Cardanol-based adhesive with reduced formaldehyde emission to produce particleboards with waste from bean crops.

Free formaldehyde is a carcinogen whose emission reduction in particleboard has been studied recently to mitigate this environmental and human health problem. One alternative to reduce the emission of formaldehyde in particleboards is by using adhesives produced from natural sources. Cardanol-formaldehyde is an environmentally friendly adhesive made with cashew nut liquid, a byproduct from the cashew chain. This work aimed to produce particleboard using cardanol-formaldehyde in place of urea. In addition, different proportions of bean straw wastes were used to replace pine wood. The combination of eco-friendly adhesive and lignocellulosic waste particles could result in a product that meets market demands while being environmentally nonaggressive. Cardanol-formaldehyde promoted a higher modulus of elasticity (MOE) (1172 MPa) and modulus of rupture (MOR) (4.39 MPa) about panels glued with urea-formaldehyde, which presented a MOE of 764 MPa and MOR of 2.45 MPa. Furthermore, the cardanol-formaldehyde adhesive promoted a 93% reduction in formaldehyde emission, with a reduction from 16.76 to 1.09 mg/100 g oven-dry board for particleboards produced with cardanol-formaldehyde, indicating potential as an adhesive in the particleboard industry.

Effect of surface treatment on the technological properties of coconut fiber-reinforced plant polyurethane composites.

Polymeric composites reinforced with plant fibers have numerous advantages, such as low cost, high raw material availability and good physical, mechanical and thermal properties. Thus, in recent years, they have been studied as thermal insulation substitutes for synthetic polymers in buildings. The aim of this study was to evaluate the technological properties of castor oil-based polyurethane composites reinforced with coconut fibers treated with hot water, alkaline solutions of NaOH and Ca(OH)2 and corona discharge and without surface treatment as materials for the thermal insulation of buildings. The composites were produced by the hand lay-up method followed by compression; 10% by weight coconut fibers were used to replace the synthetic polymer. Specimens were produced, and physical, mechanical, thermal and microstructural tests were performed. The results showed that the polymer had a thermal conductivity of 0.016 W/(mK), while the composites produced with fibers treated with NaOH had a thermal conductivity of 0.028 W/(mK); therefore, these polymers are considered insulating materials (k = 0.01 to 1.0 W/(mK)). Thus, the composites produced with coconut fibers can be considered as lighter, less expensive and environmentally friendly alternatives to synthetic polymers.