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Everwide Newsletter No.157

Updated: Sep 23, 2021

Experiment § RC value of composite material (Resin Content)

Section of carbon fiber yarn bundle after impregnated with resin, carbon fiber, and resin. Carbon fibers used in sports equipment are mostly yarn bundles composed of monofilaments with a diameter of 7 µm, which are then coated with resin to form a composite structure. From the cross-section of the yarn bundle (Figure 1). Even if the fibers are arranged in a tightly packed arrangement, there must be gaps. Moreover, the carbon fiber is not completely round, the gap will only be more and bigger. When the resin (blue in Figure 2) is added to the carbon fiber, the resin fills these gaps and coats the fiber. The widely used FAW=150g/m² and RC=37% pre-impregnated cloth, the volume occupied by the fiber (black) is 52.8%, and the resin (blue) is 47.2%. Of course. There will actually be some gaps that are not filled with resin. At this time, the average fiber spacing is about 9.2µm. In the final composite molding, part of the resin is extruded under high pressure, and the fiber spacing changes accordingly. Assuming that the resin flow is even, the relationship between the RC value of the final product and the fiber spacing: when the RC value is 30, 25, and 21%. The fiber spacing is 8, 7.7, and 7.5 µm, respectively. As long as the spacing is sufficient, the resin between the fibers can play the role of transferring stress, and the structural strength of the composite material can be displayed. In this case, the lower RC value, the higher the strength of the composite material. How to maintain this spacing evenly during processing? Avoid local lack of glue (spacing is too small) will be the key to whether the strength can be improved.

─Author: Dr. Ming-Xu, Li


Activity § Movie Activities

In order to encourage company colleagues to watch movies more, we have held many appreciation activities. As long as you enter the theater to watch a designated movie, you can receive the movie ticket subsidy with the ticket stub. This year's viewing event is Mr. Po-Lin Chi's " Beyond beauty-Taiwan from above". The film cost 90 million Taiwan dollars and took three years, with a total of 400 hours of helicopter shooting, overlooking the sky, leading the audience to appreciate the beauty of Taiwan. This event also includes a book donation to share with the readers of the biweekly newspaper! As long as you log on to the event website, you will have the opportunity to get a copy of "My Heart, My Eyes, Beyond beauty-Taiwan from above: 20 Years of Perseverance and Affection for Zeppelin Aerial Photography" written by Mr. Po-Lin Chi. Is your heart moved? Hurry up and join our event! For detailed book donation activities, please go to: Note: The pictures and posters of " Beyond beauty-Taiwan from above " used in this issue of Everwide's e-newsletter are all from the " Beyond beauty-Taiwan from above " official website.


Knowledge § What is the particle size distribution of the suitable filler?

According to the experimental results, the dual-distribution combination of the particle size of the filler is better than the single-distribution combination. The filler is mixed in the state of powder and granule, and then mixed into the resin after obtaining a dual-distribution combination and the final effect is better than the dual-distribution effect obtained by mixing two particle size fillers into the resin successively. The so-called dual-distribution particle size is usually ten times the difference between the particle size of coarse particles and fine particles. The weight ratio of coarse particles to fine particles may be between 80:20 and 60:40 because this ratio is close to the densest packing of spheres, so there will be the best results. However, the shape of many functional fillers is not a sphere, so many experiments are still needed to find the best formula. When the filler reaches the ideal particle size distribution, the resin can obtain the lowest viscosity when the filling ratio is the same or the maximum addition when the viscosity is the same. This feature is very important for products that require a high percentage of filling. For example, the thermal conductive glue needs to add alumina to increase the thermal conductivity (75~90wt%), and the packaging material needs to add silica to reduce the expansion coefficient (70~80wt%). In these applications, when filling a high proportion of inorganic powder, it is also necessary to maintain processing characteristics, such as easy application and easy penetration and flow.


Living § Beyond beauty-Taiwan from above

Last Saturday I went to the cinema with a few colleagues to watch the documentary " Beyond beauty-Taiwan from above " and many people, including myself, got their eyes wet. In addition to the beautiful scenery and environmental issues, there are many moving things. A friend wrote to discuss this, and it is suitable to share with you: I went to the theater to watch Mr. Po-Lin Chi’s documentary " Beyond beauty-Taiwan from above " a few days ago. When I finished reading it, a few words appeared in my heart: "Seriously live." I have watched the film’s outdoor premiere in Kaohsiung once, and there were more than 10,000 people on the scene that day. The reason for going to the theater for the second time is that besides wanting to see some details clearly, I also want to sponsor the film again. Later, I bought the original soundtrack and sponsored it for the third time. Encouraging students to watch this film in class is the fourth sponsorship. Why have you sponsored so many times? There is only one reason because Mr. Po-Lin Chi is a "seriously living" person. Video official website: It is not easy for a person to "live" in this world, not just the body, but the soul. Only when a person's soul is alive, that person is truly alive. People who use power as a tool for profit have no soul, those who turn the food industry into a chemical industry have no soul, and those who seek fame by education have no soul. Just because there are many people who have lost their souls in this era, we need to be more alert to ourselves and to live soberly and earnestly. The reason is nothing else, just because we want to "really" live! Go to the theater to watch this documentary filmed for the living you! Singing from Yushan:

─Authors: Mr. Yong-Ao, Fu and Dr. Ming-Xu, Li

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