Liu Xiang, Fang Mei, Feng Yuezhan, Huang Ming, Liu Chuntai, Shen Changyu
State Key Laboratory of Structural Analysis, Optimization and CAE Software for Industrial Equipment, National Engineering Research Center for Advanced Polymer Processing Technology, Zhengzhou University, Zhengzhou, 450002, China.
Macromol Rapid Commun. 2024 Dec;45(23):e2400540. doi: 10.1002/marc.202400540. Epub 2024 Oct 7.
Diglycidyl ether of bisphenol A crosslinking with glutaric anhydride is used to form the conventional "covalent adaptive network", polyether sulfone (PES) by coiling and aggregating on the adaptive network is used to significantly increase the uncured resin viscosity for improving the processability of epoxy resin, but inevitably affecting the curing reaction and dynamic transesterification reaction. This study investigates the crucial roles of PES in curing dynamics and stress relaxation behavior. The results indicate that although PES does not directly participate in the crosslinking reaction of polyester-based epoxy vitrimers. Moreover, the isothermal curing studies reveal that the addition of PES can greatly bring forward the reaction rate peak from conversion α = 0.6 to α = 0.2, meaning that the curing mechanism transfers from chemical control to diffusion control. Dynamic property analysis shows that the addition of PES significantly accelerates stress relaxation, especially at lower temperatures, leading to low viscous flow activation energy E and relatively insensitive stress relaxation behavior to temperature. Introducing PES into vitrimer resin greatly improves crosslinking density (2.31 × 10⁴ mol m ), enhancing glass transition temperature (82.68 °C), tensile strength (68.66 MPa), and fracture toughness (6.25%). Additionally, the modified vitrimer resin exhibits satisfying shape memory performance and reprocessing capability.
双酚A二缩水甘油醚与戊二酸酐交联用于形成传统的“共价自适应网络”，聚醚砜（PES）通过在自适应网络上盘绕和聚集来显著提高未固化树脂的粘度，以改善环氧树脂的加工性能，但不可避免地会影响固化反应和动态酯交换反应。本研究探讨了PES在固化动力学和应力松弛行为中的关键作用。结果表明，尽管PES不直接参与聚酯基环氧类可塑弹性体的交联反应。此外，等温固化研究表明，PES的加入可将反应速率峰值从转化率α = 0.6时大幅提前至α = 0.2时，这意味着固化机理从化学控制转变为扩散控制。动态性能分析表明，PES的加入显著加速了应力松弛，尤其是在较低温度下，导致低粘性流动活化能E以及对应力松弛行为的温度相对不敏感。将PES引入可塑弹性体树脂中可大大提高交联密度（2.31×10⁴ mol m），提高玻璃化转变温度（82.68 °C）、拉伸强度（68.66 MPa）和断裂韧性（6.25%）。此外，改性可塑弹性体树脂表现出令人满意的形状记忆性能和再加工能力。
