The Effect of Mixing Pressure in a High-Pressure Machine on Morphological and Physical Properties of Free-Rising Rigid Polyurethane Foams—A Case Study

Abstract

This article presents the results of testing foam blocks made with a high-pressure foaming machine under industrial conditions. Foam blocks were made at pressures in the range of 110–170 bar with substrate temperatures allowed by machine suppliers. The foaming process parameters of each block were evaluated. The structure of the foams in the outer and central parts of the blocks was characterized using FTIR spectroscopic analysis and microscopic observations using SEM. The changes in apparent density, strength properties and brittleness of the foams were evaluated. The properties of the blocks made at different mixing pressures varied depending on the pressure at which the substrates were mixed and the location in the block. The biggest differences that were observed were the friability of the foams taken from different locations in the blocks by up to about 30%; the apparent density differed by about 8% and the compressive strength by about 5%.