In my experience, there is not much difference in the foam morphology between, for example, 20 and 30 °C ambient temperature. A robust non-latent amine-catalyzed foam formulation simply speeds up slightly. The quality of the raw materials and the humidity are much more important, and the influence of additives like foam stabilizers or defoamers must not be underestimated. In the end, PU foam formulations can be quite complicated, so I fear there won't be a general answer.

In my experience, there is not much difference in the foam morphology between, for example, 20 and 30 °C ambient temperature. A robust non-latent amine-catalyzed foam formulation simply speeds up slightly. The quality of the raw materials and the humidity are much more important, and the influence of additives like foam stabilizers or defoamers must not be underestimated. In the end, PU foam formulations can be quite complicated, so I fear there won't be a general answer.

I agree with Stefan. The ambient temperature (in the 20-30 deg C range) has little, if any, influence on the formation and morphology of polyurethane foams, both flexible and rigid. Besides, the reaction is highly exothermic, so a considerable increase in temperature of the reaction mass is observed. The most important factors in the manufacture of PUF include chemical composition and functionality of polyols, catalysis, functional additives and processing conditions. However, the PUF morphology (cellular structure, density) is mainly affected by the type and amount of a surfactant used as well as processing parameters such as mixing intensity in case of a "pot" synthesis or mixing head pressure of a machine.

I am also working on PU nanocomposites. I agree with Pawel P. Sobecki. Regarding density variation the most important thing which i observed is mixing of the components A and B just before and after. If you did not shake components properly than you get a different density profile while before mixing if you shake properly with same rate and then mix components with same rate, you will get same density profile. Regarding temperature, if you search for temperature effect than you can understand the effect of temperature. I go through temperature effect study and found that a higher temperature increase the rate of curing. Now what can be the possible effect of fast curing is the question of interest for you? In my opinion, in a fast curing rate the probability of 100%mixing reduces which also leads air entrapment and effect density .On the other hand in a slow curing process the probability of mixing components is relatively high and consequently less chances of air entrapment.The mixing conditions have a great effects on morphology and structure....so inshort try to optimize you conditions, then you can see effects.I do hope, you can extract information which you required.

I worked previously at a company that manufactured PU foams for a variety of applications. As stated above, in general, the PU foam reaction is a complex, intricate interaction between a number of components. Very small changes in the quantity of some components, such as foaming modifiers and blowing agents, can easily result in over-or under blown foam. Even small disturbances of the reaction mixture during the creaming phase can have disastrous, non-reproducible effects. For best reproducibility, you need to have a formulation that has a large a window as possible for variability in the amount of each component. Even then, you must carefully and accurately weigh each component, and use the same batch size and same curing container for every experiment. for example, you can't simply use any vessel of a certain capacity. You must specify the dimensions of the vessel. If you take 2 500 mL containers, one that is very tall and narrow and the other dish-shaped, prepare a 100 mL batch and pour half into each vessel, your resulting products will have drastically different physical properties. This will be due mostly to the large differences in thermal transfer properties, but also partly due to the differences in the surface area that was in contact with the vessel walls. Also, don't overlook the effects that result from using raw materials that come form different production runs. Batch-to-batch variations in the raw material manufacture can change a terrific formulation into garbage.