NOVEL FUMED SILICA/SILICONE-UREA NANOCOMPOSITES: PREPARATION AND PROPERTIES

摘要

Novel fumed silica/silicone-urea nanocomposites were prepared and characterized. Silicone-urea copolymers were synthesized using polydimethylsiloxane (PDMS) oligomers with number average molecular weights of 3200, 10800 and 31500 g/mol. Two different types of silica, Wacker HDK H2000 (hydrophobic) and Wacker HDK N20 (hydrophilic) were utilized. Influence of silica type (hydrophilic versus hydrophobic) amount of silica loading and the PDMS soft segment molecular weight on the tensile properties and modulus-temperature behavior were determined. Major observations of this study were: (i) incorporation of silica does not seem to interfere with the hydrogen bonding between urea groups, (ii) incorporation of silica does not affect the glass transition temperature of PDMS, (iii) incorporation of silica significantly influences the tensile and thermomechanical properties of silicone-urea copolymers, (iv) average molecular weight of the PDMS soft segment in the silicone-urea copolymer seem to have significant effect on the tensile properties of the nanocomposites.