PA66 engineering plastic is a high polymer with a relatively high molecular weight. The molecular weight directly affects its physical and chemical properties such as mechanical strength and heat resistance. The method of estimating molecular weight is to determine the relative viscosity of high polymers. Therefore, in the production process of PA66 engineering plastics, relative viscosity is a very important production index. Viscosity measurement is very important for guiding production, stabilizing production, and ensuring product quality. Meaning, how to measure the viscosity of nylon 66 in the actual production process?

The method commonly used for engineering plastics to determine the relative viscosity of PA66 engineering plastics is the capillary viscometer method. This method is mainly divided into three steps: sample preparation, dissolution and measurement. The detailed measurement principle is to dissolve engineering plastic slices into 96% concentrated sulfuric acid. In, at 25°C, a Ubbelohde viscometer is used to measure the flow time of the solvent and the flow time of the solution. The ratio of the two times is the relative viscosity of the PA66 engineering plastic. In the process of measurement, the instruments and equipment that need to be prepared include analytical balances, dispensers, constant temperature baths, and Ubbelohde viscometer with capillary inner diameter of 1.03mm; the solvent that needs to be prepared is concentrated sulfuric acid with a concentration of 96%, in order to ensure the measurement results For accuracy and reliability, it is necessary to ensure that the measurement equipment and solvent meet the measurement requirements.

In the process of blending PA66 engineering plastics with concentrated sulfuric acid, temperature control is very important. If the temperature is too low, the dissolution speed of the sample will slow down; if the temperature is too high, the sample will have a degradation response during the dissolution process, resulting in a low relative viscosity of the sample; it can be seen that the dissolution temperature will affect the relative viscosity measurement results of PA66 engineering plastics Accuracy and repeatability.