How to control molecular weight and molecular weight distribution when preparing polymer materials?
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The molecular weight and molecular weight distribution of polymer materials have a great influence on the properties of the materials. When polymerizing monomers to prepare polymer materials, how are the molecular weight and molecular weight distribution controlled? Please give me some advice, thank you!
The size and distribution of molecular weight are mainly controlled by adjusting the amount and method of monomer addition, the reaction temperature, pressure, catalyst dosage and addition method, the amount of molecular weight regulator, and the terminator.
In short: Through synthesis process.
As mentioned on the second floor, temperature, catalyst concentration, pressure, etc. will all have a great impact. The author should be more detailed. After all, there are not so many variables in specific production. Usually, methods that are more convenient for production are used.
It mainly depends on what materials you want to produce? What method to use. If it is a gas phase reaction, it is easier to change the pressure. Changing the temperature and catalyst dosage are also good. Look at the cost. If it is a liquid phase reaction, it is better to use a terminator. It is also possible to control the reaction temperature and time. It would be unwise to use controlled pressure. In a word, as long as it saves money and the quality is good.
Process synthesis, and your detection methods to control polymers and troubles
For some materials, such as those that are shear-sensitive, they can be controlled by changing the shear rate during processing. This is also related to the material you want to process. The specific materials and environment need to be considered.
This is achieved by controlling the conversion rate of the polymerization reaction, reaction time, catalyst addition, molecular regulator addition, and terminator addition.
Free radical polymerization is more difficult to control, while solution polymerization is easier
There are many aspects, such as reaction time, addition of initiator, etc., all have an impact.