Development of a Direct Reaction Injection Molding Process for Production and Processing of Long Fiber Reinforced Thermosets (LFD-Injection Molding Process)

M.Sc. Robert Maertens


Thermosetting molding compounds based on phenolic resins are an attractive material for thermomechanically demanding applications and offer weight and cost advantages over aluminum materials. The glass fiber-filled molding compounds are processed in the injection molding process. With the conventional process, based on granular semi-finished products, only an average fiber length of < 1 mm is achieved. However, the fiber length plays a very important role for the mechanical strength of the fiber composite material. Short fiber-reinforced plastics do not offer sufficient high mechanical strength for high stresses, such as those that occur in structural components.


In the project, the approach of a direct fiber feed into the plasticizing unit is to be used in order to achieve a gentle incorporation of the fibers into the phenolic resin matrix. Within the scope of the project, suitable matrix and fiber materials will be selected and analyzed. Based on this, a material formulation suitable for direct processing will be developed. Subsequently, the concept for direct processing in reactive injection molding will be developed and implemented in a prototype machine. With the help of this system, the parameter settings for processing are investigated and optimized and test specimens are produced. The aim of the project is the development of a direct process for the processing of fiber-reinforced thermosets in injection molding and the derivation of the process-structure-property relationship of the material class of long fiber-reinforced thermosets generated in this way.


  • Characterization of thermoset long fiber specimens: quasistatic (tensile, flexural), dynamic (Charpy)
  • Analysis of the resulting fiber length distribution by image evaluation of the ash residue and µ-computer tomography

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