Effects of CaCO3 and Kaolin Filler Loadings on Some Mechanical Properties of Poly Urethane Foams

In Nigeria, the foam industries basically use CaCO3 as filler in polyurethane (PU) foam manufacture. This has contributed to the high importation of this mineral, thereby, increasing dependency on imported goods. It is for this reason that, kaolin, a clay deposit commonly found on the upper Plateau in Central Nigeria is utilized as a potential filler in replacement or as a supplement for CaCO3.Various masses (0,2,4,6,8,10,12,14, and 16 g) of the fillers (CaCO3 or kaolin) were used in curing of PU foams and mechanical properties such as density, tensile strength, elongation at break, creep recovery and compression set were determined. Tensile strength values for CaCO3 and kaolin filled conventional polymer (CPO) are far higher than for CaCO3 and kaolin filled polymer polyol (PPO), generally. However, kaolin filled CPO foam display higher peaks at 2 g and 4 g compared to CaCO3 filled CPO within the same range. Similarly, CaCO3 filled CPO foams show higher peaks between 6 g and 12 g compared to kaolin filled CPO within the same concentration which seems to suggest that CaCO3 exhibits better filler acceptance (compatibility) at higher concentration to a limiting value. In the same vein, kaolin filled PPO foams exhibit tensile strength properties higher than CaCO3 filled PPO within the same concentration. Creep recovery for kaolin filled CPO are far higher than those of PPO, demonstrating that kaolin filled CPO exhibits far better % creep recovery property than CaCO3 filled CPO, PPO and kaolin filled PPO. Results for the effects of filler loading on compression tests display the same trend as % creep recoveries. Generally, incorporation of between 2 – 8% of Kaolin as filler improves tensile strength, creep recovery and compression set over and above CaCO3 even though it lowers the density of foams. Similarly, CaCO3 incorporation between 2 – 14% also improves the mechanical properties at lower values. Kaolin filled foams can be used for light weight application such as upholstery, packaging, industrial filters, etcetera.