Chapter 383： Zinc oxide or stannous octoate?

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"I think zinc oxide (ZnO) should be used as a catalyst. After all, zinc oxide is cheap, and most domestic companies use tin oxide as a catalyst for synthesizing lactide."

"Director Chen, I also know that zinc oxide is cheap, but we have to consider the catalytic effect objectively. I still firmly believe that the catalyst must be stannous octoate (C16H30O4Sn)!"

"Professor Fang, I don't agree with your idea. I also think zinc oxide should be chosen!"

Listening to the discussion inside, Chen Hao probably understood.

"Cough cough."

A sudden cough made Chen Chong and Fang Haosen look over. After seeing the appearance of the person who came, the two stopped arguing and greeted each other.

"headmaster."

"headmaster."

"I heard the voices of the two of you discussing when I was still outside. I almost thought you were going to fight." Chen Hao smiled and joked.

"Principal, you have misunderstood. Professor Fang and I are discussing." Chen Chong explained a little embarrassedly.

Fang Haosen also replied: "Director Chen is right, we just discuss it reasonably, there is no big problem."

"Well, what are you discussing?" Chen Hao smiled warmly on his face.

"That's right, our professor Fang has different opinions on the catalysts of lactic acid oligomers, so no one can't convince anyone." Chen Chong said a little embarrassedly.

"Oh, it's like this." Chen Hao raised his eyebrows and looked very interested, "Then tell me what the two of you think."

Although Fang Haosen has just joined Guanghua University, he also knows that the principal Chen Hao is a great **** in the material industry. After all, the photonic screen was launched by Chen Hao.

Not to mention Chen Chong, as the number two person in the photonic screen technology laboratory, that is the five-body worship of the principal, and it is not an exaggeration to say that he is a little fan.

The two told Chen Hao the cause and effect in detail.

Chen Hao nodded as he listened, but in fact he figured it out when he was eavesdropping.

After listening, Chen Hao looked like he was thinking, and said to the two of them: "I have a general understanding, and I think both of you have good ideas, whether it's Director Chen's zinc oxide route or Professor Fang's stannous octoate. I think the route is fine."

Isn't this nonsense?

Chen Chong and Fang Haosen listened to the black line, and there was no difference between saying it and not saying it.

Looking at the expressions of the two, Chen Hao laughed, "Then divide into two groups, one group uses Director Chen's zinc oxide as a catalyst for synthesizing lactide, and the other group uses Professor Fang's stannous octoate as a catalyst for synthesizing lactide. catalysts for esters."

"I think it's good to have two groups, as a controlled trial."

Chen Hao's words are not without reason, but Chen Chong said with some worry: "Principal, but we don't have many people. If we divide it into groups... I'm afraid it will affect the efficiency."

Fang Haosen also nodded. Although he and Chen Chong had disagreements, both of them aimed to break the lactide technology as soon as possible. After all, the news of Beautiful Country also came to their ears yesterday, and they knew that NatureWorks held a press conference to ridicule them. The school's affairs, it is estimated that the principal is now staring at a lot of pressure.

Fang Haosen didn't hesitate at all, looked at Chen Chong and said, "If that's the case, then I support Director Chen's idea and use zinc oxide as a catalyst!"

There are two main preparation methods, namely lactide ring-opening polymerization method and direct polycondensation method, and the ring-opening polymerization method is mainly adopted in industry.

Lactide ring-opening polymerization method, also known as two-step method, is a process in which lactic acid is first dehydrated to form oligomers, then depolymerized to form lactide, and then ring-opening polymerization is obtained.

The core technology lies in the synthesis and purification of lactide.

The synthesis of lactide is based on the dehydration of two molecules of lactic acid to form lactic acid oligomers, and then the lactic acid oligomers undergo a catalytic transesterification reaction called "back-biting" under the action of a catalyst.

There are many factors affecting the synthesis of lactide, but the main ones are the type and amount of catalyst, dehydration temperature and depolymerization temperature.

In terms of catalysts, there are still many types to choose from. For example, oxides, metal oxides, such as Sb2O3, P2O5, ZnO, SbF3, and tin compounds such as stannous sulfate, stannous octoate, tin octoate, tin lactate, etc.

This is also where Fang Haosen and Chen Chong have differences. The two can be described as twin stars of the lactide laboratory. Anyone who takes one out can be on their own. Each has his own ideas, and it is difficult to convince the other.

Hearing Fang Haosen's words, Chen Chong was also moved, his lips slightly parted, and he asked Chen Hao, "Principal, after all, I came to the school earlier than Professor Fang. I am an old man and I should take a step back. Well, the laboratory No need to divide into two groups, just use stannous octoate as a catalyst!"

Seeing the two give in to each other, Chen Hao laughed dumbly, and waved his hands directly and said, "How about co-authoring with Kong Rong to make pears? I said grouping, which is more reasonable!"

It doesn't really matter who leads the lab, mainly because Chen Hao thinks it's a good idea to divide into two groups and choose different directions.

Different catalysts and different dosages will have different effects on lactide.

For example, too much or too little catalyst dosage will decrease the yield of lactide.

If the dosage is small, lactic acid cannot form lactic acid oligomers with sufficient molecular mass, and there are still many unreacted lactic acid in the distilled product, so the yield of the product is not high.

When the dosage is too large, the dehydration rate becomes faster, and the molecular weight of lactic acid oligomers is too large. Due to the high molecular weight, it is not easy to depolymerize during the depolymerization process in the later stage of the reaction, and it remains in the reactor, which also causes the yield of the product. rate decreased.

Therefore, the choice of catalyst and how much to use is a very strict stress!

"But there are not enough people!" Chen Chong and Fang Haosen looked at each other, and then asked Chen Hao.

"Wouldn't it be nice to select a few from the Photon Screen Laboratory?" Chen Hao said with a chuckle.

Hearing Chen Hao's words, Chen Chong's eyes lit up, this is really a solution.

Polylactic acid is a polymer material, although it is slightly different from the photonic screen, but in terms of experimental operation, we recruit some experimental personnel who are hands-on.

"Principal, I almost forgot! This is indeed a solution!" Chen Chong said excitedly, and the problem was solved.

"Then the two of you will be divided into two groups on the catalyst, and then see which group has the best lactide synthesis, and whoever will follow up the experiment." Chen Hao said and looked at the two of them, and asked with a smile, "Do you see this?"

"Row!"

"I'm OK!"

Fang Haosen and Chen Chong nodded, they were quite interested in the competition proposed by Chen Hao, and they immediately gained more motivation OK, then we are waiting for your good news! "Chen Hao smiled and patted Chen Chong and Fang Haosen on the shoulders.

After talking with the two, Chen Hao walked out of the institute and stood at the door, looking up at the dazzling sunlight.

The reason why I came to the laboratory is to check the attributes of the next two, and then make a decision on who to add epiphany and attribute points to.

Chen Hao shook his head and sighed:

"Old Chen, it looks like I'm sorry for you this time."

ps: Ask for a recommendation ticket, ask for a monthly ticket!

The information on lactide is too hard to find. Finally, I downloaded a few papers on Zhiwang, which made me dizzy. If there is something wrong, don’t take it seriously, I will try my best...

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