In the trend of low-carbon and environmental protection, bio-based polyols are becoming more and more important, but their chemical structures are different from fossil-based polyols, and their performance when used to make polyurethane is different. A team from Zhejiang University has now published a systematic study investigating the effects of palm oil polyols on the microstructure and properties of flexible polyurethane foams.
They used varying levels of polyols to create foams and performed analytical studies including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy, dynamic thermomechanical analysis (DMA), thermogravimetric analysis and mechanical property testing.
The carbonyl groups in palm oil-derived polyols can form hydrogen bonds with the amino groups in the polyurethane hard segments. They believe this reduces the degree of microphase separation and increases the hydrogen bonding index from 67% to 89% as the biopolyol content increases.
Dynamic thermomechanical analysis (DMA) showed that the glass transition temperature increased with increasing bio-based polyol content. As the bio-based polyol content increases, the cell size decreases, the compressive strength of the foam also decreases, and the swelling ratio of the foam decreases.
They believe that the hydrogen bonds formed could provide opportunities for physical cross-linking and increase the strength of the foam.
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