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Effect of propylene glycol, rapeseed glycerine, and corn starch modified polyol blends parameters on the properties of thermal insulating polyurethane foams

Water-blown polyurethane foams have some drawbacks such as intensive shrinkage, relatively high density, skin peeling phenomena post blowing, and longer demold time. These drawbacks can be partially or fully eliminated by varying the characteristics of the main components. Therefore, aliphatic polyester rapeseed polyol produced via fermentation was mixed with common modifiers, such as propylene glycol, rapeseed glycerine, and corn starch. The impact of molecular weight and hydroxyl values of their mixtures was evaluated by testing the obtained bio-based polyurethane foams for reaction kinetics, some structural parameters, density, compressive strength, structure morphology, the change in thermal conductivity, dimensional stability, and long-term water absorption by total immersion. Keeping in mind the generation of carbon dioxide during foaming, it was interesting to study the change in the thermal conductivity after 1 day and 30 days after foam production. Propylene-glycol-modified foams had competing dimensional stability, reduced density, faster foam curing capability, lowest water absorption, and shortest demold time due to the obtained open cell structure. Rapeseed-glycerine-modified foams had better cross-linking capability, slower aging of thermal conductivity, and higher compressive strength. Corn starch-filled foams did not change the reaction start time, had lower density, better thermal conductivity, and higher closed cell content.