ABSTRACT

Long curing times of adhesives represent a decisive disadvantage in contrast to most mechanical joining techniques. In order to compensate for this disadvantage, current research concentrates on various methods for accelerating adhesive polymerisation e.g. UV, microwave or oven curing. In addition to aforementioned methods, heating by electromagnetic induction represents a promising solution to speed up the curing process of adhesively bonded components. When components are exposed to high-frequency (HF) electromagnetic fields (EMF), heat is generated by eddy current or hysteresis losses in materials sensitive to EMF. If non-metallic materials like glass or wood are to be joined, different types of inductively heatable susceptors, e.g. meshes, fibres or particles, are added to the adhesives in order to achieve heating and consequently faster monomer cross-linking. Particles made of Curie material (Curie particles, CP) represent a relatively new type of susceptors. Even if exposed to unregulated induction power, CP can only be heated up through induction up to their specific Curie temperature (T_c) above which no further CP-induced heating occurs. To guarantee an efficient and safe curing process, T_c may be adjusted to the curing temperature optimal compatible for the adhesive to be cured. Thus, an accelerated curing process is designed which eliminates the need to control arising adhesive temperatures by external temperate measurements and – at the same time – prevents the adhesive from overheating. The present paper represents the second part of a study investigating the influence resulting from CP-induced accelerated curing on mechanical and thermo-mechanical properties of a 2 K epoxy resin (2 K-EPX) and a 2 K polyurethane (2 K-PUR). While investigations in the first part concentrated on adhesive bulk properties, compound characteristics of the very same adhesives bonded on different substrate materials (aluminium, G-FRP and wood) were in the focus of the present paper. The authors showed with an experimental program of 256 single lap shear (SLS) specimens that compound characteristics of the two considered adhesives are fundamentally changed by application of the introduced curing process. In most cases, inductively cured SLS joints achieved higher or equivalent lap shear strengths compared to cold cured reference sets, with a reduction in curing time from 1 or 10 days down to 10 min.

摘要

与大多数机械连接技术相比，粘合剂的长固化时间是一个决定性的缺点。为了弥补这一缺点，目前的研究集中在加速粘合剂聚合的各种方法上，例如紫外线、微波或烘箱固化。除了上述方法之外，通过电磁感应加热是一种很有前途的解决方案，可以加快粘合组件的固化过程。当组件暴露在高频 (HF) 电磁场 (EMF) 中时，对 EMF 敏感的材料中的涡流或磁滞损耗会产生热量。如果要连接玻璃或木材等非金属材料，则需要使用不同类型的感应加热感受器，例如网格、纤维或颗粒，添加到粘合剂中以实现加热和因此更快的单体交联。由居里材料制成的粒子（居里粒子，CP）代表了一种相对较新的感受器。即使暴露在未调节的感应功率下，CP 也只能通过感应加热到其特定的居里温度（T _c ) 在此之上不再发生 CP 引起的加热。为了保证高效和安全的固化过程，T _c可以调节至与待固化粘合剂最佳相容的固化温度。因此，设计了一种加速固化工艺，无需通过外部温度测量来控制粘合剂温度升高，同时防止粘合剂过热。本文代表了一项研究的第二部分，该研究调查了 CP 诱导的加速固化对 2 K 环氧树脂 (2 K-EPX) 和 2 K 聚氨酯 (2 K-PUR) 的机械和热机械性能的影响. 虽然第一部分的研究集中在粘合剂的整体性能上，但在不同基材（铝、G-FRP 和木材）上粘合的相同粘合剂的复合特性是本文的重点。作者通过 256 个单搭接剪切 (SLS) 试样的实验程序表明，两种考虑的粘合剂的复合特性通过应用引入的固化过程而发生了根本性的变化。在大多数情况下，与冷固化参考组相比，感应固化 SLS 接头的搭接剪切强度更高或相当，固化时间从 1 天或 10 天减少到 10 分钟。