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

Abstract

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 kaolinfilled 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.