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Everwide Newsletter No.253


Experiment § Different forms of structural adhesive-sheet adhesive

Sheet adhesive is composed of resin and fiber, like a film-like adhesive (Biweekly Report No. 88). There are several factors to consider when designing a good sheet adhesive. First of all, considering the interface problem, the wetting of the resin of the sheet adhesive to the substrate is the first requirement. Only with a good wetting effect can the resin penetrate into the pores of the substrate and hold the substrate firmly. Figure 1 shows the poor wetting effect. It can be seen that the resin does not completely wet the substrate, and the adhesive surface is quite shiny (the part circled in red). Adhesion failure not only occurs between the glue and the substrate but also between the glue and the fiber. Figure 2 shows the adhesion failure of the resin and fiber. The fiber surface is completely smooth (pointed by the red arrow). Cohesion failure, simply means that the glue is not strong enough, the cohesive force of the glue cannot withstand the external force, the internal structure of the glue begins to collapse, so the glue will evenly remain on the two substrates that are connected (Figure 3). Taking the above points into consideration, we developed an adhesive sheet adhesive NC450-18, which is flexible in operation (Figure 4) and ductility (Figure 5), allowing users to easily process it. NC450-18 also has a high shear strength of 380 Kgf/cm2 and superior mechanical properties.

—Author: Mr. Rong-Xin, Lin

 

Activity § Factory renovation: erecting canopies

We will carry out factory renovation every year and hope to let everyone work in a more comfortable environment. In recent years, sudden heavy rains often sprayed rainwater into the factory building, causing water to accumulate on the floor, which made colleagues very inconvenient. Therefore, we first built two large canopies to see if we could solve the troubles caused by heavy wind and heavy rain. Different from the common canvas canopy, our canopy is made of an iron frame to prevent it from being blown off by strong winds. In order to maintain good lighting, we use matte tempered glass. All the projects were completed smoothly before the typhoon season. How effective is it? You will know when the rain comes! Our improvement will continue to create a better working environment.

 

Knowledge § What will happen to the properties of the resin after heat aging?

When the resin is heated for a long time, the reaction rate may further increase, the appearance will become harder, and the color will become darker. This is a common phenomenon in the initial stage of heat aging. Sometimes small molecules in the resin, such as catalysts, plasticizers, etc., volatilize to the outside of the resin, which will also make the resin hard and brittle. This situation causes the quality of the resin to be lost, often resulting in cracks and deformation in appearance, which is the second common step of heat aging. If the resin structure contains certain functional groups, such as double bonds, an unexpected cross-linking reaction occurs, which will make the resin appear harder and more brittle. However, some structures in the resin, such as ether groups, will break at high temperatures, which may weaken and soften the resin. Even some compositions with a low degree of cross-linking will break down into high-viscosity liquids due to chain scission. In summary, the heat aging properties of resins will vary with the aging stage and formulation composition.

 

Living § But what can I do

One day after getting off work, I saw my daughter lying down and watching TV. The chair was crooked and the cups on the table were not washed after drinking. I asked her, "Why don't you tidy up the living room?" My daughter defended, "I didn't do it!" I told her, "You can also collect it if you didn't do it! This is our home!" Judging from her impatient expression, she didn't quite accept what I said, she was just afraid that I would get angry. There are the same scenes at work. The chairs in the library are messy. If you ask:“ Why is it so messy?” Someone must say:“ the previous user did it” (meaning it was not me), and then find the person in charge of the area. The person in charge said: “I can’t spare time for management because I’m busy with work!” In order to solve the problem, a management method was drawn up: the use of the library requires an appointment to register. Some people proposed to install the monitor, and some people proposed to lock the control to prevent it from being untidy after registration. Calmly think about things that are not your responsibility. We will never be able to deal with it. I saw the library chairs messy in the corridor far away, and I walked over to arrange them. It is not to save the number of cleaning staff, nor to impress the boss. On the one hand, I hope that I will "automatically" do what I do, and I believe that everyone will agree with this attitude to life. Some people think that this kind of idea will not be understood. What should we do if it fails in the future? I thought for a long time and found that this is not my problem. Our society does not lack good ideas. If these ideas are supported by actions, they can grow and thrive. If everyone does not take action, ideals will not have the opportunity to be implemented. So the question is, what is your attitude towards good ideas? Willing to take action? "But what can I do " is a love song. Being human, our ideals are a bitter love for us. (Click on the photo with the mouse to play a song).

—Author: Dr. Ming-Xu, Li


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