Reinforcement of polyurethane composites with an organically
modified montmorillonite
Jiawen Xiong, Zhen Zheng, Hongmei Jiang, Sufang Ye, Xinling Wang
*
Department of Polymer Science and Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, PR China
Received 9 September 2005; received in revised form 9 January 2006; accepted 9 January 2006
Abstract
A clay with reactive activity prepared by treatment of natural montmorillonite with Methylene-bis-ortho-chloroaniline (MOCA) was
incorporated into polyurethane matrix and a series of PU/clay nanocomposites were obtained by in situ polymerization. The microstruc-
ture of the nanocomposites with different content of the clay was examined by atomic force microscopy (AFM). The thermal and
mechanical properties of the nanocomposites with different organic clay content were characterized by dynamic mechanical thermal anal-
ysis (DMTA) and thermogravimetric analysis (TGA). It was found that the moduli and thermal stability of the nanocomposites were
improved with augment of clay, especially, for the PU/9 wt% MO-MMT nanocomposite, compared to pure PU, the storage modulus
and the loss modulus were increased by about 300% and 667% at À45 °C, respectively.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: A. Polymer–matrix composites (PMCs); B. Microstructure; B. Mechanical properties; E. Compression moulding
1. Introduction
Since Usuki and coworkers first reported the superior
nylon 6 montmorillonite (MMT) nanocomposite [1,2],
polymer-layered silicate nanocomposites have attracted
great interest from researchers due to their academic and
industrial importance [3,4]. MMT, a layered silicate used
widely to prepare polymer–clay nanocomposites, consists
of two external silica tetrahedral sheets and a central octa-
hedral sheet of alumina. The layers with high aspect ratio
(about 1 nm thickness and 100 nm width and length) are
stacked via weak dipolar force and form interlayer galleries
which are generally occupied by cations (for example Na
+
,
Ca
2+
,Li
+
) which can be easily substituted with organic
cations via ion exchange reaction in water. The special
structures of MMT play important roles in improving
mechanical, thermal and diffuse barrier properties of
polymer-layered silicate nanocomposites [5–7].Upto
now, many polymer matrices have been used to prepare
polymer–MMT nanocomposites (such as polyimide, polyc-
aprolactone, polypropylene, polyaniline and polyurethane)
[8–12]. The studies show that some properties of the nano-
composites are significantly improved by incorporation of
MMT into polymer matrices.
Due to the poor compatibility of MMT with organic
monomers and polymer matrices, it is necessary to modify
MMT in the preparation of polymer–MMT nanocompos-
ites for high performance. An effective way to modify the
nature of MMT is to substitute the cations in the interlayer
galleries of layers with cationic-organic surfactants. On one
hand, organic modifiers can impart hydrophilicity to the
MMT, which can improve the compatibility of MMT with
polymers. On the other hand, the gallery spacing of the
modified MMT becomes larger than that of MMT. Organ-
ically modified clays plays an important role in the forma-
tion of the structure and morphology of polymer/clay
nanocomposites, and thus significantly influences material
properties. Therefore, the choice of modifiers used to treat
clay is crucial to prepare polymer/clay nanocomposites
1359-835X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.compositesa.2006.01.014
*
Corresponding author. Tel.: +86 21 54745817; fax: +86 21 54741297.
E-mail address: xlwang@sjtu.edu.cn (X. Wang).
www.elsevier.com/locate/compositesa
Composites: Part A 38 (2007) 132–137