Regarding viscosity and molecular weight

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On production lines, quality parameters such as viscosity or molecular weight are generally measured in order to assess the reaction progress of the materials and to enable timely control of the production process. However, as far as is known, most manufacturers rely on offline laboratory sampling and analysis, which introduces a certain time delay. Therefore, online monitoring of viscosity/molecular weight is of great significance for guidance; the basic principle is as follows (the specifics depend on the operating conditions): To improve the reaction efficiency inside the reactor, almost all polymerization reactors are equipped with stirring mechanisms. For a given reaction setup, the torque required for stirring depends on parameters such as the viscosity of the material, temperature, density, liquid level in the reactor, and stirring speed； Unlike ordinary viscous Newtonian fluids, the viscosity of polymers changes with shear rate, and it is necessary to model them using the principles of fluid rheology ； The 3-model requires only three input parameters (introducing additional parameters yields little improvement in measurement accuracy and can be ignored): torque (stirring power), a parameter that indicates the work required for stirring ； Stirring speed, this parameter indicates the magnitude of the shear rate ； For polymer temperature, the effect of temperature on viscosity also exhibits a highly nonlinear relationship, requiring compensatory correction. Experts, do you think implementing online monitoring can be beneficial for production? Please share with us more valuable suggestions! !