Publications

Rheological and Mechanical Property Measurements of PMDI Foam at Elevated Temperatures

Nemer, Martin N.; Brooks, Carlton F.; Shelden, Bion S.; Soehnel, Melissa M.; Barringer, David A.

A study was undertaken to determine the viscosity of liquefied 20 lb/ft³ poly methylene diisocyanate (PMDI) foam and the stress required to puncture solid PMDI foam at elevated temperatures. For the rheological measurements the foam was a priori liquefied in a pressure vessel such that the volatiles were not lost in the liquefaction process. The viscosity of the liquefied PMDI foam was found to be Newtonian with a power law dependence on temperature log₁₀(μ/Pa s) = 20.6 – 9.5 log₁₀(T/°C) for temperatures below 170 °C. Above 170 °C, the viscosity was in the range of 0.3 Pa s which is close to the lower measurement limit (≈ 0.1 Pa s) of the pressurized rheometer. The mechanical pressure required to break through 20lb/ft³ foam was 500-800 psi at temperatures from room temperature up to 180 °C. The mechanical pressure required to break through 10 lb/ft³ was 170-300 psi at temperatures from room temperature up to 180 °C. We have not been able to cause gas to break through the 20 lb/ft³ PMDI foam at gas pressures up to 100 psi.