Influence of process parameters on mechanical properties of physically foamed, fiber reinforced polypropylene parts

Abstract

Due to the high complexity of the foaming technology, the relationship between processing and final properties of parts produced is not completely understood. Investigating the causality chain Processing–Morphology–Properties is of great importance, especially for the automotive industry, in order to be able to tailor the mechanical properties of foamed parts. This article examines and qualifies the effects of seven process parameters (melt/mold temperature, degree of foaming, injection speed, delay time, gas content, and back pressure) on biaxial bending and flexural behavior—the predominant deformation mechanisms in interior automotive applications—of foamed plaques, using the MuCell process. The results clearly show that three major factors (mold temperature, degree of foaming, and delay time) have significant impact on the mechanical properties of the foamed parts. For a clear understanding of these interactions, computed tomography scans of certain plaques are correlated to process parameters and mechanical performance. This article should forge a bridge between production and performance. © 2018 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47275.

Microstructure and Properties of Glass Fiber-Reinforced Polyamide/Nylon Microcellular Foamed Composites

“…According to the classical nucleation theory, the increased melt temperature was also beneficial to improve the cell nucleation rate and thus achieve a finer cell structure [ 33 , 34 ]. As shown in Figure 2 c,d, the cell structure was improved when the temperature was increased by 20 °C.…”

Nonlinear influences of process parameters on mechanical properties of physically foamed, fiber‐reinforced polypropylene parts

“…Based on the results from our previous work, [35] the three most important process parameters mold temperature, degree of foaming, and delay time should be investigated in more detail. As these previous experiments did not allow for the detection of nonlinear relationships between processing parameters and final mechanical properties, a full-factorial central composite experimental design was created in this work.…”

“…Also, its interaction with the degree of foaming has a large effect on bending behavior. Based on findings published in our previous work, [35] it is assumed that a finer cell structure develops with prolonged delay…”

“…The present work is an essential extension of one of our recent works, [35] where the influences of seven process parameters on selected mechanical properties were examined. It was found that mold temperature, degree of foaming (i.e., the opening stroke of the mold; increase of final part thickness) and delay time (i.e., the time between injection of the melt into the cavity and the performance of the mold opening stroke) are the most important in terms of bi-and uniaxial bending behavior.…”

Theoretical Background and Automation Approach for a Novel Measurement Method for Determining Dynamic Solubility Limits of Supercritical Fluids in Injection Foam Molding

“…These lower pressures, in combination with the absence of a packing stage (compensated by internal gas pressure), can allow for smaller clamping units. The lightweight potential of foamed components and their easy recyclability (just one material) in addition to improved thermal or acoustic insulation, a better warpage behavior , higher stiffness‐to‐weight ratio or, for instance, higher energy consumption during biaxial bending tests make the technology suitable for a variety of applications.…”