Exploring the reinforcing mechanism and micromechanical models for the interphase characteristics in melt mixed <scp>XLPE‐fumed SiO<sub>2</sub></scp> nanocomposites

Radio‐frequency welding shows great potential for a more sustainable manufacturing of lightweight bead foam products based on local dielectric heating of the part. This study provides the first insight into the material‐process interactions required to enable interdiffusion between foam particles and thus adhesion. The complex relative permittivity is analyzed by impedance spectroscopy of the bulk polymer and foam beads using specially designed measurement cells. Due to the increased flexibility of the polymer chains at elevated temperatures, the relaxation mechanisms are promoted, resulting in a shift of the curves to higher frequencies. At a fixed frequency, a peak in the imaginary part is observed above temperature, revealing the superposition of these two parameters. The foamed beads show similar trends with an attenuated signal due to the high volumetric fraction of air within the multiphase system. The linear dependence between and volumetric power as direct process feedback due to dielectric heating was observed during welding. Compared to the delayed signals from the shielded temperature sensors, the analysis of power consumption allows for higher quality real‐time monitoring throughout the process cycle. The correlation also allows prediction of power levels at defined temperatures.

Section: Dielectric Properties Of Foamed Beadsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Dielectric Properties Of the Polymersmentioning

confidence: 99%

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Influence of dielectric properties of polybutylene terephthalate and respective foam beads on process behavior in radio‐frequency welding

Dippold,

Töpfer,

Ruckdäschel

2023

“…24 However, the solid-phase polycondensation process consumes more cost and time and is not suitable for industrial production. Adding fillers (such as montmorillonite, 25 oxide, etc.) to the polymer matrix can be used as heterogeneous nucleating agents to enhance the melt strength and inhibit the collapse of the cell pores, and can also give some functions to the polymer composite.…”

mentioning

confidence: 99%

Foaming behaviors and mechanical properties investigation of high‐strength polyethylene terephthalate/polycarbonate bead foam

Wang,

Xu,

Bai

et al. 2023

Due to the low melt strength, PET foam cells easily grow, and due to the low CO2 concentration in PET, generating more nucleation sites during the foaming process is difficult. As a result, PET foam produced using the supercritical CO2 foaming method possesses a large cell size and a low expansion ratio, which leads to poor mechanical performance. In addition, there has not been much research on how to improve CO2 concentration in PET. In this work, the PC with higher melt strength and CO2 absorption capacity was incorporated into the PET matrix to improve the foaming behaviors of the blend. The results showed that the melt strength and CO2 concentration of PET/PC blends are much higher than that of pure PET. For instance, the melt strength and CO2 concentration of the PET/PC10 blend would be more than twice that of pure PET when the PC content is only 10%wt. By studying the foaming behavior, it was found that high melt strength inhibited the cell overgrowth and collapse of PET/PC foam, resulting in the foam with good cell structure was obtained. In addition, the high CO2 concentration in PET/PC blend is conducive to cell nucleation, thereby increasing the foam expansion ratio during the CO2 foaming process. Finally, the PET/PC blend foam with excellent mechanical properties was obtained. To be specific, the expansion ratio of the PET/PC blend foam was about 9.61, and the average cell size was only 40.38 μm. And the PET/PC blend foam possessed an excellent compressive strength of 7.41 MPa due to the strong interfacial bead cohesion, which showed the application prospect in the field of construction engineering.

Effects of a liquid metal co‐filler on the properties of epoxy/binary filler composites

Kim,

Song,

Kim

et al. 2023

Liquid metals (LMs) with high fluidity and high thermal conductivity (TC) are receiving considerable attention in the research on thermal management polymer composites as alternatives to conventional rigid solid fillers or as co‐fillers to overcome the trade‐off between TC and composite processability at high filler loads. While most previous studies have investigated the effects of LM fillers in soft elastomeric matrices, their effects on the composite properties with rigid matrices, such as epoxy‐based polymers, have not been discussed extensively. Herein, we investigated the effects of LM eutectic Ga‐In (EGaIn) as a co‐filler on the properties of rigid epoxy‐based composites with a binary filler (Al2O3/EGaIn) system. The increase in the volume fraction of LM fillers significantly improves the processability of uncured precursor composites but markedly decreases the mechanical strength of the cured composites at their high loads—the latter effects have rarely been examined in previous studies. However, with adequate LM loads, the composites exhibited superior mechanical properties compared with the all‐solid‐filler system, withstanding a surprisingly high compressive load (~100 kN) under which the all‐solid‐filler system fractured. Furthermore, the epoxy/binary filler composites exhibited reasonably high TC values (~1 W/mK) comparable to that of commercial epoxy molding compounds, suggesting their potential applicability for electronic packaging.