The Use of Solid State NMR to Characterize High Density Polyethylene/Organoclay Nanocomposites


Tathiane Rodrigues, Maria Tavares, Igor Soares, Ana Moreira and Antonio Ferreira

Recently the development of new materials, in special polymeric nanocomposites, formed by polymer and layered silicates, have gained attention. In this work nanocomposites based on high-density polyethylene matrix (HDPE) and organically modified clay were prepared by melt processing and characterized by the determination of proton spin-lattice relaxation time through solid state nuclear magnetic resonance (NMR) spectroscopy. This work has a proposal to add one quantitative technique to help the researchers to better evaluate polymeric nanocomposite, because NMR is an important tool employed to study both molecular structure and dynamic molecular behavior. The nanocomposites were mixed in a twin-screw extruder, varying the shear rate parameter: 60 and 90 rpm at 463 K. Nanocomposites obtained were characterized through X-ray diffraction; thermal analysis; impact resistance and nuclear magnetic resonance. The T1H results showed that the samples present different molecular domains according to the clay dispersion, forming an intercalated and/or exfoliated nanocomposites. The measurement of relaxation time, using low field NMR, is a useful method to evaluate changes in the molecular mobility of nanocomposite and can infer whether the sample is exfoliated and/or intercalated, since lamellar filler is used. 

[1] Rodrigues T., Tavares M. and Pita V.: Macromol. Symp., 2007, 245, 166. 
[2] Bikiaris D., Prinos J., Koutsoupoulos K. et al.: Polym. Degrad. Stab., 1998, 59, 287. 
[3] Rong M., Zhang M., Zheng Y. et al.: J. Mater. Sci. Lett., 2000, 19, 1159.
[4] Rong M., Zhang M., Zheng Y. et al.: Polym. Commun., 2001, 42, 3301.
[5] Rong M., Zhang M., Zheng Y. et al.: Polymer, 2001, 42, 167.
[6] Qin H., Zhao C., Zhang S. et al.: Polym. Degrad. Stab., 2003, 81, 497.
[7] Garces J., Moll D., Bicerano J. et al.: Adv. Mater., 2000, 12, 1835.
[8] Kurokawa Y., Yasuda H., Kashiwagi M. and Oya A.: J. Mater. Sci. Lett., 1997, 16, 1670.
[9] Kurokawa Y., Yasuda H. and Oya A.: J. Mater. Sci. Lett., 1996, 15, 1481.
[10] Bovey F. and Mirau P.: NMR of polymers. Academic Press, NY 1996.
[11] Komoroski R.: High resolution NMR spectroscopy of synthetic polymers in bulk. VCH Publishers, Deerfield Beach, Florida 1986.
[12] Sandres J. and Hunter B.: Modern NMR spectroscopy. A guide of chemists. 2nd edn., Oxford University Press, Oxford 1996.
[13] Callaghan P.: Principles of nuclear magnetic resonance microscopy. Oxford University Press, Inc., New York 1991.
[14] Vanderhart D., Asano A. and Gilman J.: Chem. of Mater., 2001, 13, 3796.
[15] Hotta S. and Paul D.: Polymer, 2004, 45, 7639.
[16] Osman M., Rupp J. and Suter U.: Polymer, 2005, 46, 8202.
[17] Alexandre M. and Dubois P.: Mater. Sci. Eng., 2000, 28, 1.
[18] Le Baron P., Wang Z. and Pinnavaia T.: Appl. Clay Sci., 1999, 15, 11.