Sustainable particleboards with low formaldehyde emissions based on yeast protein extract adhesives Rhodotorula rubra

Abstract

Nowadays, there is great interest in developing adhesives that do not generate formaldehyde emissions. The objective of this work was to prepare adhesives based on yeast protein extract from Rhodotorula rubra (Rr) to make particleboards (PBs). The adhesives were characterized, and the physical and mechanical properties of the PBs were evaluated. The results were compared with those obtained using a commercial urea–formaldehyde adhesive (UF). Adhesives viscosity varied from 420 to 600 cP, with pH ranging from 4.35 to 4.73, and solid content of around 50%. The UF had a viscosity of 305 cP, pH of 7.53 and solid content of around 65%. Dynamic mechanical analysis showed that the wood-adhesive using protein extract Rr with reinforcing agent gave a good performance and stiffness, comparable to that using UF. The internal bond strength values of PBs varied from 0.36 to 0.46 N/mm2, while swelling thickness reached values of 24 and 38%, respectively. Density values of the PBs fluctuated between 682 and 693 Kg/m3. The formaldehyde emission of the PBs manufactured with Rr extract based adhesive had values between 0.2 and 0.3 mg/100 g, while formaldehyde emission for UF particleboard was 6.8 mg/100 g. Properties of the PB made of Rr based adhesives presented similar properties to particleboard manufactured with UF, but with lower level of formaldehyde emissions. The results from this research validate the manufacture of particleboards with Rhodotorula rubra yeast protein extract based adhesives. These PBs may have the same applications as the traditional PBs, with the advantage of being able to fulfill the high standards of formaldehyde emission demanded by the sustainable market.