Materials Science and Engineering Commons^™

Degradation Mechanism Of Expanded Polystyrene (Eps) Foam In Lost Foam Casting, Pips Approach For Synthesis And Novel Expansion Techniques For Cellular Foam, Indraneel Sen

Doctoral Dissertations

Lost Foam Casting (LFC) is a metal casting technology that facilitates fabrication of near-net shape metal castings using expanded polystyrene (EPS) foam patterns that are coated with refractory slurry and is effective for producing aluminum or iron castings of complicated geometry. However, the LFC process can produce considerable amount of scrap due to casting defects. Removing the EPS thermal decomposition products through the ceramic coating ahead of the advancing metal front during the liquid metal pour is a key factor in obtaining a defect free casting. Developing a fundamental understanding of foam degradation mechanism is essential in improving LFC process. …

Chemical Characterization Of Pan Based Carbon Fibers Produced By Microwave Assisted Plasma (Map) Technology And Effect Of Plasma Treatment On Carbon Fiber Surface And Interphase With Polymer Matrix, Xiaoyu Luo

Doctoral Dissertations

The first objective of this research was to chemically characterize the surface of conventional carbon fiber and carbon fiber produced by microwave assisted plasma (MAP) manufacturing process. The chemical composition and functional groups on the surface of the fibers were determined by X-ray photoelectron spectroscopy (XPS). The untreated unsized MAP carbon fibers were compared to untreated unsized conventional carbon fibers and showed a significant amount of oxygen. Comparison between treated unsized MAP carbon fiber and treated unsized conventional carbon fiber reveal a 100% enhancement of oxygen elemental concentration.

Two plasma systems, remote applicator and atmospheric plasma were used to treat …

Thermal And X-Ray Analysis On The Origin Of Double Melting Phenomena Of Poly(L-Lactic Acid) Films, Xiaoyun Ling

Doctoral Dissertations

Thermal analysis is one of the most commonly used techniques to characterize the structure and properties of semicrystalline polymers. Unfortunately, the interpretation of thermal events is not always straightforward, but can be quite complicated. However, the complexity involved is often overlooked, leading to erroneous or, at least, questionable results and interpretations. In the present study we carry out an extensive investigation of the thermal behavior of poly(L-lactic acid), PLLA, films prepared under a wide range of crystallization conditions, including isothermal and non-isothermal crystallization from both the glassy state and the melt. The primary techniques used were differential scanning calorimetry (DSC), …