Interface Slippage Study Between Polyamide 12 and Ethylene Butene Copolymer Melt In Capillary Extrusion

Extrusion of a polyamide 12 (PA12) material through a capillary die coated with an ethylene butene copolymer (EBM) was studied. The EBM coated die significantly increased the flow rates of the PA12 melt compared to a clean die at the same extrusion pressure. Introducing a maleic anhydride grafted ethylene-octene copolymer (EOM-g-MAH) into the EBM suppressed the effect. This behavior seems only explained by significant interface slippage between PA12 and EBM melts, which could be eliminated by introducing covalent chemical bonds across the interface. A mathematical analysis was carried out to calculate the interface slippage. The shear stress where slippage began to occur was around 0.045 MPa and the slippage velocity was around 15 mm/s at 0.1 MPa. Adding EOM-g-MAH could largely decrease the interfacial tension between EBM and PA12, thus largely decrease the interface slippage. (C) 2009 The Society of Rheology [DOI: 10.1122/1.3198245

Subsurface Carbon Dioxide Sequestration and Storage in Methane Hydrate Reservoirs Combined With clean Methane Energy Recovery

The authors gratefully acknowledge the financial support (2003-2005) received from the Scottish Higher Education Funding Council. Thanks to Mr. Jim Pantling for construction and maintenance of the experimental equipment. Prashant Jadhawar thanks the Institute of Petroleum Engineering and the Centre for Gas Hydrate Research for financial support. Useful comments from Ross Anderson and Rod Burgass are also gratefully acknowledged.Peer reviewedPostprin

Insights into the climate-driven evolution of gas hydrate-bearing permafrost sediments: implications for prediction of environmental impacts and security of energy in cold regions

The present study investigates the evolution of gas hydrate-bearing permafrost sediments against the environmental temperature change. The elastic wave velocities and effective thermal conductivity (ETC) of simulated gas hydrate-bearing sediment samples were measured at a typical range of temperature in permafrost and wide range of hydrate saturation. The experimental results reveal the influence of several complex and interdependent pore-scale factors on the elastic wave velocities and ETC. It was observed that the geophysical and geothermal properties of the system are essentially governed by the thermal state, saturation and more significantly, pore-scale distribution of the co-existing phases. In particular, unfrozen water content substantially controls the heat transfer at sub-zero temperatures close to the freezing point. A conceptual pore-scale model was also proposed to describe the pore-scale distribution of each phase in a typical gas hydrate-bearing permafrost sediment. This study underpins necessity of distinguishing ice from gas hydrates in frozen sediments, and its outcome is essential to be considered not only for development of large-scale permafrost monitoring systems, bus also accurate quantification of natural gas hydrate as a potential sustainable energy resource in cold regions