As precision equipment for materials research and process verification, the laboratory twin-screw extrusion production line maintains continuous production characteristics while emphasizing controllable parameters, traceable data, and flexible operation. The entire process covers raw material preparation, feeding, melt plasticizing, mixing and homogenizing, molding output, and post-processing, forming a complete chain from initial materials to samples suitable for analysis and evaluation, providing reliable experimental basis for formulation screening and process optimization.
The process begins with raw material pretreatment and precise weighing. The matrix resin, fillers, additives, and functional components are weighed according to the experimental formulation. Hygroscopic materials require pre-drying to ensure the moisture content is within the process allowable range. Powders or granules can be sieved as needed to unify the particle size distribution, reducing the risk of feeding fluctuations and uneven plasticizing. The rigor of this stage directly determines the repeatability of the experiment and the validity of the data.
Then the feeding stage begins. Laboratory extruders are typically equipped with loss-in-weight or volumetric precision feeders to continuously deliver pre-treated material to the twin-screw extruder inlet at a set rate. The stability of the feed rate is monitored in real-time by sensors and forms a closed-loop control system with the extruder main unit, ensuring consistent material input conditions across different experimental groups and providing a benchmark for subsequent process parameter comparisons.
After entering the twin-screw extruder main unit, the material undergoes three stages sequentially: conveying, melting, and mixing. The screw rotates within the barrel, propelling the material. The combined effect of external barrel heating and internal heat generated by screw shearing gradually raises the material's temperature above its melting point in the compression section, completing the solid-to-liquid phase transition. Through combinations of different functional screw elements, high-intensity dispersion and homogenization of components can be achieved in the homogenization section, meeting the special process requirements of high-filling, multiphase blending, or reactive extrusion. This process is crucial in determining melt quality and subsequent sample performance.
The melted and homogenized material is extruded through the die and enters the forming and cooling stage. Depending on the experimental objectives, straight extrusion, sheet extrusion, or granulation auxiliary equipment can be selected to form granules. For underwater or dry-cut granulation, the extruded strip or filamentous melt is rapidly cooled and solidified in a cooling medium or airflow, and then cut into uniform particles by a rotating cutter. Cooling and pelletizing parameters must be matched to the melt viscosity and target particle size to ensure uniform particle morphology and no agglomeration.
The shaped samples then proceed to the collection and post-processing stage. Strips can be directly used for tensile, heat distortion, or flammability testing; particles are dehydrated, dried, packaged, and numbered for melt flow index, mechanical properties, thermal analysis, and microstructure characterization. Throughout the process, parameters such as temperature, pressure, rotational speed, torque, and current are synchronously recorded by an integrated control system, forming a complete process data archive to provide a basis for result analysis and process backtracking.
After the experiment, the equipment must be cleaned and maintained according to procedures to prevent cross-contamination caused by material residue, and the condition of the screw and barrel must be checked to maintain the accuracy and repeatability of subsequent experiments.
Overall, the laboratory twin-screw extrusion production line is characterized by its systematic, refined, and data-driven process, organically combining raw material preparation, feeding, plasticizing and mixing, molding output, and sample processing. It not only reproduces the basic logic of continuous industrial production but also provides a high℃of flexibility and controllability in the R&D stage, thus constructing a scientific and efficient experimental path for the formulation development and process verification of polymer materials.