Thermal properties and flame retardancy of polyglycidyloxypropyl silsesquioxane/layered titanate nanocomposites

Abstract

Polyglycidyloxypropyl silsesquioxane, which has an excellent heat resistance, was combined with sheet-like and spherical titanate as nano-fillers. The burning property of the composites was related to the shape of the dispersed titanate. A burning test was carried out according to the UL-94 test method. As a result, though the test specimen burned from one end to the other in the spherical titanate filled composite system, a fire extinguishing property was observed in the sheet-like titanate filled composite system. The extinguishing time of the latter system classified V-0 in the specification test.

Flame retardancy and thermomechanical properties of the poly‐(glycidyloxypropyl) phenyl silsesquioxane/layered titanate nanocomposites

“…Moreover, the yield at 800°C in the PGPSQ system (39.0 wt %) was considerably higher than the theoretically calculated SiO 3/2 content (27.4 wt %). As mentioned in a previous paper,7 this result means that the PGPSQ prevents the epoxy matrix from thermal decomposition as well as the PGSQ system (the experimental yield at 800°C: 33.3 wt %, the theoretical yield: 23.6 wt %). In addition to this prevention, the introduced phenyl groups, which can easily form a noncombustible char, contribute to the high yield at 800°C.…”

“…On the other hand, the PGSQ showed the self‐extinguishing property for greater than a 5 wt % titanate content system. These results suggest that the sheet‐like structure of the organo‐layered titanate having a large scale surface area affects the self‐extinguishing property of the PGSQ system 7. Marvelously, self‐extinguishing of the PGPSQ system was achieved even in the 1 wt % titanate containing system and the system was classified UL V‐0.…”

“…They suggested that in the prevention of crack growth is based on the clay as a high aspect ratio filler. Layered titanate used in this study has a considerably high aspect ratio compared to ordinary clays 7. Therefore, there is high possibility of a ductility improvement of the silsesquioxane.…”

“…In a previous paper,7 we have already reported that the polyglycidyloxypropyl silsesquioxane (PGSQ) showed a high thermal stability and flame retardancy without harmful additives, because it contains an inorganic component in the backbone moiety. Moreover, the PGSQ, which was combined with an organo‐layered titanate, exhibited a self‐extinguishing property with a 5 wt % content of the organo‐layered titanate.…”

Thermomechanical Properties of Nanocomposites

“…Another interesting concept was developed by Harada and coworkers [20,21] , who studied the effect of a layered titanate fi ller on the fl ame retardancy and thermomechanical properties of a poly(glycidyloxypropyl) phenyl silsesquioxane ( PGPSQ ) matrix, and of poly(glycidyloxypropyl) silsesquioxane ( PGSQ ). Although PGSQ showed a high thermal stability and fl ame retardancy due to the presence of an inorganic component, when the formulation was loaded with 5% of an organolayered titanate it exhibited a self -extinguishing property.…”