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Everwide Newsletter No.296


Experiment § UV LED lamp wavelength and energy

Many light-hardening devices replace traditional mercury lamps with UV LED lamps, and their wavelength distributions are quite different (Figure 1). If a 4-band illuminance meter (Figure 2) is used to measure the intensity of different ranges, the result is as shown in (Figure 3). The different intensity of the same wavelength also makes the physical properties of the UV glue different. Taking (Figure 3) mercury lamp and 365nm LED lamp as examples, the intensity of UVA is 423 and 3851 mW/cm2, respectively. A certain formula has good intensity when exposed with the former, and only a viscous product is obtained with the latter (Figure 4). This phenomenon is not the result of incorrect wavelength and incomplete response. Very strong light will make the UV glue of the acrylic system react quickly, but the molecular weight will drop. The most extreme example is the viscous product. The solution is to increase the irradiation distance, reduce the illuminance, or adjust the content of the initiator. There are many variables between the resin and the light source, which requires careful clarification.

─Author: Tung-Chi, Pan

 

Activity § Charity Road-Running

Swiss priest Wu Daoyuan founded the Meishan Foundation. Last year, the first charity founded the Meishan Foundation, and last year held the first Meishan Cup Charity Road Running Event, so that everyone can be healthy while doing charity. We will participate in this charity activity once again after this year. Before leaving, everyone was full of energy, eating the delicious meal prepared by the organizer, and soon drove away the fatigue of getting up early in the morning. Although it was raining heavily in the process, our enthusiasm was still not extinguished. Colleagues smiled and said goodbye! Attending this activity let us realize the importance of helping each other: our small input, maybe others will have a great feeling! We will continue to do it.

 

Knowledge § Can epoxy resin cure with moisture?

Few people know that it can carry out moisture hardening reaction with ketimine substances. This formula is usually a single-liquid form. When exposed to moisture, ketimine will react to form amines and ketones: the former is a hardener for resin; the latter acts like a solvent and will evaporate into the air. This formula is suitable as a primer, it has the following disadvantages: the effect of too thick film is not good, the bottom is not easy to react; the speed of hardening is slow; the hardened surface often has traces of hygroscopic whitening; the cost of ketimine is high , Very low selectivity; the reaction produces organic volatiles... etc., so it is not common in the market.

 

Living § The Book Review

The author of the book is an economist who writes fables in the current state of society, hoping to give readers insight into the economic laws of daily life. The story of the book: There are three people living on a tropical island, and they only do one thing "fishing" every day. Because they have no tools and can only fish with their bare hands, one person can only catch one fish a day, which can provide the vitality of the day. One of them decided to make fishing net. Unfortunately, it takes a day to make fishing net, and no one can give him fish to eat. Fortunately, he succeeded! The fishnet can catch two fish a day, and he gets the time outside of catching the fish. This story requires readers to think between giving and seeing, and seeing the overall problem behind the matter. Another story in this book is also very interesting: a craftsman who makes canoes, not everyone can afford it, but some people are still willing to pay. Under an opportunity, the craftsman purchased new manufacturing equipment and made a price reduction decision. This change not only improves efficiency but also increases orders. It does not hurt but makes profits, benefiting more people. These stories let me learn to use limited resources to improve efficiency and achieve the ability to play more than a dollar. To understand the value of money, you also need to know your own value.

─Author: Chu-Chun, Tai


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