Optimization of Filler Compositions of Electrically Conductive Polypropylene Composites for the Manufacturing of Bipolar Plates

Abstract

In this research, polypropylene (PP)–graphite composites were prepared using the melt mixing technique in a twin-screw extruder. Graphite, multi-walled carbon nanotubes (MWCNT), carbon black (CB), and expanded graphite (EG) were added to the PP in binary, ternary, and quaternary formations. The graphite was used as a primary filler, and MWCNT, CB, and EG were added to the PP–graphite composites as secondary fillers at different compositions. The secondary filler compositions were considered the control input factors of the optimization study. A full factorial design of the L-27 Orthogonal Array (OA) was used as a Design of Experiment (DOE). The through-plane electrical conductivity and flexural strength were considered the output responses. The experimental data were interpreted via Analysis of Variance (ANOVA) to evaluate the significance of each secondary filler. Furthermore, statistical modeling was performed using response surface methodology (RSM) to predict the properties of the composites as a function of filler composition. The empirical model for the filler formulation demonstrated an average accuracy of 83.9% and 93.4% for predicting the values of electrical conductivity and flexural strength, respectively. This comprehensive experimental study offers potential guidelines for producing electrically conductive thermoplastic composites for the manufacturing of bipolar fuel cell plates.

Current status of research on composite bipolar plates for proton exchange membrane fuel cells (PEMFCs): nanofillers and structure optimization

“…Among them, carbon-based llers are the more widely studied ones, such as: (1) multi-walled carbon nanotubes (MWCNTs), 59,60,76 (2) graphene, 60,[76][77][78] (3) carbon nanobers (CNFs), 55,59 (4) conductive carbon black (CBs). [64][65][66][67]79,80 It is worth mentioning that, unlike nanoscale conductive llers, micron-sized carbon bers are oen used in composite bipolar plates not as additives but as the main body of the conductive phase, which plays a role similar to that of graphite. 47,61,63,[81][82][83][84][85] Most nanollers have excellent intrinsic conductivity, which can not only ll the gaps between the particles of composite BPs, but also improve the conductive pathway in the composite BPs, so they can enhance the electrical conductivity of the composite BPs without decreasing the mechanical properties.…”

“…Structure optimization through reasonable methods can improve the performance of composite bipolar plates without changing the graphite/resin raw material ratio. At present, the main directions of structural optimization are: (1) optimization of the dispersion pattern of graphite/ resin, [104][105][106][107] i.e., through physical or chemical means, articially control the dispersion pattern between graphite/resin phases, so that the composite bipolar plate has a strategic distribution of graphite-resin, (2) optimization of the electrically conductive network of the composite bipolar plate: [108][109][110] through the design of electrically conductive paths of the composite bipolar plate, so that the composite bipolar plate has the overall electrically conductive network structure. (3) Interfacial modication and surface functionalization of the llers of the composite bipolar plate 111,112 to enhance the bonding force between the interfaces of the composite bipolar plate and the wettability between the graphite-resin.…”

“…Tariq M. 80 et al investigated the effect of the addition of carbon nanotubes/conductive carbon black on the properties of composite bipolar plates, the aggregation of the morphology of the nanofillers after the addition was investigated, as shown in Fig. 9 , and the effect of the addition of MWCNTs and conductive carbon black on the mechanical properties of the composite bipolar plates was investigated in detail by RSM modeling technique.…”

“…At present, the main directions of structural optimization are: (1) optimization of the dispersion pattern of graphite/resin, 104–107 i.e. , through physical or chemical means, artificially control the dispersion pattern between graphite/resin phases, so that the composite bipolar plate has a strategic distribution of graphite–resin, (2) optimization of the electrically conductive network of the composite bipolar plate: 108–110 through the design of electrically conductive paths of the composite bipolar plate, so that the composite bipolar plate has the overall electrically conductive network structure.…”

Superior Instant Heating and Electrothermal Performances of Interconnected Graphene-Expanded Graphite-Based Electric Heating Composite

“…The conductive properties and electrothermal performances of the electric heating composites are mainly determined by the type, shape, distribution, and resistivity of the conductive fillers, which can be divided into metallic and carbon-based conductive fillers. − By homogeneously mixing the conductive fillers and polymer binders, the contact between the fillers provides the conductive paths required for free electron movement. , Commonly used metallic conductive fillers mainly include metal powders and metal wires . Although a large number of precious metal conductive fillers can be added to obtain good electrical conductivity of electric heating materials, they not only reduce the mechanical properties but also improve the production cost of electric heating materials, which is not conducive to large-scale application.…”