Hybrid Nylon-6/Silicon Nanocomposites with Improved Mechanical Properties

Abstract : The study involves the development of new strategies to form technically interesting hybrid nanocomposites with improved mechanical properties. In particular, a new 'dissolution' preparative route was developed which incorporates silica nanoparticles (<30 nm) into a nylon-6 matrix. The procedure relies on the judicious choice of organic solvent and pH control. The synthesis involves the dissolution of nylon-6 in formic acid followed by silica particle addition (as an acidified monodisperse sol) with stirring. Viscous solutions were prepared under cleanroom conditions and casted as thin films which are dried and vacuum treated at approx. 60 deg. C. TEM images revealed that the silica particles (i) retained their original shape and size (10-30 nm), (ii) are mono-dispersed and (iii) mainly non-agglomerated. The degree of crystallinity of the composites was determined with XRD as a function of percentage filler added. The nylon-6 phase is semi-crystalline while the silica phase is amorphous. Initial mechanical tests on the composites were conducted and showed with 1 wt% silica addition, the E modulus was increased to approx. 2600 MPa. The increase in mechanical properties may be a result of the nanosize filler particles which has good synergy with the nylon matrix. Friction and wear properties were also investigated on a pin on disk tribometer by running a flat pin of steel against the composite disc.