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. 2019 Nov 17;11(11):1896.
doi: 10.3390/polym11111896.

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Gethin Llewelyn  1 , Andrew Rees  1 , Christian A Griffiths  1 , Martin Jacobi  2
Affiliations

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Gethin Llewelyn et al. Polymers (Basel). .

Abstract

Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical N2) and a novel hybrid foaming (combination of said chemical and physical foaming agents). Three weight-saving levels were produced with the varying foaming methods and compared to conventional injection molding. The unfilled PP foams produced through chemical blowing agent exhibited the strongest mechanical characteristics due to larger skin wall thicknesses, while the weakest were that of the talc-filled PP through the hybrid foaming technique. However, the hybrid foaming produced superior microcellular foams for both PPs due to calcium carbonate (CaCO3) enhancing the nucleation phase.

Keywords: TecoCell®, MuCell®, talc; calcium carbonate; foam-injection molding; polypropylene.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Pressure-Volume-Temperature data for unfilled PP and talc-filled PP.
Figure 2
Figure 2
Mold setup with cooling channels and mold features including gate, injection and pressure/temperature sensor locations, and the region where samples were cryogenically prepared.
Figure 3
Figure 3
Recorded and predicted Ultimate Tensile Strengths for both polymers.
Figure 4
Figure 4
Recorded and predicted Maximum Flexural Strength for both polymers.
Figure 5
Figure 5
SEM images of unfilled PP cross-section (white bar indicates 100 µm).
Figure 6
Figure 6
SEM images of talc-filled PP cross sections (white bar indicates 100 µm).
Figure 7
Figure 7
Young’s Modulus (E) against weight-saving (a) unfilled PP (b) talc-filled PP.
Figure 8
Figure 8
Ultimate Tensile Stress (Su) against weight-saving (a) unfilled PP (b) talc-filled PP.
Figure 9
Figure 9
Maximum Flexural Strength (σfM) against weight-saving (a) unfilled PP (b) talc-filled PP.
See this image and copyright information in PMC

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