Effect of buffers on gypsum particleboard properties

The paper recounts how buffers affect the physical and mechanical propertie s of gypsum particleboard (GPB) and the initial curing time (IC) of gypsum. The acidic buffers were better than alkaline buffers for prolonging the IC of gypsum and affecting the properties of GPB. Weak acids were advantageou s for curing gypsum. When suitable amounts of citric acid and trisodium. ci trate were added, high performances could be achieved and the IC of gypsum could be prolonged to about 2h. When alkaline buffers such as sodium carbon ate were added, the IC of gypsum was still short but the internal, bond str ength (IB), modulus of elasticity (MOE), and modulus of rupture (MOR) of GP B were obviously decreased. Citric acid was the best among the four buffers used; and the GPB had a good IB, MOE, MOR, and adequate IC when citric aci d of less than or equal to 0.1% was added. Sodium carbonate was not suitabl e owing to low performance and short IC. Gypsum curing is an endothermic re action.