Iranian Polymer Journal ( IF 2.4 ) Pub Date : 2021-08-26 , DOI: 10.1007/s13726-021-00976-z Leonardo Dalseno Antonino 1 , Guilherme Elias Saltarelli Garcia 1 , Júlia Rocha Gouveia 1 , Demetrio Jackson dos Santos 1, 2 , Camila de Oliveira Viani 2 , Suel Eric Vidotti 2
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Epoxies offer many advantages in structural applications compared with other adhesives. However, their highly cross-linked structure leads to brittle materials, with low toughness and poor impact resistance. Usually, core–shell and reactive liquid rubbers are incorporated into industrial epoxy adhesives to overcome these limitations. Although important studies have been published in this field, it still lacks in the literature a comprehensive comparison between the effects of incorporating each type of rubber into the same epoxy matrix. Additionally, these reports usually focus on the behavior of the adhesive bulk, neglecting the effect of tougheners inclusion on the adhesively bonded joints fracture energy. Aiming to fill this gap, in this work, we prepared epoxy adhesives reinforced with core–shell rubber particles (CSR) or with a reactive liquid rubber (carboxyl-terminated polybutadiene-co-acrylonitrile—CTBN), at constant rubber contents in both formulations. Then, the toughened adhesives were investigated with respect to their thermomechanical behavior, as well as their adhesion performance. Bulk properties were characterized by uniaxial tensile tests and dynamic mechanical analysis, while the practical adhesion was investigated with single-lap shear and peeling tests. Finally, we assessed the adhesively bonded joints fracture energy in a customized experiment. The results showed that CTBN incorporation improved the adhesively bonded joints fracture energy by almost 816%, while CSR increased it by 550%. However, CTBN decreased the Tg of epoxy adhesives from 160 up to 130 °C, while CSR incorporation revealed no significant influence on Tg. Practical adhesion was increased by incorporation of both tougheners. In short, CTBN-containing samples revealed to be more efficient, even in smaller concentrations.
Graphic abstract
中文翻译：
核壳和反应性液体橡胶掺入对环氧粘合剂实际粘合力和断裂能的影响
与其他粘合剂相比，环氧树脂在结构应用中具有许多优势。然而，它们的高度交联结构导致材料脆，韧性低，抗冲击性差。通常，将核壳和反应性液体橡胶加入工业环氧树脂粘合剂中以克服这些限制。尽管该领域已经发表了重要的研究，但文献中仍然缺乏将每种类型的橡胶掺入相同环氧树脂基体的效果之间的综合比较。此外，这些报告通常集中在粘合剂本体的行为上，而忽略了增韧剂对粘合剂粘合接头断裂能的影响。旨在填补这一空白，在这项工作中，共丙烯腈-CTBN），两种配方中橡胶含量恒定。然后，研究了增韧粘合剂的热机械行为以及粘合性能。体积特性通过单轴拉伸试验和动态力学分析进行表征，而实际附着力通过单圈剪切和剥离试验进行研究。最后，我们在定制的实验中评估了粘合接头的断裂能。结果表明，CTBN 的加入使胶接接头的断裂能提高了近 816%，而 CSR 将其提高了 550%。然而，CTBN 将环氧粘合剂的T g从 160降低到 130 °C，而 CSR 掺入对T g没有显着影响. 两种增韧剂的结合增加了实际附着力。简而言之，即使在较小的浓度下，含有 CTBN 的样品也表现出更高的效率。
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