Physical properties of medium-density wheat straw particleboard using different adhesives

Abstract

Wheat straw can be used as a fiber source for making particleboard. Straw particleboard has broad applications because of its rigidness, strength, and low cost. The objective of this research was to characterize the physical properties of medium-density wheat straw particleboard as affected by various types of adhesives, including methylene diphenyl diisocyanate (MDI), urea formaldehyde (UF), soybean protein isolate (SPI), and soybean flour (SF), as well as chemical treatment of the straw. Wheat straw particleboard was molded using a hot press. Mechanical properties, water absorption, thickness swell, and equilibrium moisture content were measured on the resulting particleboard. Among all adhesives, particleboard made from MDI showed superior mechanical performance and water resistance. Particleboard made from bleached straw had improved mechanical performance over that made from untreated straw. Soybean-based adhesives showed similar or better mechanical strength than UF resins for particleboard made from bleached straw, which indicated that soybean-based adhesives could be used to replace UF resin for indoor construction and furniture to avoid toxic emission from UF. Although the soybean-based adhesives had poorer mechanical properties than MDI resin, it is environmental friendly and could be used in applications with less stringent requirements for mechanical strength.