Advertisement

Characterizations of Nanocomposites of Liquid Crystalline Polymers

Living reference work entry

Latest version View entry history

  • 88 Downloads
Part of the Polymers and Polymeric Composites: A Reference Series book series (POPOC)

Abstract

Nanocomposites of three thermotropic liquid crystalline polymers (TLCPs) with organoclay were prepared. The first TLCP, poly(2-ethoxyhydroquinone-2-bromoterephthaloyl), EHBT, consists of wholly aromatic ester type mesogenic units containing an ethoxy side group, and the second poly(oxybiphenyleneoxy-2,5-dihexyloxyterephthaloyl) (OBDT) is an aromatic polyester TLCP having alkoxy side groups on the terephthaloyl moiety. The last TLCP polyazomethine (PAM) consists of diad aromatic azomethine type mesogenic units. An EHBT with an alkoxy side-group was synthesized from 2-ethoxyhydroquinone and 2-bromoterephthalic acid. Nanocomposites of EHBT with Cloisite 25A (C25A) as an organoclay were prepared by the melting intercalation method above the melt temperature (Tm) of the TLCP. Liquid crystallinity, morphology, and thermo-mechanical behaviors were examined with increasing organoclay content from 0 to 6 wt%. Liquid crystallinity of the C25A/EHBT hybrids was observed when organoclay content was up to 6 wt%. Regardless of the clay content in the hybrids, the C25A in EHBT was highly dispersed in a nanometer scale. The hybrids (0–6 wt% C25A/EHBT) were processed for fiber spinning to examine their tensile properties. Ultimate strength and initial modulus of the EHBT hybrids increased with increasing clay content and the maximum values of the mechanical properties were obtained from the hybrid containing 6 wt% of the organoclay. A TLCP (OBDT)/organoclay nanocomposite was synthesized via in-situ intercalation polycondensation of diethyl-2,5-dihexyloxyterephthalic acid and 4,4′-biphenol in the presence of organically modified montmorillonite (MMT). The organoclay, C18–MMT, was prepared by the ion exchange of Na+–MMT with octadecylamine chloride (C18–Cl). OBDT/C18–MMT nanocomposites were prepared to examine the variations of the thermal properties, morphology, and liquid crystalline phases of the nanocomposites with clay content in the range 0–7 wt%. It was found that the addition of only a small amount of organoclay was sufficient to improve the thermal behavior of the OBDT hybrids, with maximum enhancement being observed at 1 wt% C18–MMT. Nanocomposites of PAM with the organoclay C12-MMT were also synthesized by using the in-situ interlayer polymerization method. The variations with organoclay content of the thermal properties, morphology, and liquid crystalline mesophases of the hybrids were determined for concentrations from 0 to 9 wt% C12-MMT. The wide-angle X-ray diffraction (XRD) analysis and transmission electron microscope (TEM) micrographs show that the levels of nanosize dispersion can be controlled by varying the C12-MMT content. The clay particles are better dispersed in the matrix polymer at low clay contents than at high clay contents. With the exception of the glass transition temperature (Tg), the maximum enhancement in the thermal properties was found to arise at an organoclay content of 1 wt%. Further, the PAM hybrids were shown to exhibit a nematic liquid crystalline phase for organoclay contents in the range 0–9 wt%.

Keywords

Thermotropic liquid crystalline polymers Nanocomposite Organoclay Montmorillonite Intercalation method 

Notes

Acknowledgments

This research was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Industrial Technology Innovation Program (No. 10063420, Development of high strengthen thermotropic liquid crystal polyester fiber).

References

  1. Agag T, Koga T, Takeichi T (2001) Stidies on thermal and mechanical properties of polyimide-clay nanocomposites. Polymer 42:3399–3408CrossRefGoogle Scholar
  2. Baird DG, Sun T (1990) Novel composites from blends of amorphous and semicrystalline engineering thermoplastics with liquid-crystalline polymers. In: Weiss RA and Ober CK (ed) Liquid crystalline polymers, 1st edn. ACS Symposium Series 435, Washington, p 416–438Google Scholar
  3. Chang J-H (2014) Preparation and characterization of poly(trimethylene terephthalate) nanocomposites. In: Pandey et al (eds) Handbook of polymer nanocomposites. Processing, performance and application, Volume a: layered silicates, 1st edn. Springer, New York, pp 267–292CrossRefGoogle Scholar
  4. Chang J-H, Jo B-W, Jin J-I (1994) In situ composites of a new thermotropic LCP and PBT. Korean Polym J 2:140–147Google Scholar
  5. Chang J-H, Ju CH, Kim SH (2006) Synthesis and characterization of a series of thermotropic liquid crystalline copolyester nanocomposites. J Polym Sci B Polym Phys 44:387–397CrossRefGoogle Scholar
  6. Chang J-H, Ham M, Kim J-C (2014) Comparison of properties of poly(vinyl alcohol) nanocomposites containing two different clays. J Nanosci Nanotechnol 14:8783–8791CrossRefGoogle Scholar
  7. Fornes TD, Yoon PJ, Hunter DL, Keskkula H, Paul DR (2002) Effect of organoclay structure on nylon 6 nanocomposite morphology and properties. Polymer 43:5915–5933CrossRefGoogle Scholar
  8. Garcia-Martinez JM, Laguna O, Areso S, Collar EP (2000) A thermal and mechanical study under dynamical conditions of polypropylene/mica composites containing atactic polypropylene with succinil-fluoresceine grafted groups as interfacial modifier from the matrix side. J Polym Sci B Polym Phys 38:1564–1574CrossRefGoogle Scholar
  9. Giannelis EP (1996) Polymer layered silicate nanocomposites. Adv Mater 8:29–35CrossRefGoogle Scholar
  10. Gilman JW (1999) Flammability and thermal stability studies of polymer layered-silicate (clay) nanocomposites. Appl Clay Sci 12:31–49CrossRefGoogle Scholar
  11. Ishida H, Campbell S, Blackwell J (2000) General approach to nanocomposite preparation. Chem Mater 12:1260–1267CrossRefGoogle Scholar
  12. Khonakdar HA, Jafari SH, Asadinezhad A (2008) A review on homopolymer, blends, and nanocomposites of poly(trimethylene terephthalate) as a new addition to the aromatic polyesters class. Iran Polym J 17:19–38Google Scholar
  13. Kojima Y, Usuki A, Kawasumi M, Okada A, Kurauchi T, Kamigaito O (1994) Fine structure of nylon-6-clay hybrid. J Polym Sci B Polym Phys 32:625–630CrossRefGoogle Scholar
  14. Lagaly G (1999) Introduction: from clay mineral-polymer interactions to clay mineral-polymer nanocomposites. Appl Clay Sci 15:1–9CrossRefGoogle Scholar
  15. LeBaron PC, Wang Z, Pinnavaia TJ (1999) Polymer-layered silicate nanocomposites: an overview. Appl Clay Sci 15:11–29CrossRefGoogle Scholar
  16. Lenz RW, Furukawa A, Bhowmik P, Garay RO, Majnusz J (1991) Synthesis and characterization of extended rod thermotropic polyesters with polyoxyethylene pendant substituents. Polymer 32:1703–1712CrossRefGoogle Scholar
  17. Lusignea RW (2001) LCP extrusion and applications. In: Chung TS (ed) Thermotropic liquid crystal polymers, 1st edn. Technomic Publishing, Lancaster, pp 303–350Google Scholar
  18. McArdle CB (1989) The application of side chain liquid crystal polymers in optical data storage. In: McArdle CB (ed) Side chain liquid crystal polymers, 1st edn. Blackie, New York, pp 357–394Google Scholar
  19. Min U, Chang J-H (2012) Colorless and transparent polyimide nanocomposite films: thermo-optical properties, morphology, and oxygen permeability. In: Panzini MI (ed) Thick films: properties, technology and applications, 1st edn. Nova Science, New York, pp 261–282Google Scholar
  20. Park D-K, Chang J-H (2000) Nanocomposites based on montmorillonite and thermotropic liquid crystalline polyester. Polymer (Korea) 24:399–406Google Scholar
  21. Shen Z, Simon GP, Cheng Y-B (2002) Comparison of solution intercalation and melt intercalation of polymer-clay nanocomposites. Polymer 43:4251–4260CrossRefGoogle Scholar
  22. Usuki A, Koiwai A, Kojima Y, Kawasumi M, Okada A, Kurauchi T, Kamigaito O (1995) Interaction of nylon 6-clay surface and mechanical properties of nylon 6-clay hybrid. J Appl Polym Sci 55:119–123CrossRefGoogle Scholar
  23. Vaia RA (2000) Structural characterization of polymer-layered silicate nanaocomposites. In: Pinnavaia TJ, Beal GW (eds) Polymer-clay nanocomposites, 1st edn. John Wiley & Sons, Chichester, pp 229–266Google Scholar
  24. Yang F, Qu Y, Yu Z (1998) Polyamide 6/silica nanocomposites prepared by in situ polymerization. J Appl Polym Sci 69:355–361CrossRefGoogle Scholar
  25. Yano K, Usuki A, Okada A (1997) Synthesis and properties of polyimide-clay hybrid films. J Polym Sci Part: A Polym Chem 35:2289–2294CrossRefGoogle Scholar

Authors and Affiliations

  1. 1.Department of Polymer Science and EngineeringKumoh National Institute of TechnologyGumiSouth Korea

Personalised recommendations