Eckardt Jonas, Moro Lorenzo, Colusso Elena, Šket Primož, Giovando Samuele, Tondi Gianluca
Department of Land, Environment, Agriculture and Forestry, University of Padua, Viale dell'Università 16, 35020 Padua, Italy.
Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padua, Italy.
Polymers (Basel). 2025 Jan 9;17(2):153. doi: 10.3390/polym17020153.
Tannin-based foams have gained attention as a potential bio-based alternative to conventional synthetic foams. Traditionally, namely condensed tannins (CT) have been used, leaving the potential of hydrolysable tannins (HT) largely unexplored. This study compared the performance of chestnut (HT) and quebracho (CT) in tannin-protein-based foams at different tannin ratios. Using soy protein isolate (SPI) and hexamine under acidic conditions, a series of tannin foams were produced through a mechanical foaming method and analyzed for cell structure, compression strength, thermal conductivity, and chemical stability. Results show that chestnut tannin is viable in hexamine SPI formulations but is harder to process due to lower reactivity, further resulting in higher material densities compared to quebracho. Foams with higher quebracho content featured smaller, more interconnected cells, while increasing chestnut content led to larger, less interconnected cells. Compression strength decreased with higher chestnut content, while fire resistance and thermal conductivity were influenced by material density rather than tannin type. The C-NMR analysis revealed covalent bonding of hexamine with both tannins, but potential covalent bonds with SPI were undetectable. Overall, chestnut tannin can substitute quebracho tannin in hexamine-SPI foams, though with compromises in terms of specific material properties and processability.
基于单宁的泡沫作为传统合成泡沫的一种潜在生物基替代品受到了关注。传统上，使用的是缩合单宁（CT），而可水解单宁（HT）的潜力在很大程度上未被探索。本研究比较了栗木单宁（HT）和坚木单宁（CT）在不同单宁比例下基于单宁 - 蛋白质的泡沫中的性能。在酸性条件下使用大豆分离蛋白（SPI）和六亚甲基四胺，通过机械发泡法制备了一系列单宁泡沫，并对其孔结构、抗压强度、热导率和化学稳定性进行了分析。结果表明，栗木单宁在六亚甲基四胺 - SPI配方中是可行的，但由于反应活性较低，加工难度较大，与坚木单宁相比，材料密度更高。坚木单宁含量较高的泡沫具有更小、相互连接更多的气孔，而栗木单宁含量增加则导致气孔更大、相互连接更少。抗压强度随着栗木单宁含量的增加而降低，而耐火性和热导率受材料密度而非单宁类型的影响。碳核磁共振分析表明六亚甲基四胺与两种单宁均形成了共价键，但未检测到与SPI的潜在共价键。总体而言，栗木单宁可以替代六亚甲基四胺 - SPI泡沫中的坚木单宁，尽管在特定材料性能和可加工性方面会有所妥协。
