Investigation of Texture, Thermal Conduction and Some Mechanical Properties of Melamine Formaldehyde Foam and Melamine Formaldehyde-Organo-Clay Nanocomposite and Some Hybrid Composites

Abstract

Generally, mineral fillers are added to thermoplastic polymers to reduce cost and improve performance. However, properly selected mineral fillers can also improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability, and molding cycle time in thermoset polymers. This study focused on the preparation and microscopic and spectroscopic characterization of various hybrid composites using pumice as primary filler and gypsum, kaolin and hollow glass sphere as secondary fillers, as well as examining some of their mechanical properties and thermal conductivities. For this, first of all, surface modification of the clay was carried out by intercalation method from solution using raw Montmorillonite, cationic surfactant and long chain hydrocarbon material, and then organo-clay melamine formaldehyde nanocomposite was prepared by in situ synthesis using organo clay and melamine formaldehyde pre-polymer. Finally, non-ionic surfactant, foaming agent and glycerin were added to the prepared nano-composite at approximately 90°C, mixed mechanically and then pumice was added. The processes at this stage were repeated while preparing hybrid composites with pumice and other mineral additives. For curing and molding, the composite was first subjected to microwave irradiation for 5 minutes followed by thermal treatment at 140°C for 60 min. Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) spectra and Scanning electron microscope (SEM) and High resolution transmission electron microscope (HRTEM) images were taken for morphological and textural characterization for raw clay (MMT), organo clay (OMMT) and pure polymer with prepared hybrid composites. In addition, some mechanical properties such as bending strength, elasticity modulus and screw holding resistance, as well as thermal conductivity coefficients of the hybrid composites were determined according to the relevant standards and the obtained results were evaluated. Spectroscopic and microscopic analyzes have shown that effective adhesion interactions occur between polymer-clay nanocomposite particles and filler grains, thus resulting in textural arrangements with different properties. Mechanical and thermal conductivity test results showed that melamine formaldehyde-organo-clay nano composite foam and hybrid composite containing hollow glass sphere are highly qualified materials in terms of thermal insulation and mechanical strength.