Abstract: This disclosure provides for new low density, open cell polyurethane (PUR) foams, which can be prepared using a combination of precursors and conditions, for example, an off-ratio A-side:B-side volume ratio (v:v) which includes a higher volume of A-side than the volume of B-side, an aromatic polyisocyanate component having an isocyanate functionality of from about 2.5 to about 3.0, and an Isocyanate Index of from about 20 percent to about 40 percent. Using the processes and precursors disclosed herein, polyurethane foams having a density of from about 0.25 lb/ft3 to about 0.45 lb/ft3 can be obtained.

Abstract: This disclosure provides for new polyisocyanurate (PIR) foams that exhibit improved flame retardant properties and thermal barrier properties, and which can pass certain thermal barrier tests in the absence of a protective covering such as specified in the thermal barriers codes. In an aspect, it has been unexpectedly discovered that when a relatively high viscosity and high functionality polyisocyanate is used with a high aromatic content polyester polyol and an HFO and/or HCFO blowing agent, and a flame retardant compound, unexpectedly good flame retardant polyisocyanurate foams can be generated, for example, when a high A-side:B-side volume ratio (v:v) and a relatively high Isocyanate Index (ISO Index) are used in the process.