Rothenhäusler Florian, Ruckdaeschel Holger
Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
Neue Materialien Bayreuth GmbH, Gottlieb-Keim-Straße 60, 95448 Bayreuth, Germany.
Polymers (Basel). 2022 Oct 14;14(20):4331. doi: 10.3390/polym14204331.
The need for sustainable practices in the processing chain of fiber-reinforced thermosets has led to the development of bio-based epoxy resins and curing agents. As a contribution to sustainable composites, this study focuses on the glass transition temperature (Tg), viscosity and latency of diglycidyl ether of bisphenol a (DGEBA) cured with l-arginine in the presence of a urea-based accelerator. These characteristics are decisive features for application as a matrix in fiber-reinforced polymer composites produced via prepreg technology in which low viscosity and sufficient latency, meaning low reactivity of the one-component system, are necessary. The homogeneous mixture of amino acid and epoxy resin was prepared via three-roll milling. Two formulations, Argopox-1 with 1 wt.% accelerator and Argopox-2.5 with 2.5wt.% accelerator, were prepared and parts of each formulation were stored at 22 °C and -18 °C, respectively. Both formulations were tested via differential scanning calorimetry (DSC) and small amplitude oscillatory shear rheology (SAOS) after 0 d, 30 d, 60 d, 90 d and 180 d of storage to determine the influence of accelerator weight fraction, storage temperature and storage period on the glass transition temperature of the uncured resin system Tg0, and their viscosity. The Tg of the thermosets is about 100 °C. The DSC and SAOS measurements show that the Tg0 of Argopox-1 shifts about 5 °C in 60 d, while its viscosity is still low enough to be processed in a prepreg production line. Furthermore, Argopox-1 is storable for at least 180 d at -18 °C without significant changes in its Tg0 and viscosity. Consequently, Argopox-1 possesses a sufficiently high Tg and adequate latency, as well as a low viscosity for application as prepreg matrix material.
纤维增强热固性塑料加工链中对可持续实践的需求推动了生物基环氧树脂和固化剂的发展。作为对可持续复合材料的贡献，本研究聚焦于在基于尿素的促进剂存在下，用L-精氨酸固化的双酚A二缩水甘油醚（DGEBA）的玻璃化转变温度（Tg）、粘度和潜伏性。这些特性是作为通过预浸料技术生产的纤维增强聚合物复合材料中的基体应用的决定性特征，在该技术中，低粘度和足够的潜伏性（即单组分体系的低反应性）是必要的。氨基酸和环氧树脂的均匀混合物通过三辊研磨制备。制备了两种配方，含1 wt.%促进剂的Argopox-1和含2.5 wt.%促进剂的Argopox-2.5，每种配方的部分样品分别储存在22°C和-18°C下。在储存0天、30天、60天、90天和180天后，通过差示扫描量热法（DSC）和小振幅振荡剪切流变学（SAOS）对两种配方进行测试，以确定促进剂重量分数、储存温度和储存时间对未固化树脂体系的玻璃化转变温度Tg0及其粘度的影响。热固性塑料的Tg约为100°C。DSC和SAOS测量表明，Argopox-1的Tg0在60天内变化约5°C，而其粘度仍足够低，可在预浸料生产线中加工。此外，Argopox-1在-18°C下可储存至少180天，其Tg0和粘度无显著变化。因此，Argopox-1具有足够高的Tg和适当的潜伏性，以及低粘度，可作为预浸料基体材料应用。
