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Everwide Newsletter No.182


Experiment § The reason why the substrate is difficult to stick

Customers often ask me: "Can your products stick to aluminum?" I replied: "Of course it can!" However, the outer layer of the actual workpiece is wrapped with baking paint, so the thing we really want to stick is the outer layer of baking varnish, which has nothing to do with aluminum. Similar examples are not uncommon. Coating a thin layer of baking paint on the surface of the material often forms a surface with very low surface tension and cannot be wetted. As shown in Figure 1, the transparent liquid on the right is water. Because the surface tension is larger than the baking paint on the substrate, three-dimensional water droplets are formed. The black liquid on the left is silicone oil, because of its low surface tension, the contact angle is almost impossible to measure, but it has a good wetting effect. This experiment can give us some enlightenment on adhesion that is difficult to wet.

  1. Use an appropriate substrate wetting agent to reduce the surface tension of the adhesive.

  2. According to the characteristics of baking paint, it is necessary to match an effective adhesion promoter.

  3. Adjust the curing speed of the adhesive slightly to allow enough time for the adhesive to wet the surface.

Figure 2 shows the appearance of white silica gel coated on the substrate. There is no adhesion effect at all at the beginning, so the gel can be easily peeled off (Figure 3). After using the adhesion promoter, most of the colloid remains on the substrate (Figure 4, the yellow dashed line is where the glue was originally applied). After adjusting the formula, matching the curing time, and using the adhesion promoter, the silicone can become 100% cohesive and can not be torn off, which is the magical place of chemistry (Figure 5).

─Author: Miss. Guan-Ling, Lin

 

Activity § Express compliments to the hard-working clean colleagues

Cleaning and cleaning is very hard work, and everyone who has been a mother knows it. In our more than 3,500 square meters factory, there are three hardworking colleagues who are responsible for company cleaning and provide us with a safe and clean working environment. In addition to routine work, it is also necessary to deal with temporary situations, such as festivals, visitors, or accidental mess, which can really exhaust people. In addition to routine work, it is also necessary to deal with temporary situations, such as festivals, visitors, or accidental mess, which can really exhaust people. Visitors often praise our factory for its cleanliness when visiting the factory, and the accompanying colleagues are also proud of it. The paradox is that the cleaning colleagues who work silently do not know that they have done a great job, and everyone values their efforts. We only use this article to thank them for their hard work over the years.

 

Knowledge § Breaking mechanism of thermosetting resin (1)

The rupture mechanism of thermosetting resin has two categories: localized shear yielding and cavitation. This issue briefly describes the former as follows. Shear yielding refers to the phenomenon that the molecular segments of the resin slide forward in the presence of stress.

Since the cross-linked structure of thermosetting resins is not like the molecular chains of thermoplastics that can slide in a wide range, the shear deformation will only appear in a limited area, especially the shear yielding is different from thermoplastics, which can have a wide range of shearing. From this point of view, the rupture energy of simple thermosetting resins is mostly lower than that of thermoplastics. Thermosetting resins with high crosslinking density and high Tg are not easy to move molecular chains, so the fracture energy will be relatively low. So for the same reason, introducing soft and long chains into hard thermosetting resins can increase the rupture energy.

 

Living § Kinmen's battlefield style

I went to Kinmen for the first time in my life in July this year. Before I set off, I embarked on this unknown journey with the idea of "being deceived at least once in my life". I guess that should be a less fun place! But after a trip of three days and two nights, I feel that Kinmen is a place frozen in time and space, and I am deeply fascinated by it. The rare historical battlefield in the world is still intact before the eyes of the world after more than 50 years. We visited several tunnels and civil defense tunnels along the coast. Based on the traces left over from the excavation of the rock wall, we can imagine the hardships of the garrison. Through the telescope at the observatory, we can see the prosperous Xiamen. The small island of Kinmen, under the ruthless artillery fire, has survived the bombardment of more than 400,000 shells. The small island of Kinmen, under the ruthless artillery fire, has survived the bombardment of more than 400,000 shells. The way of life of the Kinmen people is different from the way that the general islands rely on people who go fishing for their livelihood. Because of the poverty on the island, the descendants of Kinmen went to Beijing in ancient times to rush to get a scholar, and even went to Southeast Asia to develop trade, and after success, they returned to their hometowns to develop. Kinmen seniors have endless stories and countless historical traces. The cultural and historical preservation of Kinmen is very precious, and it is very worthwhile to travel slowly. When will you go there too? For the story of Kinmen, you can refer to: http://www.epochtimes.com/b5/8/8/23/n2238780.htm

─Author: Mr. Xu-Hui, Li


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