Development of polymeric nano-composite fiber based structures for acoustics and filtration applications
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Electrospinning lab-scale experimental set-up was developed for manufacturing polymeric nanofiber composites for acoustics and filtration applications. In this study, nanofiber membranes were fabricated using two types of polymer materials: Polyvinylpyrrolidone (PVP) and Polyvinylidene Fluoride (PVDF). The control parameters of the electrospinning process, including polymer concentration, voltage input, flow rate, needle to collector surface distance, and collector rotational speed, were studied and optimized using Taguchi’s experimental design methodology. The parametric study was performed to investigate the effect of varying the electrospinning variables on the fiber diameter, thickness, and weight of nanofiber membranes, respectively. Statistical models were developed for modeling and optimization of electrospinning parameters using Analysis of Variance (ANOVA), Response Surface Methodology (RSM), and Genetic Programming (GP). The experimental work examined and proposed in this thesis involves developing nanofiber membrane composites from a pure polymeric base, fillers, and layers for two different objectives, including low-frequency sound absorption and filtration applications. Experimental results show that polymer concentration and voltage input were the two most significant parameters that regulate the fiber diameter, thickness, and weight of PVP and PVDF fiber membranes at high significance levels greater than or equal to 95%. Mathematical models developed using RSM show high average accuracies greater than 80% for the respective output responses. Empirical models developed using GP show higher accuracy than RSM models for all three responses generated from the electrospinning of PVP and PVDF fibers. The acoustic performance of the pure polymeric nanofiber composites with micro-scale thickness shows high sound absorption coefficient values close to one at different Back Cavities (BC’s) in the frequency range of 200-300Hz. Filler infused polymeric nanofiber composites show high coefficient values greater than 0.9 at even reduced thickness, compared to pure polymer fiber composites, in the frequency range of 300-500Hz at different BC’s. Electro-spun nanofiber membranes were developed from PVDF polymeric base and anti-viral /bacterial fillers for filtration applications. The layering of these nanofiber composites with surgical masks shows better particle filtration efficiency in the particulate size ranging from 0.3μm to 10.0μm with equivalent pressure drop level of N-95 masks.