Rolla, Missouri – The use of biopolyols in place of petroleum-based polyols in rigid foams can negatively affect the foam’s properties. A team at the Missouri University of Science and Technology has carried out a study into the role of additives in the properties of these foams in structural and thermal insulation applications.
In the study, which was partially funded by the Missouri Soybean Merchandising Council and the US Department of Agriculture, soy-based polyols were used to make rigid PU foams. Cell size, density, thermal resistivity and compression force deflection values were evaluated, and compared with Covestro’s petroleum-based foam Baydur 683.
The roles of catalyst, blowing agent, surfactants and different polyol functionalities were also assessed. In this case, they used dibutyltin dilaurate as the catalyst, and water as the blowing agent. Five different silicone-based surfactants were used to study how surface tension affected cell size in the foam.
They determined that 5g of surfactant per 100g polyol gave a foam with minimum surface tension, and the highest thermal resistivity, with an R value of 26.11m2K/W. Conversely, the CFD values were negatively impacted by higher surfactant loading.
In addition, blends with 5g of higher functionality soy-based polyol improved the CFD values to 328kPa. They said this was comparable to the figure for Baydur 683.
The work has been published in the Journal of Applied Polymer Science.