The Effect of Nanoclay on Physical and Mechanical Properties of Particleboard Made from Urea-Kraft Lignin- Glyoxal Green Wood Adhesive

In this study a nontoxic aldehyde with high boiling point entitled glyoxal was used for reaction with urea and Kraft lignin to prepare green adhesive entitled urea- lignin- glyoxal (LUG). The prepared LUG resin had used in particleboard manufacturing. Then the influence of nanoclay addition on various properties of particleboard made from LUG resin was investigated. For this reason, the kraft lignin (10 wt%) was used instead of second urea in urea- glyoxal resin synthesis. After LUG resin synthesis in acidic condition and measuring physicochemical properties of the prepared resins, the prepared LUG resin was mixed with the 0.5, 1 and 1.5% nanoclay by mechanically stirring for 5 min at room temperature. Then the prepared resin was used in particleboard manufacturing. The physical properties of the prepared resins such as viscosity, gelation time, solid content and density as well as physical (water absorption) and mechanical (internal bond strength and flexural properties) properties of manufactured panels were measured according to standard methods. Also X-ray Diffractometry (XRD) was used to investigate the distribution of nanoclay on LUG resin. The physical test results indicated that gelation time of the LUG resin is slower than that of UF resin. Addition of nanocaly from 0.5 to 1.5% accelerates the gelation time of the prepared resins whereas the fastest gelation time related to the LUG resin containing 1.5% nanocaly. Also XRD analysis indicated that nanoclay could good separate when was mixed with LUG resin. Based on obtained result, the addition of nanoclay decreased the water absorption content of the manufactured panels, significantly. The internal bond strength and flexural strength of the panels was increased by addition the amount of nanoclay. Finally it must be noted that the addition of nanoclay had no significant effect on flexural modulus of the manufactured panels.