A systematic study substituting polyether polyol with palm kernel oil based polyester polyol in rigid polyurethane foam

• We report the influence of systematic substitution with palm-kernel based polyol on the structure and properties of petroleum based rigid foam.
• Without any significant shrinkage, the foams were obtained with upto 50% palm kernel oil based polyols in the formulation.
• Based on improvement in mechanical properties and thermal resistance, the optimal concentration of palm kernel based polyol was found to be 20%.
• The improvement in properties upon palm-based polyol substitution is correlated to the associated morphological changes.

The future depletion of petroleum resources is driving development of sustainable alternatives based on biomaterials. This study is aimed at developing rigid polyurethane foam using high bio-based polyester polyol content without sacrificing the mechanical or thermal insulation performance associated with traditional polyether polyol based rigid polyurethane foam. In this paper, we quantify the properties of a model rigid polyurethane foam formulation based on a commercially available polyether polyol and then systematically substitute the polyether polyol with a commercially available palm kernel oil based polyester polyol. The influence of the palm kernel oil based polyester polyol content on reaction kinetics, structure, morphology and mechanical properties of rigid polyurethane foam were evaluated by cup test, Fourier transform infra-red spectroscopy, optical microscopy, and compression testing. Reaction rate was increased by the substation of polyether polyol with palm kernel based polyester polyol. Rigid polyurethane foams were successfully prepared by blending up to 50% of palm kernel oil based polyol with polyether polyol. Mechanical and thermal properties, as well as dimensional stability of rigid polyurethane foam with up to 30% palm kernel oil based polyester polyol gave comparable or better properties to the 100% polyether polyol based foams. Improved compressive strength without compromising thermal insulation was achieved at around 20% palm kernel oil based polyester polyol. This can be due to the formation of hard block segments of rigid urethane linkages composed of palm-based-polyols, into the discrete domains. In terms of the thermal conductivity, the improved thermal insulation properties were achieved at a composition of around 10% palm kernel oil based polyester polyol. Upon substitution of palm based polyols, while the onset degradation temperature was slightly reduced, stability (50% weight loss) above 350 °C was improved.

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