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Formulating Tip: How to get consistent foam densities
Posted in: Formulating Tip of the Day by admin on October 29, 2010
Most if not all polyols and other raw materials contain background water. The blending process can also introduce water to your polyol side. You can either measure the background water before adding your blowing agent or just formulate with water as co-blowing agent so you can bring up the amount of water to a fixed level above the background level. Then you can always use a fixed amount for your non-water blowing agent. It is better to formulate using some water because it is low molecular weight and you need less of it. Thus, your index would be more consistent because the amount of water is figured into the index. If you choose to vary your amount of non-water blowing agent to compensate for the blow contribution of the background water, you will use larger amounts of blowing agent because it is higher molecular weight, which would lead to a larger fluctuation of the index in a system that is designed to be 1:1 ratio by volume.