The effect of urea pretreatment on the formaldehyde emission and properties of straw particleboard

For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde （UF） resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the formaldehyde emission, physical and mechanical properties of the manufactured particleboard. Wheat straws were treated at three levels of urea concentration （5%, 10%, 15%） and 95℃ as holding temperature. Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive （UF-45, UF-91）. Then the formaldehyde emission values, physical properties and mechanical properties were considered. The results show that the for- maldehyde emission value was decreased by increasing urea concentration. Furthermore, the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens. Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.