SIRRIS, Department of Innovations in Circular Economy and Renewable Materials, 3001 Leuven, Belgium.
Molecules. 2023 May 23;28(11):4259. doi: 10.3390/molecules28114259.
The phenalkamines (PK) derived from cardanol oil can be used as a bio-based crosslinker for epoxy coatings as an alternative for traditional fossil amines (FA). First, the reaction kinetics of an epoxy resin with four PK and FA crosslinkers are compared by differential scanning calorimetry, illustrating a fast reaction rate and higher conversion of PK at room temperature in parallel with a moderate exothermal reaction. Second, the performance of coatings with various concentrations of PK and PK/FA ratios indicates good mixing compatibility between crosslinkers resulting in higher hardness, scratch resistance, hydrophobicity, and abrasive wear resistance of coatings with PK. The superior performance is confirmed over a broad range of resin/crosslinker ratios, facilitating the processing with viscosity profiles depending on the PK type. Although fossil- and bio-based crosslinkers have different chemical structures, the unique linear relationships between intrinsic mechanical properties (i.e., ductility and impact resistance) and coating performance indicate that the degree of crosslinking is a primary parameter controlling coating performance, where PK simultaneously provides high hardness and ductility. In conclusion, the optimization of the processing range for bio-based PK as a crosslinker for epoxy coatings delivers suitable processing conditions and superior mechanical performance compared to traditional amine crosslinkers.
来源于腰果酚油的苯并恶嗪（PK）可用作环氧树脂的生物基型交联剂，以替代传统的化石基型胺（FA）。首先，通过差示扫描量热法比较了四种 PK 和 FA 交联剂与环氧树脂的反应动力学，结果表明 PK 在室温下具有更快的反应速率和更高的转化率，同时反应放热适中。其次，通过改变 PK 的浓度和 PK/FA 的比例制备了一系列涂层，结果表明交联剂之间具有良好的混合相容性，这使得 PK 基涂层具有更高的硬度、耐划伤性、疏水性和耐磨性。这种优异的性能在很宽的树脂/交联剂比例范围内得到了证实，有助于根据 PK 类型来调整涂层的粘度曲线。尽管化石基和生物基交联剂具有不同的化学结构，但内在机械性能（即延展性和抗冲击性）与涂层性能之间存在独特的线性关系，表明交联程度是控制涂层性能的主要参数，PK 同时提供了高硬度和高延展性。总之，优化了生物基 PK 作为环氧树脂交联剂的加工范围，与传统的胺交联剂相比，其具有合适的加工条件和卓越的机械性能。
