几千年来，人类一直在自由地使用地球的自然资源. As the world stands today, however, 它面临着一个巨大的挑战，要从根本上改变做事的方式，以应对对更可持续的全球经济的迫切需求. 在各个行业，科学正在为一系列这样的变化铺平道路. At OU, Marco Gerini-Romagnoli, Ph.D., assistant professor of mechanical engineering (ME), 研究可脱粘和可逆的粘合剂，以方便零件更换, repair, and end-of-life (EoL) recycling.
In the case of many manufacturing industries, 本质变化的方向是使结构部件更轻, to move to fewer components, and to design for disassembly, 怎样才能促进EoL，并朝着循环经济的方向迈进.
“Strength, stiffness, 耐久性的提高以及设计灵活性的考虑使得粘合剂粘合在结构应用中越来越受欢迎. However, 对于复杂的多材料结构，粘结接头会阻碍修复或EoL回收活动, 或者至少使这个过程非常耗费人力和时间. 部件在拆卸过程中可能会损坏，或者分离EoL材料可能会有问题. De-bonding on demand technologies, theoretically, allow to overcome these limitations, but they are still largely in development,” explains Dr. Gerini-Romagnoli, 谁的重点是实现可逆粘合剂技术的结构复合材料接头.
诱导基材分离的方法之一是通过添加剂，添加剂可以在激活后削弱粘合层. 利用OU的紧固和连接研究所网站(FAJRI), 世界上为数不多的专门研究材料连接的学术研究机构之一, a collaborative group of researchers, which also includes Sayed Nassar, Ph.D. (ME), Roman Dembinski, Ph.D. (Department of Chemistry), and Dr. Gerini-Romagnoli’s student Khushboo Tedlapu, 开展了多项研究，以推进脱粘技术.
在最初的实验中，重点是具有至少一种金属衬底的接头. 将热膨胀颗粒(TEPs)添加到结构粘合剂中, Betamate 73326/73327M(两组分环氧树脂)，实现单搭接(SLJ)的可逆性. 该团队评估了环境老化对静态的影响, fatigue, and de-bonding performance of these SLJs. Specifically, 研究可逆性的参数是接头脱粘时间和脱粘过程中的基材温度.
研究表明，TEP添加剂的结合强度和脱键作用对环境老化不敏感.
“当添加剂浓度大于5% wt时，键的可逆性是可能的.随着颗粒含量的增加，脱键的时间和温度也随之减少. Gerini-Romagnoli.
该团队还致力于提高非金属连接基板的脱键性能, such as fiber reinforced composites. 在键合线上嵌入铁磁性嵌片可显著降低脱键时间和温度. The design of the inserts was optimized iteratively, 改进后的接头在搭接抗剪强度(比基线提高了10%)和TEP激活时间(缩短了两倍)方面同时得到改善。.
Currently, FAJRI小组正处于研究玻璃体的初期阶段，这是一种可以反交联的新型聚合物. In all traditional thermoset structural adhesives, 长聚合链在固化过程中发生交联, creating a strong 3-dimensional network. 交联提高了热固性胶粘剂的强度和玻璃化转变温度, often turning them from a paste into a solid. 然而，热固性聚合物中的交联键是不可逆的.
“在许多结构应用中，环氧基聚合物代表了可持续性和循环经济的一个有前途的选择. They are derived from thermoset polymers, 但它们的区别在于它们的可逆共价键. In practical terms, this means that a vitrimer-based adhesive can be reshaped, reformed, de-bonded, and reused, opening up exciting possibilities for recycling and repair, especially in defense, infrastructure, automotive, and aerospace industries,” says Khushboo Tedlapu, who is pursuing a master’s degree in mechanical engineering.
“今年已经发表了几项关于使用玻璃体作为粘合剂的早期研究, so we are not the first ones, but it's still a technology in its infancy. 期望是一旦我们将优化配方和应用, we will be able to re-bond de-bonded joints,” adds Dr. Gerini-Romagnoli.
Another aspect of Dr. 桂枝香的研究方向是复合胶合接头的无损检测(NDI), conducted along with Lianxiang Yang, Ph.D., distinguished professor of mechanical engineering. 由于复合材料基体中固有的材料不连续, NDI of bonded joints can be challenging. 科学家们正在研究光学技术与机械建模的协同集成，以检测粘合剂层中的空洞型缺陷.
无论采用何种连接方式，材料界面都是复杂而脆弱的区域. 开发一种可以按指令脱粘的可逆粘合剂是促进修复和可回收性的重要一步. Dr. Gerini-Romagnoli’s material joining research, which also involves bolted joints, 由NSF - IUCRC(产学研合作研究中心)支持的复合和杂化材料界面(CHMI), where he serves as an OU site manager. For more information, email [email protected].
December 20, 2023
By Arina Bokas
