جستجوی مقالات مرتبط با کلیدواژه « گچ میکرونیزه » در نشریات گروه « صنایع چوب و کاغذ »

In the present research improvement of dimensional stability and mechanical properties of gypsum particleboard by using white cement was investigated. In manufacturing gypsum particleboard, Micronize gypsum was used in three levels of 2.5:1, 2.75:1 and 3:1 to dried mass of wooden materials. White cement was added in 2 levels of 5 and 10% based on oven dried mass of gypsum to reinforce gypsum particleboard properties. Water absorption, thickness swelling after 2 and 24 hours immersion in water, bending strength, modulus of elasticity and internal bond strength were measured. Vicat needle method was used to investigate the effect of adding cement on setting time of gypsum. The results showed that adding 5% cement based on oven dried mass of gypsum, increased setting time and also mechanical properties. Adding cement over than 5% (10%), significantly improved dimensional stability but reduced setting time of gypsum and mechanical properties of the boards. On the other hand, results indicated that using Micronize gypsum to 2.75 times to dried mass of wooden materials, increased bending strength and modulus of elasticity. Increasing gypsum in to 3 times, reduced bending strength and modulus of elasticity, but improved internal bond strength and dimensional stability.

In this study in order to investigate the effect of gypsum type on the physical and mechanical properties of gypsum Particleboard were used from two type Jebel and Micronize gypsum. To obtain the suitable amount of gypsum in manufacturing gypsum particleboard was used from the three levels 2. 5:1، 2. 75:1 and 3:1 of gypsum to dried mass of wooden materials. Physical and mechanical properties of manufactured board were carried out in accordance with European Norms (EN) standard. The result showed that gypsum particleboard manufactured Jebel gypsum have the most mechanical properties (Bending strength، modulus of elasticity and internal bond strength)، but physical properties (water absorption and thickness swelling) of this boards was more than the boards manufactured from Micronize gypsum. Furthermore using 2. 75 times gypsum to dried mass of wooden materials is also suitable in production gypsum particleboard.