Browsing by Author "Chi, K. -H."

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Characteristics of trace metals in traffic-derived particles in Hsuehshan Tunnel, Taiwan: size distribution, potential source, and fingerprinting metal ratio
(2015-01-01)
Lin, Y. -C.
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Tsai, C. -J.
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Wu, Y. -C.
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Zhang, R.
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Chi, K. -H.
Traffic emissions are a significant source of airborne particulate matter (PM) in ambient environments. These emissions contain an abundance of toxic metals and thus pose adverse effects on human health. Size-fractionated aerosol samples were collected from May to September 2013 by using micro-orifice uniform deposited impactors (MOUDIs). Sample collection was conducted simultaneously at the inlet and outlet sites of Hsuehshan Tunnel in northern Taiwan, which is the second-longest freeway tunnel (12.9 km) in Asia. This endeavor aims to characterize the chemical constituents and size distributions, as well as fingerprinting ratios of particulate metals emitted by vehicle fleets. A total of 36 metals in size-resolved aerosols were determined through inductively coupled plasma mass spectrometry. Three major groups - namely, tailpipe emissions (Zn, Pb, and V in fine mode), wear debris (Cu, Cd, Fe, Ga, Mn, Mo, Sb, and Sn), and resuspended dust (Ca, Mg, K, and Rb) - of airborne PM metals were categorized on the basis of the results of enrichment factor, correlation matrix, and principal component analysis. Size distributions of wear-originated metals resembled the pattern of crustal elements, which were predominated by super-micron particulates (PM1-10). By contrast, tailpipe exhaust elements such as Zn, Pb, and V were distributed mainly in submicron particles. By employing Cu as a tracer of wear abrasion, several inter-metal ratios - including Fe / Cu (14), Ba / Cu (1.05), Sb / Cu (0.16), Sn / Cu (0.10), and Ga / Cu (0.03) - served as fingerprints for wear debris. However, the data set collected in this work is useful for further studies on traffic emission inventory and human health effects of traffic-related PM.
Effects of high shear rate shearing on material structure and mechanical property of iPP/PC blends
(2008-02-01)
Lu, M. -C.
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Chen, R. -H.
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Chi, K. -H.
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機械工程學系
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Department of Mechanical Engineering
Polycarbonate (PC) and crystalline polymer, isotatic polypropylene (iPP), are extruded using a mechanical blending extruder and a reciprocated mechanism for shearing is designed to perform long term shearing at a high shear rate in the packing stage. The present work investigates the effects of high shear rate shearing on the orientation of the phase morphologies and mechanical properties. The experiment utilises the technologies of specimen preparation and observation to examine the change in phase morphology. Additionally, the mechanical properties of injection moulded specimens under different processing conditions are measured. Experimental results show that adding a little PC into the iPP matrix, less than around 20%, increases the tensile strength of specimens. The orientation of the phase is improved and most of the tensile strength of the blends is increased after shearing. The tensile strength of the shearing specimens with a PC content of,25% exceeds that of the normal specimens of pure iPP. A higher iPP content corresponds to a higher tensile strength after shearing. This investigation also considers the possibility of using iPP/PC blends in industrial applications, indicating that shearing is valuable in industrial applications when the PC content in iPP/PC blends is 25%.