Application Research Of Light Scattering Techniques In Polymer Solution Characteristic Parameter Measurement

In recent years, people has paid much attention to polymer materials because of its special properties and it has been widely used in the chemical industry, pharmaceutical industry, environmental protection and other fields. To prepare the superior polymer materials, particle measurement techniques must be used to monitor the synthesis process. Visible particle measurement technology is very important. Our country attaches great importance to the research of polymer materials, but the backward of the measuring technology and the lack of instruments results that scientific research and production are subject to constraints. The development of measurement technology is extremely urgent. Light scattering technique, with high measuring accuracy, repeatability and fast measurement speed, is a popular technology in the field of polymer solution characteristic parameter measurement.Purpose of this study is the use of light scattering techniques to obtain weight-average molecular weight(wM), mean square radius of gyration(gR) and second virial coefficient(2A)of polymer dilute solutions. Basing on the research of the theory of light scattering, we put forward the solution and build the measurement system. The main contents are as follows:1. The paper analyzes the mechanism of light scattering and researches the current situation of the development of light scattering technology. Mie theory is expounded in detail. According to the theory formula, Mie scattering laws are analyzed. Then it leads to the approximation of Mie theory, namely, the theory of Fraunhofer diffraction and the theory of Rayleigh scattering.Next, the applicable conditions of the two theories are analyzed.2. A variety of light scattering technology applied to measuring the features of polymer solution are researched, and on this basis, the paper gives the solution. First, we make sure the system working principle basing on Rayleigh scattering theory, which provides theoretical support for the subsequent design. Then, the whole measurement system design scheme is completed.3. We do some analysis and verify the system design schemes. First, through the PSpice software simulation, the photoelectric conversion circuit is analyzed, including the DC bias point, bandwidth and circuit noise analysis. The analysis results show that output noise increases obvious an acceleration when circuit characteristic frequency more than 60 Hz. Then through static calibration experiments we get that hysteresis error is 1.76% and repeatability error is 2.81%. Next, we verify the sample rate, the experiments show that the maximum sampling rate can be up to 11 KHz. Through the above work, we ensure that the various modules work independently effectively.4. Finally, the joint-test experiments of various modules of the system are completed. Then weight-average molecular weight(wM), mean square radius of gyration(gR) and second virial coefficient(2A) of polymer dilute solutions are obtained successfully.