Nanomaterials to Improve the Strength of Wooden Joints

Nanomaterials have emerged as a promising and exhilarating class of materials that gained prominence in the advancement of technology due to their properties. It is in high demand for several practical applications, and one of them is in wood science, particularly as an adhesive used in wood composites and as an adhesive for wood joints in the preparation of furniture and structural components. Wood joints play a crucial role in keeping two pieces together to make more attractive elements, of greater strength and durability over time. Nanomaterials are known to enhance performance; thus, their application in wood joints. The present work represents a critical analysis of the application of nanomaterials in wood joint adhesives, considering their effects in the adhesion theories applicable to wood joints, the evaluation of the glue line in the wood joint, potential and applied tests for adhesives and wood joints and finally the stepladders needed to improve the applications of nanomaterials in a wood joint. Evaluation of available information showed that there are a wide variety of nanomaterials used as adhesives for wood joints, among them the most important are nanocellulose derivatives. Besides these, the most investigated adhesives are urea-formaldehyde, polyvinyl acetate, phenol-formaldehyde, polymeric diphenylmethane diisocyanate and epoxies. Of these, very limited studies have been conducted on urea melamine formaldehyde. As for the type of assessment, studies on analytical and chemical testing are predominant in the adhesives while evaluation of penetration of the nanomodified adhesive most often uses scanning electron microscopy (SEM). Mechanical testing for the wood joints is characterized by tension and shear strength but long term tests are lacking. Future efforts should focus on improving performance of nanomaterials for reinforcing wood joints. They should also should consider the effects of these nanomaterials on adhesion theories, which affect the common link established or presented in the glue line of wood joint. This would link of interphase subtract and adhesive and unadulterated wood link. There is an urgent need to expand the variety of adhesives for structural uses and to develop additional tests of wood joints, especially oriented toward long-term duration.