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.
The versatility of the fiber reinforced composites has significantly replaced some of the sophisticated metal components in certain sectors of industries. The matrix could be altered to improve self-properties via silane modifiers by forming chemical linkages with the matrix in harmony with the reinforcing agents. This research work is an endeavor to enhance the traits of Vinyl ester by scrutinizing the influence of silane chemical agents using Hexamethyldisiloxane (HMDS). The dispersion time and concentration of these chemicals in matrix were optimized and henceforth a natural reinforcement, Abaca fabric was incorporated to constitute Natural fiber composite via Vacuum Assisted Resin Transfer Molding (VARTM) technique. The effect of resin modification on mechanical, thermal, and physical properties of Vinyl ester/Abaca (VE/AF) composite was examined. HMDS resin modified composite showed an improvement in the mechanical and flame retardant properties when compared to the pristine composite due to the formation of siloxane bonding which is compatible with the functional groups of both the matrix and the fabric. FT-IR and FESEM characterizations have showed imperative evidences to support the results. This investigation provides a channel for enhancing the properties of natural fiber composites via chemical modification technique. K E Y W O R D SAbaca fibers, flame retardancy, Hexamethyldisiloxane, mechanical properties, Vinyl ester
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.
Despite being inexpensive and robust, steel cord reinforcements are often prone to pose risks to user health and safety in some industrial applications such as escalator handrails and rubber conveyor belts. Steel cords can reduce the overall stability and performance of the application over time due to their inherent creep accompanied by cyclic thermal expansion and contraction. In this context, this research focuses on replacing steel cords in some critical thermoplastic polyurethane (TPU) composite applications with continuous sustainable alternate synthetic fibers that possess high specific strength (e.g. carbon, glass, and Kevlar fibers). The first part of this research characterizes the effect of epoxy coating on synthetic fibers alone by studying their mechanical properties before and after modification, whereas the second half of the research involves reinforcing a TPU matrix with raw and epoxy-coated synthetic fibers to fabricate fiber-reinforced composites by compression molding. The effect of the curing temperature of epoxy on the end performance of the manufactured specimen was also tested. An in-depth analysis of mechanical and morphological studies showed that, at almost the same volume fraction of fibers, the TPU reinforced composites with modified carbon fibers showed higher load-bearing capacities than steel cord-based analogs. Conversely, a wide variety of other relevant industrial and commercial applications can potentially draw significant benefits by implementing these modified carbon/TPU composites instead of steel cords.
Self-reinforced polyester composites (SRPCs) with light weight, high mechanical properties, good interfacial bonding, and easy to recycle at the end after use have been developed to replace traditional synthetic fiber-reinforced plastics. This study is on fabrication of SRPCs is performed using polyethylene terephthalate (PET) as matrix and polybutylene terephthalate (PBT) as reinforcement material through compression molding via film stacking method. The compression molding parameters such as temperature, pressure, and dwell time were optimized by Taguchi method, and these values are 225°C, 8 MPa, 5 min for tensile strength, 225°C, 5 MPa, 15 min for flexural, and 215°C, 3 MPa, 5 min for impact test. Flame retardancy in SRPCs has also been introduced as a new idea to minimize the flammability nature and is helpful in engineering applications. Flame retardants (FRs) such as ammonium polyphosphate (APP), zinc borate (Zb), and magnesium hydroxide (Mg(OH) 2 ) were used. The flame retardancy mechanism of optimized SRPCs works effectively which was evident by horizontal burning and LOI test. Thermogravimetric analysis (TGA) was also studied to confirm the thermal properties of the composites. Mechanical properties were reasonably affected by the FRs as confirmed by field emission scanning electron microscope (FESEM). K E Y W O R D S flame retardants, mechanical properties, self-reinforced polyester composites, Taguchi method, thermal analysis | 2437 WEI Et al. How to cite this article: Wei Z, Syed NA, Muhammad L, Jung-IL S. Fabrication of self-reinforced polyester composites and their mechanical and flame retardant properties.
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