Lionetto Francesca, Timo Alessia, Frigione Mariaenrica
Department of Engineering for Innovation, University of Salento, via per Monteroni, 73100 Lecce, Italy.
Blue Think S.p.A., Corso Vinzaglio 12, 10121 Torino, Italy.
Polymers (Basel). 2018 Dec 22;11(1):14. doi: 10.3390/polym11010014.
The development of improved cold-cured resins, to be used as either adhesives or matrices for FRP (fiber reinforced polymer) composites employed in the construction industry, has become the focus of several academic and industrial research projects. It is expected that the use of nano-structured organic⁻inorganic hybrid materials could represent a realistic alternative to commercial epoxy-based resins due to their superior properties, especially in terms of higher durability against: moisture, temperatures, harsh environments, and fire. In this context, organic⁻inorganic epoxy hybrids were synthesized by a modified sol⁻gel method without the addition of water. The experimental formulations were prepared starting from a mixture of a silane-functionalized epoxy resin, alkoxysilane components and a deep eutectic solvent (DES) based on a blend of choline chloride and urea. The latter was added in two different loads in order to analyze in depth its effect as a promoter for an effective dispersion of silica nano-phases, formed through hydrolysis and condensation reactions, into the cross-linked epoxy network. The produced formulations were cold-cured for different time spans in the presence of two hardeners, both suitable for a curing process at ambient temperature. In this first part of a wider experimental program, several analyses were carried out on the liquid (rheological and calorimetric) and cold-cured (calorimetric, thermogravimetric, dynamic-mechanical, flexural mechanical, and morphological) systems to evaluate and quantify the improvement in properties brought about by the presence of two different phases (organic and inorganic) in the same epoxy-based hybrid system.
开发性能更佳的冷固化树脂用作建筑行业中纤维增强聚合物（FRP）复合材料的粘合剂或基体，已成为多个学术和工业研究项目的重点。由于纳米结构有机-无机杂化材料具有卓越性能，特别是在防潮、耐温、适应恶劣环境和防火等方面具有更高的耐久性，预计其可成为商用环氧树脂的切实替代材料。在此背景下，通过改良的溶胶-凝胶法在不加水的情况下合成了有机-无机环氧杂化物。实验配方从硅烷官能化环氧树脂、烷氧基硅烷组分和基于氯化胆碱与尿素混合物的低共熔溶剂（DES）的混合物开始制备。后者以两种不同的用量添加，以便深入分析其作为促进剂的效果，该促进剂可使通过水解和缩合反应形成的二氧化硅纳米相有效分散到交联的环氧网络中。在两种适用于室温固化过程的固化剂存在下，对制备的配方进行不同时长的冷固化。在这个更广泛实验项目的第一部分中，对液体体系（流变学和量热学）和冷固化体系（量热学、热重分析、动态力学、弯曲力学和形态学）进行了多项分析，以评估和量化在同一环氧基杂化体系中两种不同相（有机相和无机相）的存在所带来的性能提升。
