retrofitting Technique for Masonry Structures vol.7, pp.12, 2015, https://doi.org/10.3390/polym7050963
  2. A comparative analysis of sheeting die geometries using numerical simulations vol.5, pp.2, 2020, https://doi.org/10.12989/acd.2020.5.2.111