Experiment § PU-type moisture-curing coating adhesive
PU-type moisture-curing coating glue uses -NCO at the end of the molecular chain to react with water to form a film. In the pre-polymerization stage, in order to increase the molecular weight, polyols can react with isocyanates. When NCO/OH>1, the product will have the characteristics of moisture-curing. The characteristics of the cured film can be changed by adding additives or adjusted by using different types of isocyanates and polyols. The characteristics of different polyols are shown in the table on the right: PU-type moisture-curing coating glue can be coated on aluminum sheets, glass, iron sheets, and other sheets. After curing, it will form a waterproof and wear-resistant protective film on the surface. The following picture shows the appearance of the iron sheet after immersing it in resin, then placing it at room temperature for moisture curing, and finally soaking it in water for three days. The colloid coated on the surface is transparent and has no white fog, and the iron sheet inside has no rust, which proves that the resin has good water resistance and waterproofness after moisture curing. In the future, this glue can be applied to the protection of printed circuit boards to protect precision circuits from moisture and dust.
─ Author: Assistant R&D Engineer Mrs. Zhi-Xian, Chen Everwide
Chemical
Activity § ISO 9001: 2008 renewal passed
Everwide Chemical conducted an annual routine external audit of the ISO9001 quality system on December 8, 2010. It happens to be a re-evaluation and staff expansion that happens only once every three years. This year, three audit teachers came together to make a comprehensive evaluation of the system architecture of each department. In 2010, through the joint efforts of all my colleagues, a beautiful transcript was handed in and passed the re-evaluation smoothly! In the next year, Yongkuan Chemical will adopt the improvement suggestions provided by the auditors, implement the quality policy of "R&D and innovation, improve customer value", make continuous progress, and continue to work hard for the goal of improving customer satisfaction.
─Author: Quality Management Representative Ms. Yu-Zhi, Ai Everwide Chemical
Knowledge § How to improve the adhesive performance according to the shape of the fracture surface of the adhesive test piece?
The morphology of an adhesive test piece after rupture can provide very important information, which can be classified as follows:
1. Adhesive delamination is the case where one side of the adhesive test piece is glued, and the other side is not glued. The adhesive strength of the adhesive to the substrate must be improved first. At this stage, the goal of development should strive to make both sides of the cracked surface of the adhesive test piece stick to the glue.
2. There is glue on both sides of the broken surface of the adhered test piece, the surface of the test piece is smooth and flat, and there are tiny cracks on the front end. This phenomenon represents that the adhesive test piece is under force, and when some cracks start to occur at the front end, the cracks can quickly grow and form a common plane to minimize the fracture energy. In other words, the adhesive itself at this stage is too brittle and lacks toughness, so the fracture energy is too low.
3. There is glue on both sides of the cracked surface of the adhered test piece, and the surface is extremely rough with undulations, even standing up like scales. This phenomenon represents that the adhesive has a high tolerance for cracks that appear when the adhesive test piece is subjected to force. The number of cracks will increase with the increase of stress, but the generated cracks cannot grow quickly. Until the adhesive can't bear the limit, these cracks that exist everywhere in the adhesive spread out on different planes at the same time, resulting in an extremely rough cracked surface. In other words, this stage represents that the adhesive has excellent toughness, maximizes the fracture energy, and can obtain the ideal adhesive strength.
Living § Fascinating solar system (1)
I remember when my teacher explained the universe, the Milky Way, and the solar system when I was a child, I felt very abstract because I didn't learn the earth sciences very well at the time. Through this experimental class, I decided to understand all these vague concepts. First of all, how to introduce the relationship between the sun, the earth, and the moon in an easy-to-understand way? Zhiyun's mother borrowed a set of three-dimensional models of the sun, the earth, and the moon from the school, and the earth revolves around the sun through the drive of gears. The moon will also revolve around the earth, and we can also explain the changes in the four seasons of the earth in spring, summer, autumn, and winter, and the reasons for the formation of eternal day and eternal night at the same time. Moreover, the reasons for the formation of solar and lunar eclipses can also be answered by rotating the model. I remember my teacher told me when I was young that the moon we see on the earth is all on the same side, but I have long forgotten why this is the case. This time I made a mark on the moon model, that is, when the earth revolves around the sun, the moon also revolves around the earth at the same time. Because when the earth rotates, the moon also rotates. At the same time, the earth revolves around the sun. We observed that the moon always faces the earth on the same side when the model is running. The universe is really amazing, and the never-ending movement between them is truly breathtaking. I think that if you just talk to children, they will have limited absorption and feel very abstract. If you let them use the operation of the model to explain it by themselves, it will be much more impressive.
─Author: Ms. Miao-Ling, Lin R&D Engineer, Everwide Chemical
