Filtering by
- All Subjects: Energy Absorption
- All Subjects: chemical engineering
- Creators: Zhuang, Houlong
MFI zeolite membranes were synthesized on α-alumina supports by secondary growth method. Novel positron annihilation spectroscopy (PAS) techniques were used to non-destructively characterize the pore structure of these membranes. PAS reveals a bimodal pore structure consisting of intracrystalline zeolitic micropores of ~0.6 nm in diameter and irregular intercrystalline micropores of 1.4 to 1.8 nm in size for the membranes. The template-free synthesized membrane exhibited a high permeance but a low selectivity in C3H6/C3H8 mixture separation.
CMS membranes were synthesized by coating/pyrolysis method on mesoporous γ-alumina support. Such supports allow coating of thin, high-quality polymer films and subsequent CMS membranes with no infiltration into support pores. The CMS membranes show strong molecular sieving effect, offering a high C3H6/C3H8 mixture selectivity of ~30. Reduction in membrane thickness from 500 nm to 300 nm causes an increase in C3H8 permeance and He/N2 selectivity, but a decrease in the permeance of He, N2 and C3H6 and C3H6/C3H8 selectivity. This can be explained by the thickness dependent chain mobility of the polymer film resulting in final carbon membrane of reduced pore size with different effects on transport of gas of different sizes, including possible closure of C3H6-accessible micropores.
CMS membranes demonstrate excellent C3H6/C3H8 separation performance over a wide range of feed pressure, composition and operation temperature. No plasticization was observed at a feed pressure up to 100 psi. The permeation and separation is mainly controlled by diffusion instead of adsorption. CMS membrane experienced a decline in permeance, and an increase in selectivity over time under on-stream C3H6/C3H8 separation. This aging behavior is due to the reduction in effective pore size and porosity caused by oxygen chemisorption and physical aging of the membrane structure.
The goal of this experiment was to examine the energy absorption properties of origami-inspired honeycomb and standard honeycomb structures. These structures were 3D printed with two different materials: thermoplastic polyurethane (TPU) and acrylonitrile butadiene styrene (ABS). Quasi-static compression testing was performed on these structures for both types and materials at various wall thicknesses. The energy absorption and other material properties were analyzed for each structure. Overall, the results indicate that origami-inspired structures perform best at energy absorption at a higher wall thickness with a rigid material. The results also indicated that standard honeycomb structures perform better with lower wall thickness, and also perform better with a rigid, rather than a flexible material. Additionally, it was observed that a flexible material, like TPU, better demonstrates the folding and recovery properties of origami-inspired structures. The results of this experiment have applications wherever honeycomb structures are used, mostly on aircraft and spacecraft. In vehicles with structures of a sufficiently high wall thickness with a rigid material, origami-inspired honeycomb structures could be used instead of current honeycomb structures in order to better protect the passengers or payload through improved energy absorption.