Effect of bentonite on the structure and mechanical properties of CE/CTBN system

Cyanate ester (CE) resins are among the most important engineering thermosetting polymers and have received attention because of their outstanding physical properties. However, their main drawback is brittleness. Toughening by rubbers is a notable way to improve the toughness but unfortunately it decreases the modulus and thermostability. The CE/carboxyl terminal butadiene-acrylonitrile (CTBN)/bentonite (BT, a kind of clay) composites were prepared by two-step melt blending of CE, CTBN and amino-modified bentonite. The nanostructure and mechanical properties of the CE/ CTBN/BT composites were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and dynamic mechanical analysis (DMA). Both of the intercalated and exfoliated structures of BT existed in CE/CTBN/BT composites while rubber particles also could be observed in CE/CTBN/BT composites by TEM. When an appropriate amount (about 0.5 wt.%) of BT added into CE/CTBN (100/ 10 by weight) system, both of the modulus and impact strength increased. A 30% increase of the modulus was obtained without greatly sacrificing the impact strength of the composite when the BT content was 1 wt.%.