UNMODIFIED LDH AS REINFORCING FILLER FOR XNBR AND THE DEVELOPMENT OF FLAME-RETARDANT ELASTOMER COMPOSITES

Layered double hydroxides (LDHs), inorganic clay materials with mixed metals present in the structure along with some interlayer cations, have immense potential for use as a filler in rubbers. We report the preparation and properties of a set of novel nano composites consisting of a LDH dispersed-in carboxylic-acrylonitrile-butadiene rubber (XNBR). We succeed in obtaining significantly improved physical properties by altering the chemical structure of a LDH with Zn and Al ions (Zn-Al LDH). In particular, we discover a significant reinforcing effect. This occurs despite the size difference between the LDH and traditional reinforcing fillers such as precipitated silica and carbon black. Both the elastic modulus and tensile strength increase. This increase is a function of the LDH concentration and, reaches a maximum value when the LDH concentration is at 100 phr. Experimental evidence suggests that this reinforcing effect is due to direct ion-to-ion interaction between the filler and the matrix. hi addition, we report that the presence of the nanofiller positively affects the flame retardence and thermal decomposition of the nanocomposites. We attribute this effect to the presence of a layer formed by the nanofiller.