Influence of Processing Glass-Fiber Filled Plastics on Different Twin-Screw Extruders and Varying Screw Designs on Fiber Length and Particle Distribution

Abstract

Due to their valuable properties (low weight, and good thermal and mechanical properties), glass fiber reinforced thermoplastics are becoming increasingly important. Fiber-reinforced thermoplastics are mainly manufactured by injection molding and extrusion, whereby the extrusion compounding process is primarily used to produce fiber-filled granulates. Reproducible production of high-quality components requires a granulate in which the fiber length is even and high. However, the extrusion process leads to the fact that fiber breakages can occur during processing. To enable a significant quality enhancement, experimentally validated modeling is required. In this study, short glass fiber reinforced thermoplastics (polypropylene) were produced on two different twin-screw extruders. Therefore, the machine-specific process behavior is of major interest regarding its influence. First, the fiber length change after processing was determined by experimental investigations and then simulated with the SIGMA simulation software. By comparing the simulation and experimental tests, important insights could be gained and the effects on fiber lengths could be determined in advance. The resulting fiber lengths and distributions were different, not only for different screw configurations (SC), but also for the same screw configurations on different twin-screw extruders. This may have been due to manufacturer-specific tolerances.

Influence of Compounding Parameters on the Tensile Properties and Fibre Dispersion of Injection-Moulded Polylactic Acid and Thermomechanical Pulp Fibre Biocomposites

“…This is due to potentially different screw shapes and dimensions leading to different mechanical shear forces, internal friction, etc. [ 21 ]. However, it can be assumed that the effect directions of the compounding parameters also remain similar when different equipment is used.…”

“…However, using different processing equipment might lead to different biocomposite properties even when the same parameter settings are used. This applies for upscaling from a discontinuous batch compounder to a continuous compounder for larger quantities or when switching to a similar machine from another manufacturer due to specific dimensions of the barrel and the screws [ 21 ].…”

A New Image Analysis Assisted Semi-Automatic Geometrical Measurement of Fibers in Thermoplastic Composites: A Case Study on Giant Reed Fibers

“…Separation of the fibers from the matrix by pyrolysis [9] or chemical dilution [8,13] • Dispersion of the fibers on a surface (2D) or in a liquid or gaseous medium (3D) [14] • Image acquisition by microscopy, laser diffraction or high-resolution scanning [14] • Fiber detection: manually [15] or with the support of automated systems [10] Non-destructive methods are mainly based on micro-CT [16] and advanced automated software for fiber identification, such as MorFi [12,17] or Ellix [18]. However, this method remains challenging [10,19] due to the variation in fiber widths and their intersections [15,20].…”