Effect of Technical Aerosil on the Properties of Adhesive Compositions

Abstract

The main drivers of competition among the products made with the use of adhesive compositions are the toxicity of finished products, the consumption of raw materials and energy resources, the duration of the main technological operations. These drivers can be controlled by using adhesives with different fillings and/or modifications. Adhesives based on phenol-formaldehyde and melamine-urea-formaldehyde resins are used to produce plywood with increased water resistance. Apart from resins, adhesives usually contain hardeners, fillers, and modifiers that affect the properties of the finished product. Technical aerosol is one of the modifiers of synthetic resins with a wide range of action. Aerosil is characterized by three types of interaction: physical adsorption, chemical adsorption (formation of hydrogen bridges by silanol groups), and chemical reactions on the surface layer. The chemical composition of aerosil was analyzed. Technical aluminum fluoride (AlF3) is of particular interest. It can interact with alkali metal fluorides with the formation of complex compounds that improve polymer structuring. The acids that make up aerosil reduce the pH to 2.0–3.5, so they can be catalysts for the curing process of melamine-urea-formaldehyde resins. The effect of technical aerosil on the properties of adhesive systems based on phenol-formaldehyde and melamine-ureaformaldehyde resins has been studied. Viscosity, curing time, and wetting ability of adhesive compositions were determined. The obtained results indicate the possibility of using this modifier in the composition of phenol-formaldehyde and melamine-urea-formaldehyde resins up to 15 pts. wt. The nature of the aerosil action on adhesive compositions was determined using IR spectroscopy. Analysis of the results showed that aerosil promotes deep structure formation of the polymer by increasing the molecular weight of the molecules. These bonds make it possible to form a more structured polymer with bound formaldehyde. Studies of the effect of aerosil on the properties of finished products were carried out. At the same time, an increase in performance indicators was found: the strength of adhesion increases, the toxicity of plywood decreases. The results of experiments on the effect of technical aerosil, taking into account the reduction of bonding time can be applied in the development of technological processes for obtaining plywood of high water resistance. For citation: Sokolova E.G., Rusakov D.S., Varankina G.S., Chubinsky A.N. Effect of Technical Aerosil on the Properties of Adhesive Compositions. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 133–144. DOI: 10.37482/0536-1036-2021-3-133-144