This work was concerned with evaluating the behavior of thermoplastics reinforced with melt processable phosphate glasses processed by techniques including injection molding, compression molding, and thermoforming. Thermoplastic resins consisting of polyphenylene sulfide (PPS), polyetherimide (PEI) and polyetheretherketone (PEEK) were combined with phosphate glasses having glass transition temperatures (Tg) that ranged from 230-290°C to form composite systems where both the matrix and reinforcing phase were deformable during processing. For the process of injection molding, several factors were examined to maximize the mechanical properties obtained with the addition of the phosphate glasses. The influence of variables such as the glass and matrix viscosity, glass loading, melt temperature, and mold fill rate were examined for a variety of composite blends consisting of the PPS, PEI, and PEEK reinforced with a lower Tg (234°C) phosphate glass and PEEK blended with a higher Tg (282°C) glass. From this work, it was determined that the best mechanical properties were generally produced by using processing temperatures and material combinations that minimized the viscosity differences between the thermoplastic resin and phosphate glass. Variations in the material combinations and processing conditions utilized were also found to result in the formation of a variety of glass phase morphologies that consisted of droplets, ribbons, and an interpenetrating network structure. The addition of the phosphate glass to the neat thermoplastics resins was found to be an effective way to produce injection moldable composite blends. The stiffness of the composite blends increased with glass loading with composites containing up to 45 vol% phosphate glass exhibiting machine direction tensile and flexural moduli in the range of 3-5 times greater than that those of the neat thermoplastics. Additionally, these composites were found to offer moduli and strengths that ranged from 25-50% lower than conventional E-glass fiber reinforced materials of the same loading. The lower mechanical properties of the neat phosphate glasses coupled with a lack of adhesion between the matrices and the glasses helped contribute to the lower mechanical properties exhibited by the phosphate glass reinforced composites. Still, the phosphate glass reinforced blends offered certain advantages including lower mechanical anisotropy, smoother surfaces, and lower viscosities. The processing behavior of phosphate glass reinforced thermoplastics was also examined at temperatures commonly used in forming and shaping operations such as compression molding and thermoforming. It was determined that it was possible to deform the phosphate glass reinforcing phase along with the matrix resin at temperatures only 30-50°C above the Tg of the glass. The deformable phosphate glass reinforcing phase resulted in composite blends that exhibited greater extensibility than a solid E-glass fiber reinforced material. The elongation of the phosphate glass into a higher aspect ratio reinforcing morphology was found to result in an almost 25% increase in the tensile modulus for a polyphenylene sulfide based composite. / Ph. D.

Bauteilkonstruktionen mit integrierten Kunststoffnietverbindungen nehmen aufgrund der steigenden Anzahl artfremder Werkstoffkombinationen im Rahmen von Hybridbauweisen kontinuierlich zu. Als nicht lösbare und punktuell wirkende Verbindung wird das Kunststoffnieten insbesondere aufgrund seiner kosteneffizienten und einfach anmutenden Prozessführung u. a. für die Herstellung von Elektronik- und Sensorelementen sowie für das Verbinden von Bauteilen im Interieur- bzw. Exterieur-Bereich eingesetzt. Aufgrund der hohen Anwendungs- und Werkstoffvielfalt unterliegt der Kunststoffnietprozess jedoch komplexen Anforderungen, die für eine sichere Prozessanwendung durch ein hinreichendes Prozessverständnis sowie eine zielführende Qualitätssicherung kompensiert werden müssen. Die vorliegende Dissertation befasst sich mit der wissenschaftlichen Analyse der thermischen Nietprozesse Warmumformen und Heißluftnieten. Im Mittelpunkt der Betrachtungen steht die systematische Ausarbeitung der Zusammenhänge zwischen dem Verfahrensablauf, den mechanischen Eigenschaften sowie dem resultierenden Versagensverhalten der Nietverbindung. Die Ergebnisse zeigen, dass bei einer optimierten Prozessführung für beide thermischen Nietverfahren hohe mechanische Eigenschaften erreicht werden können. Als dominierender Faktor offenbarte sich die Anbindungsqualität des Nietkopfes an den Nietzapfen, welche in einem direkten Zusammenhang zum Erwärmungs- und Umformverhalten des Nietzapfens steht. Zudem sind die Verarbeitungseigenschaften und die erreichbare Verbindungsqualität vom eingesetzten Werkstoff abhängig. / Due to the rising number of dissimilar material combinations in the field of hybrid design, components with integrated plastic rivet joints are steadily increasing. Among other things, staking is primary used as a non-detachable and point-acting joint for the production of electronic and sensor elements as well as for the joining of components in the automotive interior and exterior by reason of its cost-efficient and seemingly simple process control. However, due to the high diversity of applications and materials, the staking process is subject to complex requirements, which must be compensated by a sufficient understanding of the process as well as a perfected quality assurance in order to ensure reliable process application. The present dissertation deals with the scientific analysis of the thermal staking processes hot forming staking and hot air staking. The investigations focus on the systematic analysis of the relationships between the procedure itself, the mechanical properties and the resulting failure behavior of the riveted joint. The results show that high mechanical properties can be achieved for both thermal staking processes by having an optimized process control. The most dominant factor revealed to be the bond quality of the rivet head to the rivet pin, which is directly related to the heating and forming behavior of the rivet pin. In addition, the processing properties and the achievable joint quality depend on the material which is used.