Thermal properties and flammability of acrylic nanocomposites based upon organophilic layered silicates

Thermal and mechanical properties of poly(methylmethacrylale-co-dodecylmeth acrylate) nanocomposites based upon exfoliated organophilic layered silicat es, were investigated as a function of the silicate and comonomer content. Layered silicates such as sodium bentonite were rendered organophilic by me ans of ion-exchanging sodium cations for N,N,N,N-dioctadecyl-dimethyl-ammon ium cations. Silicate exfoliation was enhanced by means of 5 and 10 wt.-% d odecyl-methacrylate (LMA) addition to afford translucent reinforced acrylic nanocomposites. In contrast to conventional filled acrylic polymers, only 10 wt.-% organophilic silicate was sufficient to increase Young's modulus f rom 2200 to 4030 MPa, glass temperature from 72 to 80 degrees C and degrada tion temperature from 220 to 256 degrees C with respect to the neat MMA/LMA (90 wt.-% /10 wt.%) copolymer. Flammability studies, performed on a cone c alorimeter, revealed that the maximum heat release rate of MMA/LMA copolyme r nanocomposite decreased from 837 kW/m(2) to 566 kW/m(2). The nanocomposit e morphology was examined by means of transmission electron microscopy (TEM ).