Epoxy composites with silicas

Ryszard Pilawka, Teofil Jesionowski 1 Politechnika Szczecińska, Instytut Polimerów, ul. Pułaskiego 10, 70-322 Szczecin, Poland 2 Politechnika Poznańska, Instytut Technologii i Inżynierii Chemicznej, pl. M. Skłodowskiej-Curie 2, 60-965 Poznań

Quarterly No. 4, 2008 pages 360-363

DOI:

keywords: epoxy resin, epoxy composites, silica fillers, tensile and bending strength

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abstract The epoxy compositions and composites hardened with 1-butylimidazole (1BI) with silicas have been investigated. Epoxy resin used was Epidian 6 (product of Chemical Works “Organika Sarzyna” in Nowa Sarzyna) and as fillers were applied silicas, products of precipitation reaction from solutions of sodium silicate and ammonium salts. The fillers were introduced to the compositions in amounts 1, 3 and 5 g per 100 g of the epoxy resin and the hardener was applied 1 g per 100 g of the resin. The time of dispergation of fillers was 20 minutes. Epoxy adhesives/composites were hardened in temperature 140°C for 4 hours. Modified silica’s were obtained from solution of sodium silicate and ammonium salts in precipitation method. As the precipitating agents NH4HCO3 (marked as: SiO2, SiO2-SH, SiO2-NH2) or ammonium chloride (SiO2-NH4Cl) were used. Modification of both types of silica’s fillers was conducted by adding appropriate silane coupling agents to the reactive mixture. The proadhesion compounds, applied at the amounts of 1, 3 or 5 weight parts per 100 weight parts of SiO2, were used to modify the precipitation system. Moreover, the particles size of the obtained powders using laser diffraction method (Mastersizer 2000, Malvern Instruments Ltd.) was determined. The investigations of viscosity of epoxy composition and curing process were carried out with the use the of rheometr ARES, Rheometric Scientific: the diameter of plates 25 mm, thickness between plates 1 mm. The glass temperature of composites (DMTA method) was measured with use of the apparatus Mark II, Polymer Laboratories, heat rate 3°C/min, frequency 1 Hz. The tensile and bending strengths were measured with standards PN-EN ISO 527-1 (speed rate 5 mm/min) and PN-EN ISO178 (speed rate 1 mm/min) with using of testing machine Instron 4026, Instron Corporation. The particle size remains in interval 12 do 30 μm for three kinds of silicas, whereas for silica with aminosilane in two ranges 36 and 3570 μm. The addition of 1 and 3 weight part of filler per 100 resin does not influence viscosities of epoxy composition. Introducing of silicas with amino or mercaptan groups accelerated of crosslinking process slightly. The epoxy composites with fillers have been comparable tensile and bending strength with unfilled systems. The introduction of silicas with amino or mercaptan groups increased inconsiderably the shear strength of epoxy composites. The glass temperature of epoxy composites is in the range between 106 and 135°C.