Summary
In this research study, electrically conductive Polypropylene (PP) based composites were developed using twin‐screw extrusion technique with the objective of investigating the effects of primary and binary fillers on the overall electrical performance of the composites with relation to their mechanical properties. Thermoplastic polymers are suitable for a wide variety of applications due to their inherent characteristics, such as low density, ease of processibility, and recyclability. The addition of conductive fillers to thermoplastic resins reduces the material's resistivity and provides the ability to conduct heat and electricity, making them an excellent candidate for the manufacturing of fuel cell bipolar plates. The first part of this research study consists of studying the effect of graphite content on the electrical and mechanical properties of PP composites, whereas the second part focuses on the analysis of the effects of a multi‐filler composite system consisting of Multi‐Walled Carbon Nanotubes (MWCNT) and Carbon Black (CB) in the graphite‐PP composites. The experimental results revealed that the maximum electrical conductivity obtained from the binary filler composites is up to 127% higher compared to that of the single filler composites. The addition of binary fillers also improved the flexural strength of the composites. This experimental study constitutes new prospects in the development of electrically conductive thermoplastic composites with sound mechanical properties for fuel cell bipolar plates.
In this study, the polymeric nanofibers of polyvinylpyrrolidone (PVP) were manufactured using the electrospinning technique. The electrospinning process parameters such as voltage, polymer concentration, rotational speed of the collecting drum, collecting distance, and flow rate were optimized to obtain the minimum fiber diameter for sound absorption applications. The effects of these parameters on the fiber diameter as output responses were investigated by analysis of variance (ANOVA) and Taguchi’s array design. Furthermore, a mathematical model was generated using response surface methodology (RSM) to model the electrospinning process. The high voltage and polymer concentration were observed to be the most significant parameters at 95% and 99% confidence level. The average model accuracy of 83.4% was observed for the predictive model of electrospinning which is considered acceptable as it is composed of complete experimental trials of 27 out of 243 runs. The experimental study offers a promising attempt in the open literature to carefully understand the effect of various electrospinning parameters when producing PVP nanofibers.
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.
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