Preparation and characterization of Polyurethane foam with multi walled carbon nanotubes and Magnesium filler

Palm oil based polyol (POP) is gaining popularity to replace polyol based petroleum for manufacture of polyurethane (PU) foam due to the unique structure of oils, abundant, inexpensive and environmentally friendly. PU foam is a cellular structure that has several benefits, including low weight, high energy absorption capacity, and resistance to chemicals and solvents. However, PU foam have some drawbacks, including high porosity and high crushability porous that affects their mechanical properties. The addition of fillers has become a method of improving performance of PU foam. Therefore, the purpose of this research is to prepare and characterize a palm oil based PU foam with multi walled carbon nanotubes (MWCNTs) and magnesium (Mg) as fillers. The fillers were characterized by using pycnometer, scanning electron microscope (SEM), transmission electron microscope (TEM), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyzer (TGA). The PU foam composites (PU/MWCNTs, PU/Mg and PU/MWCNTs/Mg) were produced through the reaction of POP with methylene diphenyl diisocyanate (MDI) at a ratio of 1:1.1 by using high mechanical stirrer with 2000 rotations per minute (rpm). The PU foam composites were poured into a closed mould, cured for 24 hours and continued post cure in an oven at 80 °C for 2 hrs to confirm the reaction was completed. The effect of varying fillers content (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 %) on the PU/MWCNTs, PU/Mg, and PU/MWCNTs/Mg foam composites were determined using density, FTIR, thermal analysis, morphology, compression test, energy absorption and morphology analysis. The optimum compressive strength from PU/MWCNTs, PU/Mg and PU/MWCNTs/Mg foam composites were chosen and continued to investigate the displacement behaviour with finite element analysis (FEA) results by using ANSYS Multiphysics. The morphology of the foam structure was observed using the SEM and revealed the presence of a closed cell structure with a thinner cell wall. The addition of fillers has deteriorated the cell to broken cell. The nano size of MWCNTs was proven using the TEM and showed the addition of MWCNTs fillers at 0.5 % show the good MWCNTs dispersion in PU foam than 3.0 %. The increasing fillers content has improved the compressive strength by 1.547 MPa at 0.5 PU/MWCNTs, 1.688 MPa for 2.0 PU/Mg and 1.760 MPa for 2.5 PU/MWCNTs/Mg, respectively. Overall, 2.5 PU/MWCNTs/Mg showed the highest compressive strength due to the excellent combination of MWCNTs and Mg. Therefore, these PU foam composites were continued tested using ANSYS software. The theoretical results from FEA have shown small differences compared to the experimental results. The experimental result for 2.5 PU/MWCNTs/Mg foam composites was 1.76 MPa and the theoretical results obtained from ANSYS was 1.65 MPa. The differences between these were 0.11 MPa and have accepted because the gap is very small.