Experiment § Control of thixotropy and vertical flow.
Toothpaste and creams are thixotropic. When they are stirred, their viscosity decreases and they can be applied easily. But once the external force disappears, the viscosity will increase, and it will be fixed wherever it is applied. Many adhesives and coatings also exhibit this characteristic. There are several ways to make thixotropy, the most common is to add a thixotropic agent to the resin, such as fumed silica. When the resin is stressed, the small particles of these thixotropic agents can be more uniformly dispersed, so the viscosity is low. When the resin is left standing, there is a special attraction between these particles, and they will attract each other and arrange to divide the liquid in a grid-by-grid structure, and the liquid will not flow arbitrarily, and thixotropy will occur (Figure 1). However, the attraction between these particles is not permanent. They may react with the resin and be replaced, and they may also be weakened due to the increase in temperature, resulting in the destruction of each grid structure and the occurrence of vertical flow (Figure 2, 3). Long-term stable thixotropy mainly needs to maintain the attraction between particles. In addition to formula research, cryogenic storage is also a method, because the low temperature can slow the reaction, so thixotropy is easy to maintain.
—Author: Miss Ming-Xiu, Lai
Activity § What happened in September
In the summer, the interns of Huwei University of Science and Technology are about to start school. Before they return to school, we will explain to them the application of materials (Figure 1). In the fight against heat, the temperature must be lowered by 0.5°C every year. This year's theme is to increase the area of the open-ground shading net to isolate the heat source (Figure 2) and fill in the area where there is no ceiling in the factory building (Figure 3). We used ropes to straighten all the trees that were dumped by the typhoon, and now many trees have grown new leaves (Figure 4). As the students start school, we have a staff tour in early September, mid-September, and late September, and the name of the activity is called "Learning Journey" (Figure 5). In addition to these activities, there will be annual supervision and inspection of the quality system, preparations for the October Taipei International Electronics Show and other tasks. September is really busy!
Knowledge § What is creeping?
Creep is a phenomenon unique to polymer viscoelasticity, which refers to the relationship between dimensional change and time when a material is subjected to a fixed force. For example, if you hang a heavy object under the rubber band, the rubber band will have a specific elongation in an instant, but as time increases, the length of the rubber band will gradually increase. Microscopically speaking, the polymer chain will rotate the bond angle and bond length (elasticity) due to a sudden external force, but it will also slide the molecular chain (viscosity) along the direction of the external force. From another point of view, variables that increase the sliding ability of molecular chains will increase the degree of creep, such as lowering Tg, lowering crosslinking, prolonging time, increasing load, and increasing temperature.
Living § Interesting self-guided travel in Japan
Since the end of the semi-self-service travel in Russia six years ago, I have been looking forward to one day that I can also take a full self-service journey. In order to avoid getting lost, I chose the country where self-service travel is the easiest for touchdowns: Japan. A lot of preparations were made before departure, including looking through travel books and checking website information and for example, backpack inn, Lonely planet. Of course, Google map is also a great tool, because I have already seen the street view map beforehand, so when I was looking for a road in Japan, I was very familiar with it, and there was no worry of getting lost at all. The most worrying issue in self-service travel is language communication. This trip is mainly in simple Japanese, and many Chinese characters in Japanese are the same as Chinese, so it will not be difficult to read. In an emergency, I will try to talk in English. Some people worry that Japanese people’s English is not good, but after my experience this time, I feel that Japanese people’s English is actually very good! When we ask questions in English, they will answer them patiently. One day when I took the subway, I didn't know that the train had reached the terminal. Then a Japanese office worker ran over to us and said, "This is last!" so we got off the train quickly. There was another similar situation. We were still looking at the map in the car to study the route. Then there was a mother in the car taking me by the hand and kept speaking Japanese who hold a child. I finally understood that she was telling me that the train had arrived at the terminal. These few experiences have moved me very much, and I deeply realize that as long as there is a heart, there are many good ways of communication besides language. Self-service travel can experience another country in depth and is a completely different travel experience. Maybe you can try it next time!
—Author: Miss Heng-Rong, Li
