Everwide Newsletter No.239

When the epoxy resin hardens, it releases heat, and the total heat released per unit weight of the same type of hardener is almost the same. If it reacts quickly in a short period of time and generates concentrated heat, cracking will occur. We designed experiments for preliminary evaluation: (1) Drop the resin on the glass sheet pasted with Teflon, and put a fixed thickness of the broken glass on both ends of the glass sheet (four thicknesses of 0.5, 1.0, 1.5, 2.0mm) (2) Cover another piece of glass, fix it with a binder clip, and put it in an oven to heat and cure. (3) Disassemble the glass sheet to obtain a test piece with a fixed thickness. For a certain one-component adhesive, the exothermic amount of complete reaction is 630J/g. When baking at 180°C and a fixed weight of 0.2g, the test piece with a thickness of 0.5mm cured well. In the case of thickening with the same weight, the reaction exotherm is very concentrated, causing the temperature of the test piece to rise above the pyrolysis temperature of the resin. Take a 2.0mm test piece as an example, when the temperature rises to 350°C, cracking and scorching appear. This thickness needs to lower the baking temperature to get a good cured product. Further reading: Issue 155: High-strength adhesive with low heat release. Issue 160: Why do some one-component epoxy resins have bubbles after baking? Issue 170: What is the reason for the one-component type to be browned after heating and curing, and even foaming?

—Author: Mr. Gene-Chang, Shi

The trained R&D colleagues will go to various departments for internships, watch the class DVD, and study in the library during the first three months of their arrival in the company. After three months, they will choose a specific time for the exam. From August last year to the present, a total of 10 new colleagues took the exam on January 12, and they concentrated on sprinting in the library one week before the exam (picture on the left). According to statistics, each colleague watched 120 hours of DVD, which is equivalent to more than 6 credits in university, plus 240 hours of self-study. The textbooks are printed on A4 paper and are 8 cm thick. Of course, they will never finish reading. What we emphasize is not memory recitation, what we emphasize is how to reason? How to think? After all, in the real world, the correct answer is groped, not memorized, how to think about this question is often more important than knowing the answer.

Thixotropic is sometimes called thixotropic fluid. Its definition: 1. The viscosity value measured at a fixed shear rate will decrease with time. 2. When measuring the viscosity, gradually adjust the rotation speed of the viscometer from low rotation speed to high rotation speed, and then sequentially decrease from high rotation speed to low rotation speed. If the relationship curve between speed increases and viscosity and the relationship curve between speed decreases and viscosity cannot overlap, the viscosity of the representative fluid will change over time. The fluid that meets these two requirements is a thixotropic fluid, which is a kind of non-Newtonian fluid and is commonly used in adhesives, polymer solutions, etc.

Everwide Fifth Factory is located at the bottom of Dougong 2nd Road. In August 2016, by chance, we contacted the owner and signed the contract in less than a week and the purchase was successful. The former owner of the fifth factory made PVC environmentally friendly plasticizer and helped Rhodia, an international manufacturer to produce. Later, due to the financial tsunami, bank funds were closed, and mainland China cut prices and dumping, the profit margin fell sharply. Finally, because of the environmental protection issues of synthetic raw materials, the owners turned to trade. It happened that our factory space was getting more and more crowded. After seeing their storage space and the use of hazardous materials storage warehouses, we bought it to expand production capacity and raw material storage. The price of land in the Douliu Industrial Zone has been rising continuously. Since we first opened the factory 15 years ago, its price has more than three or four times. The land is getting less and less, coupled with the scattered factory area and increasing management difficulties, so we decided to buy the old factory, clean it up and set off!

—Author: Mr. Ming-Xu, Li

Everwide Chemical Newsletter-Issue 240 is postponed to February 6th because it coincides with the Lunar New Year. Thank you old and new friends for your support and encouragement to Everwide Chemical Newsletter, and I would like to express our gratitude to you! Everwide Chemical Electronic Newsletter production team wishes you good health, peace and happiness, happy every day, and happy new year!