Yongkuan Chemical Newsletter-Issue 311
Release Date: 2019-11-04
experimental report § PP adhesive that hardens at room temperature
Polypropylene (Polypropylene, PP)With thermoplastic olefins (Thermoplastic olefin, TPO) 具有易成型、耐化性與成本低等優點。它的缺點是化學結構極性低，很多是結晶性高分子，造成接著的困難。我們正在研發自由基聚合的壓克力接著劑，試圖解決這個瓶頸。將膠塗佈在PP試片上面(圖1)，將兩試片對貼進行室溫硬化(圖2)。試片進行剪切強度拉伸測試，接著劑呈現凝集破壞(Cohesive Failure)。破裂表面橫向的裂紋，表現出膠的韌性：膠體隨著試片拉伸時，一段一段破裂造成的(圖3)。調整膠的韌性與剛度，可以獲得不同的強度。有一些配方在拉伸的過程中，試片產生白化現象(圖4)。這是PP在應力中產生順向結晶的結果，代表樹脂的接著強度已大於PP本身的抗拉強度。目前在室溫硬化、不塗Primer的情況下，實驗中PP接著劑的剪切強度約在35Kgf/cm2 (Figure 5). In the future, there are still some problems that need to be broken through, such as: the problem of oxygen interference, further improvement of strength, application to other non-polar materials, etc., we will continue to work hard.
─ author: Dr. Wu JiaxingAbout Yongkuan § Coastal beach
This is our fourth beach activity. The weather was very hot on that day. After everyone took good protection measures, he walked on the unstable stones for the camp, and worked hard to clean up the garbage. After a lot of hard work, the coast was cleaned. a lot of. Caring for the environment needs perseverance, and we look forward to the next beach cleansing event, with your enthusiastic participation, let us work together for the earth!
Knowledge exchange § Is there any relationship between the initial setting time of MS resin and the adhesive strength?
For ordinary metal and plastic materials, most MS resins have initial bonding strength after 1 hr and can move the workpiece. Some resins can adjust the reaction speed faster, and within 30 minutes there will be strength. There is no certain relationship between the initial curing speed of MS resin and the initial adhesion strength. Initial curing will first occur on the surface, caused by the cross-linking reaction of the resin. The resin mixed with multifunctional groups will reduce the reaction rate required when gelation occurs, and make the initial curing time seem shorter. The initial adhesion strength needs to consider the wetting compatibility of the resin and the substrate, the number of reactive functional groups of the resin, and the polarity of the different MS resins...etc., the concepts of the two are different and cannot be confused.
Biweekly strike § my hometown
My hometown is Macau, a projectile place that is only 1/9 of the size of Taipei City. When it comes to Macau, I believe that the first time you think of the magnificent casino, when I was in college in Taiwan, most people asked me: "Are Macau people gambling very well?" My answer is: "Most of us are No gambling." In addition to the casino, there are many places that deserve everyone's appreciation. Macau was ruled by Portugal for 446 years, so no matter whether it is eating, drinking, playing, culture, buildings, etc., you can see the trace of "Chinese and Western integration".
─ Author: Miss Chen Shi Min