A melt flow indexer (MFI) was used to investigate high-temperature transitions in melts of high-density polyethylene (HDPE). The MFI data were obtained in the range 190–230°C. These transitions were found in the MFI at about 210 and 225°C and reproduced in a Haake melt blender. Polystyrene was used in the blender experiment to demonstrate typical amorphous behavior. For HDPE melts, the MFI–temp...

This work presents new results on using organoclay with an appropriate polymeric compatibilizer as rheology-modifying additives for extrusion foaming of a linear polypropylene (PP), which by itself does not display strain hardening in extensional flow of the melt. The uniaxial melt-extensional viscosity behavior of several nanocomposites prepared with varying ratio of bound maleic anhydride to ...

In this work, rheological properties of poly(lactic acid) (PLA), low density polyethylene (LDPE) polymer blends were investigated in the molten state. The experiments were carried on a capillary rheometer. The effect of shear stress, temperature and blending ratio on the flow activation energy at a constant shear stress and melt viscosity of the blends are described. The results showed that the...

By application of optical coherence tomography (OCT), an interferometric noncontact imaging technique, the crystallization of a supercooled poly(propylene) melt in a slit die is monitored. Both the quiescent and the sheared melt are investigated, with a focus on experiments where solidification and flow occur simultaneously. OCT is found to be an excellent tool for that purpose since the result...

A novel diffuse interface model is presented for the direct numerical simulation of microstructure evolution in solidification processes involving convection in the liquid phase. The solidification front is treated as a moving interface in the diffuse approximation as known from phase-field theories. The no-slip condition between the melt and the solid is realized via a drag resistivity in the ...

The axisymmetric flows with swirl or rotation were solved by a hybrid scheme with lattice Boltzmann method for the axial and radial velocities and finite-difference method for the azimuthal (or swirl) velocity and the temperature. An incompressible axisymmetric lattice Boltzmann D2Q9 model was proposed to solve the axial and radial velocities through inserting source terms into the two-dimensio...

Permeability and meltwater flow have been studied in sea ice in the Siberian and central Arctic during the summers of 1995 and 1996. A bail-test technique has been adapted to allow for measurements of in situ permeability, found to range between 10 and 10 m. Permeability varied by about a factor of 2 between 1995 (above-normalmelt rates) and1996 (below-normalmelt rates). Release of fluorescent ...

Meltwater discharge and electrical conductivity were measured in eight 1 3 1 m lysimeters, and snow accumulation and electrical conductivity of melted samples were measured in snow pits during four snowmelt seasons at Mammoth Mountain, California. The peak snow-water equivalent ranged from 0.57 to 2.92 m over the four melt seasons. Lysimeter discharges ranged from 20% to 205% of the mean flow; ...