Study on the Fibre Reinforced Epoxy-based Intumescent Coating Formulations and their Char Characteristics

The paper presented the works on the effects of fibre reinforcement to the char characteristics of epoxy-based intumescent coating formulations. Reinforcing fibres such as glass fibre and carbon fibre that were manually cut to 10mm in length and chopped fibre strands 3mm length into formulations developed using commercial phosphate-based materials i.e. ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MEL) as the main ingredients. Five formulations; control (without fibre), glass fibre reinforced, carbon fibre reinforced, hybrid fibre (glass and carbon fibres) reinforced and chopped fibre reinforced were prepared. Powder formulations were grinded using Rocklabs grinder and epoxy-mixed using Caframo mixer, where the maximum speed used was 150rpm and later hand-applied onto primer coated carbon steel substrates at room temperature. Natural drying time at room temperature for the coatings to fully dry was determined. Thermogravimetric analysis (TGA) was conducted on epoxy, hardener and the mixes. Char formation and physical properties were investigated after the samples were exposed to high temperature fire tests up to 400ºC and 800ºC, respectively using electric furnace, Carbolite. Char height, weight, crispness, cell structure were examined and compared. Scanning electron microscopy (SEM) characterizations were also conducted to inspect fibre distribution and condition in the coatings as well as in the chars. The intumescent coatings prepared get fully dried in one to two days with the formulations having epoxy to hardener ratio of 2:1 demonstrated better fire performance char than 1:1 ratio. The results also showed long- carbon and glass fibres promote improved char’s cell structure, height and strength. Though both promotes more char and made the coatings experienced less weight loss, carbon fibre was more superior as it did not degrade.