Formaldehyde Emission in Micron-Sized Wollastonite-Treated Plywood Bonded with Soy Flour and Urea-Formaldehyde Resin

Hamid R Taghiyari,Saman Ghahri,Seyed Behzad Hosseini,Mohammad Ghofrani,Antonios N Papadopoulos

doi:10.3390/app10196709

Abstract

Soy flour was partly substituted for urea-formaldehyde (UF) resin with different content to investigate its effect on formaldehyde emission in three-layer plywood panels. In each square meter of panels, 300 g of resin was used (wet weight basis of resin). Micron-sized wollastonite was added to the resin mixture at 5% and 10% consumption levels (wet weight basis of resin) to determine its potential effects as a reinforcing filler to mitigate the negative effects of addition of soy flour. Results showed a decreasing trend in formaldehyde emission as soy flour content increased to 20%. The highest shear-strength values were observed in panels with 10% and 15% soy flour content. The addition of wollastonite did not have a significant effect on formaldehyde emission, but it decreased the shear strength in soy-treated panels, although the values were still higher than those of control panels. Wollastonite significantly mitigated the negative effects of soy flour on the water absorption and thickness swelling of panels. It was concluded that 10% of soy flour and 5% of wollastonite provided the lowest formaldehyde emission and the most optimum physical and mechanical properties.

Highlights

Adhesives play an important role in the efficient utilization of wood resources and in the development and growth of the forest product industry
The decreasing effect of W on viscosity was attributed to the water content of the W gel that was added containing 10% soy flour and 5% wollastonite are recommended to achieve the optimum decrease to in the carcinogenic resin mixture.formaldehyde emission, as well as the optimum physical and mechanical properties
On the basis of the results of each property considered individually and altogether, it was concluded that panels containing 10% soy flour and 5% wollastonite are recommended to achieve the optimum decrease in carcinogenic formaldehyde emission, as well as the optimum physical and mechanical properties

Summary

Introduction

Adhesives play an important role in the efficient utilization of wood resources and in the development and growth of the forest product industry. The main classes of thermosetting adhesives are amino-based, phenolic, and isocyanate resins The utilization of these thermosetting adhesives is considered more economical, and reactive adhesives with quick curing behavior are versatile in a range of properties in the cured state. These adhesives have dominated the wood composite industry for many decades. Within this group, urea-formaldehyde (UF) resins are the most important adhesives in terms of quantity. Due to their low-cost raw materials, their rapid curing, their high dry-bond strength, and a colorless glue line, UF-based adhesives are almost exclusively used for producing wood-based materials, such as particleboard or medium-density fiberboards

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Results

Conclusion