There were no appreciable differences in these characteristics between the two formulations. Both foams displayed similar core density, closed cell content and compression strength.
The percentage of closed cells in a rigid foam influences the thermal insulation capacity of the foam. In both systems, more than 90% of the cells were closed. The heat transfer value of the foams is also shown in Table 2, and expressed by the Lambda values. As expected, the low results for both foams is very good. The tests show that these polyol samples reacted in a very similar manner, with both producing good quality, closed-celled foams with acceptable lambda values.
As well as carrying out tests on these formulations, we also reviewed some of the blowing agents, catalysts, fire retardant and other additives that are commonly used in rigid polyurethane formulations. This review suggests that there are no issues from a compatibility perspective. However, there are some slight question marks over some of polyester polyols.
As with their petrochemical forerunners, the tertiary amine generated when manufacturing the Mannich polyols from refined CNSL conveys some auto-catalytic acceleration that can reduce the level of acceleration that may be needed in the formulation.
Mannich-base phenolic polyols can increase in viscosity and molecular weight over time especially after prolonged storage at high temperatures. There are no appreciable differences in viscosity or chain extension observed between the standard petrochemical grade and the new bio-based grade. The BDP 4133 contains 67% carbon derived from renewable sources, compared with 0% for petrochemically derived Curaphen 20-211.
The new series of Cardamine bio-based phenolic polyols are derived from sustainable feedstocks, and offer an excellent alternative to conventional petrochemical-based Mannich base polyols for rigid polyurethane systems. They are compliant with Reach and other regulatory requirements, and may be used in standard formulations that can be readily adjusted to match to any target requirements.
With comparable cell structure, comparable density, and good insulation properties, we believe these bio-based products are a suitable alternative to current industry-standard materials. Additionally, it is possible to alter the functionality and aromaticity of these bio-based products to meet market demands. The bio-based grades offer comparable performance to the established petrochemical grades.
Paul H Jones FRSC is the owner and managing director of Bitrez and Anacarda. Paul has been responsible for the development of new products that have been recognise with two separate Queen’s Awards for Enterprise for innovation, and an IChemE global award. He is also 2021 Chemistry World Entrepreneur of the Year.
I would like to express special thanks to Dr Barrie Colvin for providing the independent screening and analysis of the conventional and bio-based system foams.