Torque rheometer experimental parameter setting guide

Publish Time: 2024-11-27

Torque rheometer is a key equipment for studying the rheological properties and processing performance of materials. Reasonable setting of experimental parameters is the core of obtaining accurate and valuable data. When operating, it is necessary to make prudent choices based on multiple factors.

Material properties are the first priority. For low-viscosity fluid materials, such as some hot melt adhesives, due to their good fluidity and low internal resistance, they can withstand higher speeds. It is more appropriate to set the initial speed at 30-50 rpm, which can ensure that the material flows and mixes fully without taking too long due to slow shearing. On the other hand, high-viscosity polymers, such as solid rubber raw materials, are prone to excessive torque at high speeds, which can damage the instrument. It is better to control the speed at 10-20 rpm to ensure that the material is sheared steadily and deformed gradually.

Whether the purpose of the experiment is clear or not is directly related to the parameter setting. If the purpose is to explore the uniformity of material mixing, the experimental time should be long enough until the torque curve tends to be stable from fluctuations. This process may take 20-30 minutes to ensure that the components are evenly dispersed. However, if the focus is on the rheological properties of materials in short-term processing, such as the initial melting performance of thermoplastics, the experimental time can be shortened to 5-10 minutes to capture the torque and temperature changes in the key stages.

Temperature parameters should not be underestimated. According to the melting point and softening point of the material, the processing temperature is often slightly higher than the softening temperature of the material. Taking common polyethylene as an example, the melting point is about 130℃, and the experimental temperature is set to 150-170℃, which can not only make it melt and flow smoothly, which is in line with the actual processing, but also help to accurately present the rheological state.

In addition, the material filling amount is related to the success or failure of the experiment. In the mixing chamber or extruder barrel, if the filling amount is too much, the material will be crowded and the shearing will be uneven; if it is too little, it will not reflect the actual processing situation. Generally, the filling amount is kept at 50%-70% of the cavity volume to leave enough space for material flow and mixing, ensuring that the experimental data truly reflects the material processing characteristics.

Operating a torque rheometer is like fine carving. You need to skillfully set parameters according to the material and purpose, so that you can gain insight into the microscopic world of the material and unlock the optimal solution for processing.