Preparation of Melamine Urea Formaldehyde Organo Clay Nanocomposite Foams Using Thermal Processing and Microwave Irradiation Techniques and Investigation of Their Thermal Insulation and Compressive Strength

Abstract

Urea formaldehyde (UF), melamine formaldehyde (MF) and melamine urea formaldehyde (MUF) resins are the most common thermosetting resins. The most obvious advantage of MUF resin over urea formaldehyde resin is that it has much higher resistance to water. MUF resins, synthesized by condensing precursors such as melamine, urea and formaldehyde, have good flame-retardant properties as they release nitrogen gas when burning. Improving the mechanical, thermal and barrier properties of MF and MUF resins by adding various nanoparticles has become very interesting. One of the promising areas of use of MUF resin is their use as insulation foams. In particular, organo clay MUF nanocomposite foams have the potential to offer significant advantages such as improved mechanical and thermal properties as well as reduced water sensitivity. This study aims to prepare and characterize melamine urea formaldehyde organo-clay nanocomposite foams, as well as to examine their properties such as thermal insulation and compressive strength, by using the microwave irradiation technique together with thermal treatment, which can offer advantages such as high reaction rate, yield and purity, and short curing time. Characterization of virgin polymer and melamine formaldehyde organo clay nanocomposite foams prepared by in situ polymerization method, was made using XRD, FTIR, SEM, and HRTEM methods. Spectroscopic and microscopic analyzes showed that the organo-clay platelets exhibited an exfoliated distribution in the melamine-urea-formaldehyde polymer matrix, which did not change with increasing clay content. Although the highest compressive strength values were obtained in virgin MUF foam (0.44 MPa), the values, which partially decreased in nanocomposites, increased with increasing clay ratio and reached 0.38 MPa in the nanocomposite prepared with the highest clay ratio of 0.45 wt %. On the other hand, thermal conductivity coefficients decreased regularly with increasing clay content. Thus, it was concluded that the nanocomposite containing 0.45 organo clay by weight had optimal properties in terms of both strength and thermal insulation.