Property of nano-SiO2/urea formaldehyde resin

Abstract

In this paper, we discuss the effects of a nanometer silicon dioxide (nano-SiO 2 ) coupling agent, dispersal methods and the amount of nano-SiO 2 /urea formaldehyde resin. The results of our study indicate that when nano-SiO 2 , using KH-550 silane as a coupling agent, was added to UF resin by discontinuous ultrasonic vibration, its properties improved effectively. When the content of nano-SiO 2 was below 1.5%, the amount of free formaldehyde decreased, and the viscosity and bonding strength of resin increased with an increase in the added nano-SiO 2 , which did not prolong the curing time. The performance indices of plywood, particleboard and medium density fiberboard (MDF), hot-pressed by nano-SiO2 (1%)/UF resin (F/U molar ratio=1.2), exceeded the requirements of the National Standard. Their free formaldehyde emission reached E1 grade. Finally, we analyzed the mechanism of the strengthening effects of nano-SiO 2 on UF resin by means of infrared spectrum analysis and X-ray photoelectronic spectrum (XPS).Keywords nanometer silicon dioxide, urea formaldehyde (UF) resin, bonding strength, free formaldehyde, X-ray photoelectronic spectrum (XPS) 2 Materials and methods Experimental materialBoth urea and formaldehyde are commercial products. The content of nano-SiO 2 was 99%, the average diameter of particles 20 nm and the specific surface area 440 m 2 /g. There are four kinds of nano-SiO 2 : 1) NMSi-0, non-surfacing; 2) NMSi-A, using a 1% KH-550 silane coupling agent for treatment (molecular formula RESEARCH ARTICLE

Fumed silica as a filler for MUPF resin in the process of manufacturing water-resistant plywood

“…The obtained results correspond with those attained by other authors. Introducing small amounts of nano-SiO 2 into the UF resin reduced the formaldehyde release from particleboards, OSB, plywood and medium density fiberboards (MDF) glued with UF resin (Higuchi and Sakata 1981;Lin et al 2006;Roumeli et al 2012;Salari et al 2013). The literature review shows that the reduction of formaldehyde release from boards glued with UF resin modified by a small amount of nano-SiO 2 can be ascribed to absorption properties of the well-developed surface of silica (Leonovich et al 2002;Arafa et al 2004;Gun'ko et al 2005).…”

“…It is manifested by the increase in modulus of elasticity, modulus of rupture, internal bond, impact strength as well as thermal and chemical resistance. It is also commonly known that fumed silica enhances thermal, rheological and mechanical properties of various types of adhesives, such as thermoplastic polyurethane (Vega-Baudrit et al 2006), poly(vinyl acetate) (PVAc) (Bonnefond et al 2013), urea-formaldehyde (Leonovich et al 2002;Lin et al 2006;Roumeli et al 2012;Dukarska 2013) and starch-based wood adhesives (Wang et al 2011).…”

“…Researchers investigated mainly the possibility of using fumed silica and colloidal silica as an auxiliary agent in the process of producing particleboards glued with urea-formaldehyde resin. These research works determined the influence of silica on the structure of the cured UF resin and showed that the addition of silica into the resin results in the increase of its viscosity; yet, it does not significantly affect its cross-linking time or thermal stability and the produced boards have better physicomechanical properties (Leonovich et al 2002;Lin et al 2006;Roumeli et al 2012). Owing to the anti-sedimentation properties of nanoSiO 2 , it was possible to produce, by using phenolformaldehyde resin, water-resistant plywood of light-color adhesive bonds (Dukarska and Łęcka 2009).…”

The effect of organofunctional nanosilica on the cross-linking process and thermal resistance of UF resin

“…The paper by Dukarska and Czarnecki shows that small addition of nano-SiO 2 to MUPF resin makes it possible to optimize the process of plywood production by reducing the amount of resin mixture in the process of gluing the sheets of veneer [1]. According to Leonovich et al, Lin et al, Shi et al, Roumeli et al the introduction of nanosilica into urea-formaldehyde resin contributes to the growth of physico-mechanical properties of particleboards, MDF and wood [2][3][4][5]. Small amount of nano-SiO 2 added to UF resin improves the strength parameters of boards produced from rape straw particles [6,7].…”

“…The major criterion for the choice of proadhesive agent is the ability of its organofunctional group to create a chemical bond with a polymer. The most widely used modifiers of nanosilica surface are silane coupling agents: alkoxy-, chloro-, epoxy-and methacryloxy-functional with the general chemical formula (OR) 3 -SiO-X, where X means a functional group, e.g. amine group, bounded to a Si atom with an alkyl chain; OR means most frequently an alkoxy group which can be easily subjected to hydrolysis and shows chemical affinity to both the filler and polymer [11,12].…”