Effect of Sizes of Nano Ca₃(PO₄)₂ on Mechanical and Thermal Properties of Polyurethane Foam Composites

Abstract

Particular sizes of nano inorganic filler, Ca₃(PO₄)₂ were prepared by following the matrix mediated growth technique. Composite foams were prepared on addition of different concentration (0.5–2.5 wt.%) of nano size filler in a single–phase polyurethane matrix. The differential Scanning Calorimetry (DSC) for composite as well as pure polyurethane was done to ascertain the degree of interaction of filler with the structure of the matrix as active sites. The degree of cell formation increases on increase in amount of reduced size nano filler in the composites where as decrease in case of larger size filler in composites. The increment in specific gravity from 0.17–0.25 for reduced nano size filler and 0.17–0.18 in case of larger size filler makes a strong support for the increment of cell numbers. The significant enhancement 250% in compressive strength, and the reduction of cell sizes shown in optical photographs satisfies the reasons of increment in heat of fusion (ΔH) in DSC. The decrement in (ΔH) cal/g in case of larger size filler for curing shows the conduction of heat is more due formation of cells less in numbers results in reduction of rate of heating more. Thermal gravimetric analysis (TGA) was done to know the degradation behavior. The TGA results, shows increment in onset temperature and mid temperature of the first step degradation in case of larger size nano filler. Decrement of flammability from 0.47–13.14 sec/mm for reduced nano size filler and 0.47–8.23 sec/mm in case of larger size filler, show that the incorporation of nano particles not only improves the mechanical properties but also retards the flammability.

Keywords:

• HIPS
• Nano Ca₃(PO₄)₂
• Nanocomposite
• Polyurethane

ACKNOWLEDGMENT

Authors are thankful to Department of Science and Technology (DST), New Delhi for providing financial assistance (Project No. SR/S-5/ WM-31/ 2003) to perform this research work.