Effects of casein on flammability and mechanical characteristics of medium density fibreboards based on formaldehyde-free resin system

Abstract

As one of the major milk proteins, casein has mainly been used in food and medical industries. Its applications have also been expanded to other areas, including its use as a textile fibre, coating material and as an adhesive. However, more recently, casein has shown great potential as an alternative flame retardant (FR) because it is non-toxic and biodegradable. Nevertheless, there are limited studies to investigate the effects of casein on flame retardant and mechanical properties of wood-based panels. In this research, we have set up a manufacturing process to fabricate fire resistant medium density fibreboards (MDFs). Casein is used as an FR compound to explore its effects on the fire and mechanical performance of wood-based MDF panels. Moreover, a soy flour-based resin system is selected as a replacement for the commonly used toxic formaldehyde-based resin. Two approaches are employed for the casein incorporation during the MDF manufacturing process: one is to spray casein solutions and another is to add pulverized casein particles. The spraying method with casein solution improves the flexure strength by approximately 48% compared to that of non-treated MDF samples, while the flexure strengths of MDF panels with ground casein particles dropped by nearly 26%. The addition of casein also reduced the heat release rate of the panel with a more compact char structure. The research clearly indicates the possibility of manufacturing fire-retardant casein-based MDF panels for their use in fire-prone areas.