Uday K. Vaidya

Security Challenges of Additive Manufacturing with Metals and Alloys

Cyber-physical systems are under constant and increasing attacks as components of the critical infrastructure. Additive manufacturing systems are a new class of cyber-physical systems that produce threedimensional objects layer by layer. Agencies and companies such as NASA, the European Space Agency, General Electric and SpaceX have explored a broad range of application areas for additive manufacturing, including creating functional parts of safety-critical systems such as jet engines. The range of application areas and dependence on computerization makes additive manufacturing an attractive target for attackers.

Preparation and characterization of flax, hemp and sisal fiber-derived mesoporous activated carbon adsorbents

The first aim of this study was to investigate mesoporous activated carbon adsorbents from sisal, hemp, and flax fibers by cost-effective methods. Fibers were impregnated with low concentration (20u2009wt.%) phosphoric acid. Carbonization temperatures were defined by thermal analysis. Bast fibers (hemp, flax) decompose at lower temperatures (419.36℃, 434.96℃) than leaf fibers (sisal, 512.92℃). The second aim was to compare bast and leaf fibers-derived activated carbon adsorbents by determining physical adsorption properties, chemical compositions, scanning electron microscope, and Fourier transform infrared spectroscopy. Results showed that natural fibers have good candidates to prepare mesoporous activated carbon adsorbents with high surface area (1186–1359u2009m2/g), high mesopore percentage (60–72%), and high C content (80–86%). Even though leaf-derived activated carbon developed more mesoporous structure (72%), bast-derived activated carbons provided higher surface areas (Shempu2009=u20091359u2009m2/g; Sflaxu2009=u20091257u2009m2/g) and C content. Fourier transform infrared spectra for bast fibers-derived activated carbon adsorbents were quite similar while leaf fiber-derived activated carbon adsorbent had a different spectrum.

Utilization of Chicken Eggshell Waste as a Bio-Filler for Thermoplastic Polymers: Thermal and Mechanical Characterization of Polypropylene Filled with Naturally Derived CaCo3

The processing and characterization of polypropylene/eggshell composites was the main objective of this study. Natural source-derived calcium carbonate (CaCO3) was extracted from waste chicken eggshell and compounded with polypropylene polymer. The compound was molded using the Extrusion Compression Molding (ECM) process. X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis were conducted on the eggshell to characterize its constituents. The effects of filler loading, 30 wt.% eggshell and 30 wt.% eggshell with 5 wt.% of maleic anhydride grafted polypropylene (MAPP) on the mechanical and thermal properties were studied. The addition of a small amount of MAPP during melt extrusion improved the dispersion and bonding of CaCO3 particles in polypropylene. 7.49% decrease in tensile strength, 35.51% enhancement in flexural modulus and 66.05% increase in notched Izod impact energy were obtained by adding 30 wt.% eggshell with 5 wt.% MAPP to polypropylene. Adding 30-wt % of eggshell filler and 5 wt.% MAPP to polypropylene delayed the flame propagation time by 99 seconds.

The Effect of Flocculent, Dispersants, and Binder on Wet–laid Process for Recycled Glass Fiber/PA6 Composite

The papermaking industry has been using the wet-laid process to suspend paper pulp-derived fibers in water and drain the solution through a forming mesh. This process has recently been adopted to produce non-woven, wet-laid fiber-reinforced polymer matrix composite mats. The mats can be post-molded into different complex shapes using compression molding or related processes. The objective of this study was to produce composite panels from wet-laid mats and observe the effect of chemicals used during the process on the mechanical and thermal characteristics of the resulting composite. Two sets of mats were processed using recycled glass fiber with Polyamide 6 (PA6). Flocculent, dispersant and binder (poly(vinyl alcohol) (PVOH)) were added to one of the mats, and the second mat was processed without these chemicals. The addition of these chemicals enhanced the fiber distribution and reduced processing defects in the mats. This was reflected in the mechanical properties of the final product. It was noticed that the flocculent, dispersant and binder volatilized during the compression molding step. Hence, the additives were found not to affect the thermal properties of the consolidated part.