Experiment § Measurement of Poisson's ratio
The relationship between Poisson's ratio and tensile deformation, Stretching rate. Poisson's ratio refers to the ratio of the material's transverse deformation to the longitudinal deformation when the material is stretched or compressed (Figure 1). The material whose volume does not change during the deformation process has a Poisson ratio of 0.5. Ideal rubber and incompressible materials have this characteristic. The Poisson ratio of most materials is less than 0.5, and there will be volume expansion during stretching. Taking epoxy resin as an example, Poisson's ratio is often around 0.35. It is not difficult to measure Poisson's ratio. We only need to attach a strain gauge to the tensile test piece and measure the transverse and longitudinal deformation during the tensile test (Figure 2-5). Poisson's ratio is affected by temperature and measurement conditions (Figure 6). It is used when calculating the fracture energy GIc. For further reading, please refer to Issue 206.
—Author：Mr Zhan-Yu, Chen
Activity § Cleaning of the manufacturing department
We will clean up at the end of each year to give the factory a new look. However, there are so many items of raw materials in the kegs, and there is no way to take such details into account in the busy cleaning. We specially selected two days this month to suspend all production and reorganize it together. All the raw materials were removed, the outside of the box was thoroughly cleaned, the storage space was re-planned, and then they were placed neatly. Cleaning up on this scale is not an easy task, and colleagues go home tired and fall asleep. Everyone has the same consensus that working happily in a good environment is worth the hard work of a few days.
Knowledge § What is the cause of agglomeration of acid anhydride curing agent?
There are two types of curing agents for epoxy resins, which are acid anhydride curing agents and amine curing agents. The anhydride is formed by the dehydration reaction of a dibasic acid, so it is easy to absorb moisture in the air to generate dibasic acid. The problem is that the product dibasic acid after the acid anhydride absorbs water cannot be dissolved in the original acid anhydride, so the initial stage of the acid anhydride absorption appears to be a little turbid and precipitates, and more serious it looks like agglomeration. The agglomeration phenomenon is especially obvious near the bottle mouth. The mechanical strength and electrical properties of the cured product formed by the reaction of the acid anhydride and epoxy resin after moisture absorption will deteriorate. Therefore, the bottle mouth must be closed tightly at ordinary times. If the acid anhydride tends to be cloudy, do not use it. Further reading: Please refer to Issue 32 for the cause of agglomeration of amine curing agents.
Living § Finding Home in Memory-Wansei’s Story
Wansei refers to the Japanese born in Taiwan during the Japanese Occupation era, with a total of 198,000 people. They were born and raised in Taiwan and must leave Taiwan after the war. They thought they would have new hope when they returned to the mainland (Japan), but they had no choice but to face isolation and indifference. The story of Wansei has been silent for nearly 70 years in the great era. Almost no one understands it in Taiwan or Japan. It is hard to imagine their mood back then. It wasn't until the recent publication of the works and movies of "Wansei Back Home" that everyone understood this history. The author Tanaka Minorca was born in a Wansei family and only learned about his family background when his grandmother passed away. She didn't want this past to be buried, so she spent all of her savings to lead the Wansei grandparents back to Taiwan to find families, visit childhood friends, and find the past in memory. Many people apply for the birth certificate in Taiwan that year, because this paper records all the memories of the family in Taiwan. In the movie, a Wansei grandma said: "Seeing this birth certificate is like reuniting with her family." At this time, the audience felt the same way, and their eyes turned red and tears flowed out. At the end of October, we held a "Wansei Back Home" seminar. Teacher Tanaka told us many stories. Several Wansei found their relatives and friends, but many things changed. The old man regretted that he passed away without fulfilling his wish. No matter what the result is, the story itself makes us feel "love". Teacher Tanaka finally emphasized: "A person who can give others happiness must also be happy." He also borrowed the words of a Wansei: "Being born and growing up in Taiwan is a very happy thing. We must cherish Taiwan.
—Author：Miss Heng-Rong, Li
Remarks: "Wansei Back Home" was nominated for the best documentary at the Golden Horse Awards. Please come to the cinema to support this good movie!
Screening theater query: https://goo.gl/iWCDTB
