Journal of Polymer Research

, 23:16 | Cite as

Flow-induced β-crystal of iPP in microinjection molding: effects of addition of UHMWPE and the processing parameters

  • Qianying Chen
  • Zhang Xiang
  • Qi YangEmail author
  • Miqiu Kong
  • Yajiang Huang
  • Xia Liao
  • Yanhua Niu
  • Zhongguo Zhao
Original Paper


The flow-induced β-crystal of isotactic polypropylene (iPP) with addition of ultrahigh molecular weight polyethylene (UHMWPE) molded by microinjection and influences of processing parameters on the formation of β-crystal in iPP/UHMWPE microparts were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). It was found that the contents and the dispersion of UHMWE affect the formation of β-crystal in iPP/UHMWPE blend. With the addition of UHMWPE, Kβ values of the blends increased significantly compared with that of the pure iPP and reached the maximum at the content of 2 wt% UHMWPE. In addition, a better dispersion of UHMWPE can facilitate the formation of the β-crystal in the iPP/UHMWPE. The results showed that the thermal stability of the β-crystal was enhanced with increasing the mold temperature. When the mold temperature was increased from 60 to 120 °C, the β-crystal become more perfect. High injection speeds can promote the formation of the β-crystal, but the value of the injection speed must be within a certain range.


Isotactic polypropylene Ultrahigh molecular weight polyethylene Microinjection molding β-crystal Processing parameters 



This paper was financially supported by State Key Laboratory of Polymer Materials Engineering (Grant No.sklpme2014-2-08), the National Science of China (51121001), Sichuan Youth Science and Technology Foundation (2015JQ0012).


  1. 1.
    Ruprecht R, Gietzelt T, Müller K, Piotter V, Haußelt J (2002) Injection molding of microstructured components from plastics, metals and ceramics. Microsyst Technol 8:351–358CrossRefGoogle Scholar
  2. 2.
    Whiteside B, Martyn M, Coates P, Allan P, Hornsby P et al (2003) Micromoulding: process characteristics and product properties. Plast Rubber Compos 32:231–239CrossRefGoogle Scholar
  3. 3.
    Li L-P, Wei J-L, Yin B, Yang M-B (2012) Effects of spatial confinement and selective distribution of CB particles on the crystallization behavior of polypropylene. J Appl Polym Sci 123:3652–3661CrossRefGoogle Scholar
  4. 4.
    Zhang J, Guo C, Wu X, Liu F, Qian X (2011) Effects of processing parameters on flow-induced crystallization of iPP in microinjection molding. J Macromol Sci B 50:2227–2241CrossRefGoogle Scholar
  5. 5.
    Zhang K, Lu Z (2008) Analysis of morphology and performance of PP microstructures manufactured by micro injection molding. Microsyst Technol 14:209–214CrossRefGoogle Scholar
  6. 6.
    Jiang Z, Chen Y, Liu Z (2014) The morphology, crystallization and conductive performance of a polyoxymethylene/carbon nanotube nanocomposite prepared under microinjection molding conditions. J Polym Res 21Google Scholar
  7. 7.
    Yang C, Yin X-H, Cheng G-M (2013) Microinjection molding of microsystem components: new aspects in improving performance. J Micromech Microeng 23:093001CrossRefGoogle Scholar
  8. 8.
    Surace R, Trotta G, Bellantone V, Fassi I (2012) The micro injection moulding process for polymeric components manufacturing. New technologies—trends, innovations and research Intech Publishing, Manhattan: 65–90Google Scholar
  9. 9.
    Lin X, Caton-Rose F, Ren D, Wang K, Coates P (2013) Shear-induced crystallization morphology and mechanical property of high density polyethylene in micro-injection molding. J Polym Res 20Google Scholar
  10. 10.
    Su R, Zhang Z, Gao X, Ge Y, Wang K et al (2010) Polypropylene injection molded part with novel macroscopic bamboo-like bionic structure. J Phys Chem B 114:9994–10001CrossRefGoogle Scholar
  11. 11.
    Keller A, Kolnaar HW (1997) Flow‐induced orientation and structure formation. Materials Sci Tech-londGoogle Scholar
  12. 12.
    Hobbs J, Humphris A, Miles M (2001) In-situ atomic force microscopy of polyethylene crystallization. 1. crystallization from an oriented backbone. Macromolecules 34:5508–5519CrossRefGoogle Scholar
  13. 13.
    Hu W, Frenkel D, Mathot VB (2002) Simulation of shish-kebab crystallite induced by a single prealigned macromolecule. Macromolecules 35:7172–7174CrossRefGoogle Scholar
  14. 14.
    Varga J, Karger-Kocsis J (1996) Rules of supermolecular structure formation in sheared isotactic polypropylene melts. J Polym Sci Pol Phys 34:657–670CrossRefGoogle Scholar
  15. 15.
    Sun X, Li H, Lieberwirth I, Yan S (2007) α and β interfacial structures of the iPP/PET matrix/fiber systems. Macromolecules 40:8244–8249CrossRefGoogle Scholar
  16. 16.
    Varga J (2002) β-modification of isotactic polypropylene: preparation, structure, processing, properties, and application. J Macromol Sci B 41:1121–1171CrossRefGoogle Scholar
  17. 17.
    Varga J (1992) Supermolecular structure of isotactic polypropylene. J Mater Sci 27:2557–2579CrossRefGoogle Scholar
  18. 18.
    Varga J, Mudra I, Ehrenstein GW, Soc Plast E (1998) Morphology and properties of beta-nucleated injection molded isotactic polypropylene. 3492–3496Google Scholar
  19. 19.
    Sun X, Li H, Wang J, Yan S (2006) Shear-induced interfacial structure of isotactic polypropylene (iPP) in iPP/fiber composites. Macromolecules 39:8720–8726CrossRefGoogle Scholar
  20. 20.
    Zhang B, Chen J, Zhang X, Shen C (2011) Formation of β-cylindrites under supercooled extrusion of isotactic polypropylene at low shear stress. Polymer 52:2075–2084CrossRefGoogle Scholar
  21. 21.
    Fujiwara Y, Goto T, Yamashita Y (1987) Comparison of premelting and recrystallization behaviour of β-phase isotactic polypropylene by heating and cooling at different rates. Polymer 28:1253–1256CrossRefGoogle Scholar
  22. 22.
    Pawlak A, Piorkowska E (2001) Crystallization of isotactic polypropylene in a temperature gradient. Colloid Polym Sci 279:939–946CrossRefGoogle Scholar
  23. 23.
    Somani RH, Hsiao BS, Nogales A, Srinivas S, Tsou AH et al (2000) Structure development during shear flow-induced crystallization of i-PP: in-situ small-angle X-ray scattering study. Macromolecules 33:9385–9394CrossRefGoogle Scholar
  24. 24.
    Chen Y-H, Zhong G-J, Wang Y, Li Z-M, Li L (2009) Unusual tuning of mechanical properties of isotactic polypropylene using counteraction of shear flow and β-nucleating agent on β-form nucleation. Macromolecules 42:4343–4348CrossRefGoogle Scholar
  25. 25.
    Lu Z, Zhang K (2009) Crystal distribution and molecule orientation of micro injection molded polypropylene microstructured parts. Polym Eng Sci 49:1661–1665CrossRefGoogle Scholar
  26. 26.
    An Y, Gu L, Wang Y, Li Y-M, Yang W et al (2012) Morphologies of injection molded isotactic polypropylene/ultra high molecular weight polyethylene blends. Mater Des 35:633–639CrossRefGoogle Scholar
  27. 27.
    Avila-Orta CA, Burger C, Somani R, Yang L, Marom G et al (2005) Shear-induced crystallization of isotactic polypropylene within the oriented scaffold of noncrystalline ultrahigh molecular weight polyethylene. Polymer 46:8859–8871CrossRefGoogle Scholar
  28. 28.
    Nogales A, Hsiao BS, Somani RH, Srinivas S, Tsou AH et al (2001) Shear-induced crystallization of isotactic polypropylene with different molecular weight distributions: in situ small-and wide-angle X-ray scattering studies. Polymer 42:5247–5256CrossRefGoogle Scholar
  29. 29.
    An Y, Bao R-Y, Liu Z-Y, Wu X-J, Yang W et al (2013) Unusual hierarchical structures of mini-injection molded isotactic polypropylene/ultrahigh molecular weight polyethylene blends. Eur Polym J 49:538–548CrossRefGoogle Scholar
  30. 30.
    Li JX, Cheung WL, Jia D (1999) A study on the heat of fusion of β-polypropylene. Polymer 40:1219–1222CrossRefGoogle Scholar
  31. 31.
    Jones AT, Aizlewood JM, Beckett D (1964) Crystalline forms of isotactic polypropylene. Die Makromol Chemie 75:134–158CrossRefGoogle Scholar
  32. 32.
    Varga J (1995) Crystallization, melting and supermolecular structure of isotactic polypropylene. Polypropylene: Struct, Blends Compos 1:56–115Google Scholar
  33. 33.
    Tadmor Z (1974) Molecular orientation in injection molding. J Appl Polym Sci 18:1753–1772CrossRefGoogle Scholar
  34. 34.
    Yang C (2013) Flow-induced morphology evolution of uniformly miniaturized high-density polyethylene parts prepared by micro-injection molding. T Micromech Microeng 68:1745–1755Google Scholar
  35. 35.
    Des Cloizeaux J (1988) Double reptation vs. simple reptation in polymer melts. EPL (Europhysics Letters) 5: 437Google Scholar
  36. 36.
    Griffiths CA, Tosello G, Dimov SS, Scholz SG, Rees A, Whiteside B (2014) Characterisation of demoulding parameters in micro-injection moulding. Microsyst. Technol, 1–14Google Scholar
  37. 37.
    Yao DG (2011) Polymer micro-molding/forming processes. In: Koç M, Ozel T (eds) Micro-manufacturing: design and manufacturing of micro-products, 1st edn. Wiley, New Jersey, pp 197–233, Chapter 7 CrossRefGoogle Scholar
  38. 38.
    Frick A, Stern C, Michler G, Henning S, Ruff M (2010) Study on flow induced nano structures in iPP with different molecular weight and resulting strength behavior. Macromol Symp 91–101Google Scholar
  39. 39.
    Zhou QX, Liu FH, Guo C, Fu Q, Shen KZ, Zhang J (2011) Shish–kebab-like cylindrulite structures resulted from periodical shear-induced crystallization of isotactic polypropylene. Polymer 13:2970–2978CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Qianying Chen
    • 1
  • Zhang Xiang
    • 1
  • Qi Yang
    • 1
    Email author
  • Miqiu Kong
    • 1
  • Yajiang Huang
    • 1
  • Xia Liao
    • 1
  • Yanhua Niu
    • 1
  • Zhongguo Zhao
    • 1
  1. 1.College of Polymer Science and Engineering, the State Key Laboratory for Polymer Material EngineeringSichuan UniversityChengduPeople’s Republic of China

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