Uvida Mayara Carla, Almeida Adriana de Araújo, Pulcinelli Sandra Helena, Santilli Celso Valentim, Hammer Peter
Institute of Chemistry, São Paulo State University (UNESP), Araraquara 14800-060, Brazil.
Polymers (Basel). 2022 Aug 25;14(17):3474. doi: 10.3390/polym14173474.
Reinforcement steel extensively applied in civil construction is susceptible to corrosion due to the carbonation process in reinforced concrete and chloride ions diffusion. Epoxy-silica-based coatings are a promising option to guarantee the long-term stability of reinforced concrete structures. In this study, the influence of the proportion between the poly (bisphenol-A-co-epichlorhydrin) resin (DGEBA) and the curing agent diethylenetriamine (DETA) on the structural, morphological, and barrier properties of epoxy-silica nanocomposites were evaluated. To simulate different stages of concrete aging, electrochemical impedance spectroscopy (EIS) assays were performed for coated samples in a 3.5 wt.% NaCl solution (pH 7) and in simulated concrete pore solutions (SCPS), which represent the hydration environment in fresh concrete (SCPS2, pH 14) and after carbonation (SCPS1, pH 8). The results showed that coatings with an intermediate DETA to DGEBA ratio of 0.4, presented the best long-term corrosion protection with a low-frequency impedance modulus of up to 3.8 GΩ cm in NaCl and SCPS1 solutions. Small-angle X-ray scattering and atomic force microscopy analysis revealed that the best performance observed for the intermediate DETA proportion is associated with the presence of larger silica nanodomains, which act as a filler in the cross-linked epoxy matrix, thus favoring the formation of an efficient diffusion barrier.
广泛应用于民用建筑的钢筋，由于钢筋混凝土中的碳化过程和氯离子扩散，容易受到腐蚀。环氧 - 二氧化硅基涂层是保证钢筋混凝土结构长期稳定性的一个有前途的选择。在本研究中，评估了聚（双酚 - A - 共 - 环氧氯丙烷）树脂（DGEBA）与固化剂二亚乙基三胺（DETA）的比例对环氧 - 二氧化硅纳米复合材料的结构、形态和阻隔性能的影响。为了模拟混凝土老化的不同阶段，对涂覆样品在3.5 wt.% NaCl溶液（pH 7）和模拟混凝土孔隙溶液（SCPS）中进行了电化学阻抗谱（EIS）分析，SCPS代表新鲜混凝土（SCPS2，pH 14）和碳化后（SCPS1，pH 8）的水化环境。结果表明，DETA与DGEBA比例为0.4的中间比例涂层，在NaCl和SCPS1溶液中具有最佳的长期腐蚀防护性能，低频阻抗模量高达3.8 GΩ·cm。小角X射线散射和原子力显微镜分析表明，中间DETA比例观察到的最佳性能与较大的二氧化硅纳米域的存在有关，这些纳米域在交联的环氧基质中充当填料，从而有利于形成有效的扩散屏障。
