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Everwide Newsletter No.236


Experiment § Comparison of peel strength and shear strength

Friends who often read technical data must have a question, why is the peel strength of the adhesive always much lower than its shear strength? Let us illustrate with a simple experiment. Figure 1 is a typical peel strength test piece, A represents the part held by the gripper of the tensile machine, and B represents the position where the test piece is attached. Figures 2 to 4 show the test process. In this experiment, the maximum tensile force is 105kg divided by the width of the test piece 25.4mm, and the peel strength is 4kg/mm. Figure 5 is a typical shear strength test piece. In this experiment, the maximum tensile force is 1,800kg, divided by the cross-sectional area of the test piece 2.54 cm×2.54cm, and the shear strength is 250kg/cm2. At first glance, these two values are quite different. In fact, in the peeling mode, the external force is concentrated in a small area at the front end of the adhesive, and the adhesive area at the other back end is not stressed, so the peeling force is small. In contrast, all the adhesive areas in the shear mode can bear the external force together to a considerable extent, instead of being damaged in small pieces like the peeling mode, so the displayed strength is very large. In addition to this reason, it is also related to the force component during the test, but it is a bit complicated and will not be explained in this article.

—Author: Miss. Li-Ling, Liu

 

Activity § AED setting the place

AED (Automated External Defibrillator) is an automatic external cardiac defibrillator, also known as a fool defibrillator. The operator can use the voice instructions correctly. In view of the fact that the number of employees has exceeded one hundred, the government has also vigorously promoted the setting of AEDs. We cooperated with ZTE to set up AEDs in the Everwide Chemical Administration Building and specially arranged AED teaching courses so that the company’s colleagues could learn how to use them. In addition to explaining the operation steps of CPR and AED, the course also provided us with opportunities to practice. Everyone enthusiastically Q&A with the lecturer. I hope that this AED will be prepared and not used to prevent problems before they happen.

 

Knowledge § What environmental factors affect light-curing reaction is?

The light-curing reaction is affected by environmental factors. Taking cationic epoxy resin as an example, its reaction rate is easily affected by humidity, because moisture in the air will terminate the activity of cations and retard the reaction rate. Take the light-curable resin of the acrylic system as an example, the reaction rate is easily affected by oxygen in the air. Because light-cured acrylic resins are reacted by repeated steps such as the reaction of free radicals and monomers to generate new free radicals, but the free radicals will also react with oxygen in the air to produce peroxide with monomers. The reaction speed of the latter is hundreds of times faster than that of the former, and the reaction speed of the generated peroxide radicals with monomers is very slow, which affects the reaction speed. Different types of resins and different applications are affected differently, and the elimination strategies are different. For example, adhesive applications have no exposed parts and are relatively unaffected by the environment. In the application of paint and ink, the cationic system can be exposed in a low-humidity environment, and the acrylic system can be exposed in a nitrogen atmosphere, which can avoid the interference of environmental factors.

 

Living § Yunjia Wulian peak day tour

At dawn, I was looking forward to climbing a mountain with my colleagues for the first time. Today's goal is to climb the Five Peaks of Yunjia (a mountain extending from the edge of Yunlin County to Chiayi County), led by Yu ren senior. He said that this route is not very difficult, and you can go up the mountain with a jacket, snacks, and water. But it didn't take long for me to find out that "this trip is not easy at all." The path is sometimes flat and sometimes steep and winding. Although the signs remind us how many kilometers we have walked, it seems that we can never finish walking. The test of physical strength made me forget the uproar and distracting thoughts, only the peace of nature. Along the way, we saw large fields and hard-working tea farmers, unconsciously walked a long way and completed this first experience of climbing before dark. I think mountain climbing is a test. There is no option to give up. Once it starts, it must be completed. No matter how tired you go up the mountain, you still have to go down the mountain, and whenever you try to persevere, the scenery on the road will always make you forget the hard work. Encountering difficulties is like climbing a mountain. When we are at the bottom of the valley, looking up at the top of the mountain only feels far away, but if we can stick to the end and work hard to reach the top of the mountain, we will certainly be able to appreciate the different scenery, and no matter what the difficulty is, it will be solved. Thank you very much for the invitation to my colleagues. In the process of taking care of each other, they also taught me some knowledge and common sense and brought me to know the beauty of Taiwan. In this eight-hour journey, I have experienced the Yunjia Wulian Peaks. Maybe next time I can go to the next level and challenge a more difficult journey.

—Author: Mr. Zhi-Hung, Wei


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