Experiment § Polariscope
Everwide Chemical recently purchased a stress polarizer (left picture). Place a transparent test piece in the light path; photoelasticity will appear in the stressed areas; it is often used to observe the stress of glass and plastic products; we intend to use it to study the influence of manufacturing processes and formulas on stress. The principle of action can refer to the following links: Photo 1: The test piece is very soft when it is higher than Tg, and the stress is very small. Photo 2: Resin shrinks, and stress occurs in the iron ring during cooling. The middle difference line in the photo represents the same magnitude of stress, and the isoclinic represents the same direction of stress. Photo 3: Low temperature will cause the resin to shrink more, and the stress will be greater. The shrinkage stress from high temperature to room temperature will always exist at room temperature; the newly generated stress from room temperature to -20°C will disappear when it returns to room temperature. These phenomenologies make sense in theory, but they feel entirely different when they can be directly observed.
─ Author: Dr. Ming-Xu, Li
Activity § 519 False alarm incident
We have many semi-finished products that need to be stored at a low temperature; they are then placed at room temperature to warm up before production and finally make finished products. The principle of cryopreservation lies in the chemical reaction kinetics: the temperature is reduced by 10°C, and the reaction rate becomes 1/2, so cryopreservation can stabilize the raw materials. In contrast, during the temperature recovery process, a minimal amount of chemical reaction may occur, and a tiny amount of reaction heat will be released. In most cases, these tiny amounts of heat will be dissipated into the surrounding environment without any influence. However, when the mass is large, and the ambient temperature is high, these tiny heats are not quickly dissipated, and their temperature will rise slightly. A slight increase in temperature will induce more reactions, release more heat, and raise your own temperature. This phenomenon keeps repeating; at first, it was only slightly warm, and it may rise to several hundred degrees in the end, causing the entire barrel of raw materials to burn. On May 19th, we had 6kg of semi-finished products in the process of thawing and waiting for production, and the situation as mentioned above occurred. At the moment, we are conducting evacuation and disaster elimination and holding a false alarm event review meeting the next day to promote sensitive materials. Although everyone was a little frightened, if we can improve the omissions in the process, I believe it will be a blessing in misfortune.
Knowledge § What are the ways to reduce UV curing shrinkage and improve adhesion?
When UV hardens, it is easy to produce hardening shrinkage, which reduces the adhesion effect and poor adhesion. On the contrary, reducing the shrinkage during UV curing can significantly improve the UV coating's adhesion. There are three methods used: 1. Use oligomers and monomers with less hardening shrinkage. Generally, the larger the molecular weight, the lower the shrinkage rate; the more functional groups, the higher the shrinkage rate. 2. Filler is used, but it will cause the UV coating to be opaque and avoid precipitation. 3. Use inert resin to reduce the internal stress of the coating film. Inert resin's compatibility with monomers and oligomers should be taken into consideration to avoid poor compatibility, and the physical properties of the UV curing coating will decrease instead, causing adverse effects.
Living § Farming Story
In my memory, Grandpa's generation was helping people race cattle (plowing the fields) to support the family. The generation of Dad also continued to farm. When I was a child, Dad specialized in farming in his own field, growing some fruits and vegetables.
However, the income from farming on one's own fields is limited and can only be used as a side job. When he was in middle school, Dad bought a seedling transplanter that could plant 4 rows of seedlings at a time. It is very tiring to use this rice transplanter because people have to follow the machine and only do 1 to 2 land a day. Later, Dad bought a rice transplanter that people could sit on and plant 8 rows of seedlings at a time. In addition to his own fields, Dad also helps others plant seedlings; when I have free time, I always go to the fields to help. In summer, I got up at 4:30 in the morning to plant seedlings, and it was about 7 when I got home in the evening. Planting seedlings have to endure the wind and sun and require manual assistance (the parts that are not planted by the rice transplanter); the half-dead tired, low wage, and the hard to earn money. The plight of Taiwan's agriculture can be seen from the matter of planting rice seedlings. The cost of one piece of land (293.4 pings; 969.9 square meters) is as follows: 1,300 yuan for farming, 650 yuan for transplanting rice, 800 yuan for seedlings, 1,200 yuan for rice cutting, and 3,200 yuan for pesticides + fertilizer, for a total of about 7,150 yuan. My own wages and water pumping fees when there is a water shortage have not been included in the calculation! One piece of land and one phase can harvest about 800 kilograms of rice and 1 kilogram of rice (wet grain) for about 18 yuan. In other words, the income is only 14,400 yuan. Calculating the two phases in one year, the net income of a land (10 points) is only about 145,000. From these data, we can understand that farmers who grow rice alone may not even support themselves; I really can't figure it out; doesn't it make sense? Food is an irreplaceable material, labor is the supreme value, and agriculture is an environmentally friendly industry that loves the earth. Everyone should pay more attention to the development of agriculture and pay more attention to farmers' income. We should act together to cheer for Taiwan's agriculture!
─ Author: Mr. Yun-Xian, Liu
