Influence of annealing on anisotropic crystalline structure of HDPE cast films

Document Type: Original research

Authors

1 Faculty of Processing, Iran Polymer and Petrochemical Institute, P.O. Box 14975/112, Tehran, Iran

2 Leibniz-Institut für Polymerforschung Dresden e. V., Hohe Str. 6, D-01069 Dresden, Germany

Abstract

High density polyethylene (HDPE) films were produced using cast film extrusion process with different draw ratios, ranging from 16.9 to 148.8. Morphology, crystallinty and orientation state of crystalline and amorphous phases of the cast films were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and polarized Fourier transform infrared spectroscopy (FTIR) analyses, respectively. The anisotropic crystalline structures of row-nucleated lamellar morphology were observed for the films produced with high draw ratios. The crystalline phase axes orientation functions were found to be significantly dependent on the applied draw ratios. As expected, annealing increased the crystallinity and melting point temperature (Tm) of the cast films and on the other hand, it also enhanced the crystalline phase orientation. However, the results revealed that annealing also promoted non-twisted lamellar structures, since it increased fc values (c-axis orientation function) and decreased fa values (a-axis orientation function) simultaneously. Additionally, it was found that the annealing induced enhancement in c-axis orientation function was more significant for the cast films with lower draw ratios, therefore, it was dependent on the draw ratio.

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  1. Nogales A, Hsiao BS, Somani RH, Srinivas S, Tsou AH, Balta-Calleja FJ, Ezquerra TA (2001) Shear-induced crystallization of isotactic polypropylene with different molecular weight distributions: In situ small-and wide-angle X-ray scattering studies. Polymer 42: 5247-5256
  2. Sadeghi F, Ajji A, Carreau P (2005) Study of polypropylene morphology obtained from blown and cast film processes: Initial morphology requirements for making membranes porous by stretching. J Plast Film Sheet 21: 199-216
  3. Tabatabaei SH, Carreau PJ, Ajji A (2009) Effect of processing on the crystalline orientation, morphology, and mechanical properties of polypropylene cast films and microporous membrane formation. Polymer 50: 4228-4240
  4. Seki M, Thurman DW, Oberhauser JP, Kornfield JA (2002) Shear-mediated crystallization of isotactic polypropylene: The role of long chain-long chain overlap. Macromolecules 35: 2583- 2594
  5. Bafna A, McFaddin D, Beaucage G, Merrick- Mack J, Mirabella FM (2007) Integrated mechanism for the morphological structure development in HDPE melt-blown and machine-direction-oriented films. J Polym Sci B: Polym Phys 45: 1834-1844
  6. Prasad A, Shroff R, Rane S, Beaucage G (2001) Morphological study of HDPE blown films by SAXS, SEM and TEM: A relationship between the melt elasticity parameter and lamellae orientation. Polymer 42: 3103-3113
  7. Lee S-Y, Park S-Y, Song H-S (2007) Effects of melt-extension and annealing on row-nucleated lamellar crystalline structure of HDPE films. J Appl Polym Sci 103: 3326-3333
  8. Hu B, Lei C, Xu R, Shi W, Cai Q, Mo H, Chen C (2013) Influence of melt-draw ratio on the structure and properties of poly (vinylidiene fluoride) cast film. J Plast Film Sheet 30: 300-313
  9. Sadeghi F, Ajji A, Carreau PJ (2007) Analysis of row nucleated lamellar morphology of polypropylene obtained from the cast film process: Effect of melt rheology and process conditions. Polym Eng Sci 47: 1170-1178
  10. Yu T-H,Wilkes GL (1996) Orientation determination and morphological study of high density polyethylene (HDPE) extruded tubular films: Effect of processing variables and molecular weight distribution. Polymer 37: 4675- 4687
  11. Zhang X, Elkoun S, Ajji A, Huneault M (2004) Oriented structure and anisotropy properties of polymer blown films: HDPE, LLDPE and LDPE. Polymer 45: 217-229
  12. Schrauwen B, Breemen Lv, Spoelstra A, Govaert L, Peters G, Meijer H (2004) Structure, deformation, and failure of flow-oriented semicrystalline polymers. Macromolecules 37: 8618-8633
  13. Hedesiu C, Demco DE, Kleppinger R, Buda AA, Blümich B, Remerie K, Litvinov VM (2007) The effect of temperature and annealing on the phase composition, molecular mobility and the thickness of domains in high-density polyethylene. Polymer 48: 763-777
  14. Hedesiu C, Demco D, Kleppinger R, Poel GV, Gijsbers W, Blümich B, Remerie K, Litvinov V (2007) Effect of temperature and annealing on the phase composition, molecular mobility, and the thickness of domains in isotactic polypropylene studied by proton solid-state NMR, SAXS, and DSC. Macromolecules 40: 3977-3989
  15. Bai H, Luo F, Zhou T, Deng H, Wang K, Fu Q (2011) New insight on the annealing induced microstructural changes and their roles in the toughening of β-form polypropylene. Polymer 52: 2351-2360
  16. Johnson MB, Wilkes GL (2002) Microporous membranes of isotactic poly (4-methyl-1- pentene) from a melt-extrusion process. II. Effects of thermal annealing and stretching on porosity. J Appl Polym Sci 84: 1076-1100
  17. Johnson MB, Wilkes GL (2002) Microporous membranes of polyoxymethylene from a melt-extrusion process:(II) Effects of thermal annealing and stretching on porosity. J Appl Polym Sci 84: 1762-1780
  18. Humbert S, Lame O, Séguéla R, Vigier G (2011) A re-examination of the elastic modulus dependence on crystallinity in semi-crystalline polymers. Polymer 52: 4899-4909
  19. Ding Z, Bao R, Zhao B, Yan J, Liu Z, Yang M (2013) Effects of annealing on structure and deformation mechanism of isotactic polypropylene film with row-nucleated lamellar structure. J Appl Polym Sci 130: 1659-1666
  20. Saffar A, Ajji A, Carreau PJ, Kamal MR (2014) The impact of new crystalline lamellae formation during annealing on the properties of polypropylene based films and membranes. Polymer 55: 3156-3167
  21. Bai H, Wang Y, Zhang Z, Han L, Li Y, Liu L, Zhou Z, Men Y (2009) Influence of annealing on microstructure and mechanical properties of isotactic polypropylene with β-phase nucleating agent. Macromolecules 42: 6647-6655
  22. Offord GT, Armstrong SR, Freeman BD, Baer E, Hiltner A, Swinnea JS, Paul DR (2013) Porosity enhancement in β nucleated isotactic polypropylene stretched films by thermal annealing. Polymer 54: 2577-2589
  23. Peacock A (2000). Handbook of polyethylene: Structures: Properties, and applications, Marcel Dekker, Inc.
  24. Kebritchi A, Nekoomansh M, Mohammadi F, Khonakdar HA (2014) The role of 1-hexene comonomer content in thermal behavior of medium density polyethylene (MDPE) synthesized using Phillips catalyst. Polyolefins J 1: 117-129
  25. Lee S-Y, Park S-Y, Song H-S (2006) Lamellar crystalline structure of hard elastic HDPE films and its influence on microporous membrane formation. Polymer 47: 3540-3547
  26. Chatterjee T, Patel R, Garnett J, Paradkar R, Ge S, Liu L, Forziati KT, Shah N (2014) Machine direction orientation of high density polyethylene (HDPE): Barrier and optical properties. Polymer 55: 4102-4115
  27. Siesler H (1984) Rheo-optical Fourier-Transform Infrared Spectroscopy (FTIRS) of polymers-6: Changes of crystal-axes orientation and state of order during uniaxial elongation of high-density polyethylene. Infrared Phys. 24: 239-244
  28. Siesler H (1984) Rheo-optical Fourier-Transform infrared spectroscopy: Vibrational spectra and mechanical properties of polymers. Adv Polym Sci 65: 1-77
  29. Tabatabaei SH, Carreau PJ, Ajji A (2008) Microporous membranes obtained from polypropylene blend films by stretching. J Membr Sci 325: 772-782
  30. Wunderlich B (1973) Macromolecular Physics, Volume 1: Crystal structure, morphology, defects, Academic Press.
  31. Schultz J, Hsiao BS, Samon J (2000) Structural development during the early stages of polymer melt spinning by in-situ synchrotron X-ray techniques. Polymer 41: 8887-8895
  32. Samon JM, Schultz JM, Hsiao BS (2002) Structure development in the early stages of crystallization during melt spinning. Polymer 43: 1873-1875