Effects of Polymer Morphology on the Rheological Behavior of Melt Within Micro-Channels

2008 ◽  
Author(s):  
Shia-Chung Chen ◽  
Rean-Der Chien ◽  
Song-Wei Huang ◽  
Chun-Sheng Chen
Keyword(s):  
Rheological Behavior ◽  
Polymer Melt ◽  
Degree Of Crystallinity ◽  
Micro Channel ◽  
Melt Temperature ◽  
Channel Size ◽  
High Crystallinity ◽  
Micro Channels ◽  
Micro Molding ◽  
Low Crystallinity

Micro molding has shown great commercial potential in recent years and determination of the rheological behavior of the polymer melt within micro structured geometry is vital for accurate simulation modeling of micro molding. The lack of commercial equipment is one of main hurdles in the investigation of micro melt rheology. In this study, a melt viscosity measurement system for low and high density polyethylene polymer melt flowing through micro-channels was established using a micro channel mold operated at a mold temperature as high as the melt temperature. For measured pressure drop and volumetric flow rate, capillary flow model was used for the calculation of viscosity utilizing Rabinowitsch correction. The calculated results of low crystallinity LDPE resin were also compared with those of high crystallinity HDPE resin to discuss the effect of degree of crystallinity on the viscosity characteristics of polymer within micro-channels. It was found that the measured LDPE and HDPE viscosity values in the test ranges are significantly lower (about 40∼56% and 22∼29% for LDPE and HDPE, respectively, flowing through a channel size of 150μm) than those obtained with a traditional capillary rheometer. Meanwhile, the percentage reduction in the viscosity value and the ratio of slip velocity relative to mean velocity all increase with decreasing micro-channel size. In the present study we emphasize that the rheological behavior of the high crystallinity HDPE and low crystallinity LDPE resins in microscopic scale are all different from that of macroscopic scale but HDPE displays a less significant lower. The reason can be attributed to for LDPE resin within the micro-channel can create the higher extra bonding force between the bulk chains than HDPE resin. Thus, it will have the lower adhesive force between the bulk chains with the micro-channel wall, resulting in higher degree of wall slip.

Rheological Behavior of Polymethyl Methacrylate (PMMA) Filling through Micro Channels

2011 ◽  
Vol 189-193 ◽  
pp. 451-454 ◽  
Author(s):  
Bin Xu ◽  
Yu Bin Lu ◽  
Guang Ming Li ◽  
Song Xue ◽  
Bei Ping Xiang
Keyword(s):  
Polymethyl Methacrylate ◽  
Rheological Behavior ◽  
Capillary Flow ◽  
Rapid Development ◽  
Polymer Melt ◽  
Characteristic Size ◽  
Micro Channel ◽  
Channel Characteristic ◽  
Micro Channels ◽  
The Difference

With the rapid development of micro injection molding, the determination of melt rheological behavior within micro mold cavity is very important for the accurate simulation modeling. Yet several investigations show the viscosity of melt decreases with the reduction of micro channel characteristic size, but there has been no sufficient experimental data for the conclusion. In this paper, depending on the capillary flow model, the measurement experiments of polymer melt viscosity were investigated when Polymethyl Methacrylate (PMMA) was extruded through the micro channel dies of 1000μm ,500μm and 350μm diameter. Test results show that, as micro-channel size decreases, the viscosity increases and the difference of viscosities in different micro channels reduces with increasing shear rate. This indicates microscopic scale melt rheological behavior of PMMA is different from that of other materials.

Experimental Research on the Viscosity of Polymer Melts Filling through Micro Channels

2011 ◽  
Vol 314-316 ◽  
pp. 1346-1349
Author(s):  
Bin Xu ◽  
Yu Bin Lu ◽  
Guang Ming Li ◽  
Song Xue
Keyword(s):  
Shear Rate ◽  
Flow Model ◽  
Capillary Flow ◽  
Polymer Melt ◽  
Characteristic Size ◽  
Micro Channel ◽  
Test Results ◽  
Micro Channels ◽  
Rate Test ◽  
The Difference

Experimental observations indicate that the viscosity of polymer melt flowing through micro channel is altered with variation of characteristic size of micro channels. The explanation about the trend of various viscosity is inconsistent. In this paper, the micro channel dies of 1000μm ,500μm and 350μm diameter were developed and with several polymers, including PP , PS and HDPE, depending on the capillary flow model, the measurement experiments of polymer melt viscosity were investigated at various shear rate. Test results show that with micro-channel size decrease, the percentage reduction in viscosity increases and the difference of viscosities in different micro channels reduces with increasing shear rate.

Experimental Study on Viscous Dissipaition of Polymer Melt in Micro-Channels

2010 ◽  
Vol 97-101 ◽  
pp. 2527-2532 ◽  
Author(s):  
Tong Min Yu ◽  
Hai Xin Bei ◽  
Ze Yu Yan ◽  
Bin Xu ◽  
Hua Xu ◽  
...  
Keyword(s):  
Shear Rate ◽  
Viscous Dissipation ◽  
Amorphous Polymer ◽  
Polymer Melt ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Micro Channel ◽  
Aspect Ratios ◽  
Micro Channels ◽  
Macro Scale

The polymer melts viscous dissipation effects of micro scale dimensions are different from that of macro-scale dimensions. In this paper, the temperature rises due to viscous dissipation were investigated when amorphous polymer material, PMMA, flows through several micro-channels with the diameters of 350μm, 500μm and different aspect ratios. The results indicate that, temperature rises reduce with the increase of inlet temperature of melt and increase with increasing channel’s diameter and aspect ratio at the same shear rate. The outlet temperature rises due to viscous dissipation in all micro channels increase with the increase of shear rate. In addition, the outlet temperature rise grows faster with the decrease of micro-channel’s diameter. Therefore, viscous dissipation effect is significant and should not be neglected in micro channel.

Rheological behaviour of low/high density polyethylene melt flowing through micro-channels

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Chun-Sheng Chen
Keyword(s):  
High Density Polyethylene ◽  
Capillary Flow ◽  
Rheological Behaviour ◽  
Polymer Melt ◽  
Volumetric Flow Rate ◽  
Wall Slip ◽  
High Density ◽  
Mean Velocity ◽  
Channel Size ◽  
Micro Channels

AbstractThe determination of the proper rheological behaviour of the polymer melt within micro structured geometry is vital for accurately simulating the micro moulding. The paucity of suitable equipments is one of main hurdles in the investigation of micro melt rheology. In the present study, a measurement system for the melt viscosity of low and high density polyethylene polymer melts flowing through micro-channels was established. The capillary flow model with Rabinowitsch correction was used in the calculations of the viscosity based on the measured pressure drop and volumetric flow rate. The effect of the morphology structure on the viscosity characteristics for both the LDPE and HDPE resins within micro-channels was investigated and discussed. It was found that the measured viscosity values for LDPE and HDPE in the test ranges are significantly lower (about 40~56% and 22~29% for LDPE and HDPE, respectively, flowing through a channel size of 150μm) than those obtained with a traditional capillary rheometer. Moreover, both the percentage reduction in the viscosity value and the ratio of the slip velocity to the mean velocity increase as the micro-channel size decreases. It can be observed that the rheological behaviours of the HDPE and LDPE resins in microscopic scale are different from those in macroscopic scale as a result of the wall slip effect. It also revealed that the wall slip occurs more easily for the LDPE resin within micro channels than HDPE resin due to enlarged effect of morphology structure.

Rheological behavior of POM polymer melt flowing through micro-channels

2008 ◽  
Vol 44 (6) ◽  
pp. 1891-1898 ◽  
Author(s):  
Chun-Sheng Chen ◽  
Shia-Chung Chen ◽  
Wei-Lianq Liaw ◽  
Rean-Der Chien
Keyword(s):  
Rheological Behavior ◽  
Polymer Melt ◽  
Micro Channels

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Effect of Crystallographic Quality of Grain Boundaries on Both Mechanical and Electrical Properties of Electroplated Copper Thin Film Interconnections

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Naokazu Murata ◽  
Naoki Saito ◽  
Kinji Tamakawa ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Electrical Properties ◽  
Grain Boundaries ◽  
Fatigue Fracture ◽  
High Crystallinity ◽  
Mechanical And Electrical Properties ◽  
Copper Interconnection ◽  
Electroplated Copper ◽  
Two Parameters ◽  
Low Crystallinity

Effects of crystallographic quality of grain boundaries on mechanical and electrical properties were investigated experimentally. A novel method using two parameters of image quality (IQ) and confidence index (CI) values based on electron back-scattering diffraction (EBSD) analysis was proposed in order to evaluate crystallographic quality of grain boundaries. IQ value was defined as an index to evaluate crystallinity in region irradiated with electron beam. CI value determined existence of grain boundaries in the region. It was found that brittle intergranular fatigue fracture occurred in the film without annealing and the film annealed at 200 °C because network of grain boundaries with low crystallinity remained in these films. On the other hand, the film annealed at 400 °C caused only ductile transgranular fatigue fracture because grain boundaries with low crystallinity almost disappeared. From results of measurement of electrical properties, electrical resistivity of copper interconnection annealed at 400 °C with high crystallinity (2.09 × 10−8 Ωm) was low and electron migration (EM) resistance was high compared with an copper interconnection without annealing with low crystallinity (3.33 × 10−8 Ωm). It was clarified that the interconnection with high crystallinity had superior electrical properties. Thus, it was clarified that the crystallographic quality of grain boundaries has a strong correlation of mechanical and electrical reliability.

Flow Characteristics of Pressure-Driven Water in Serpentine Micro-Channels

2006 ◽  
Author(s):  
Renqiang Xiong ◽  
J. N. Chung
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Flow Characteristics ◽  
Flow Structures ◽  
Micro Channel ◽  
Pressure Drops ◽  
Micro Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Micro Channels ◽  
Shape And Size

Flow structures and pressure drops were investigated in rectangular serpentine micro-channels with miter bends which had hydraulic diameters of 0.209mm, 0.395mm and 0.549mm respectively. To evaluate the bend effect, the additional pressure drop due to the miter bend must be obtained. Three groups of micro-channels were fabricated to remove the inlet and outlet losses. A validated micro-particle image velocimetry (μPIV) system was used to achieve the flow structure in a serpentine micro-channel with hydraulic diameter of 0.173mm. The experimental results show the vortices around the outer and inner walls of the bend do not form when Re<100. Those vortices appear and continue to develop with the Re number when Re> 100-300, and the shape and size of the vortices almost remain constant when Re>1000. The bend loss coefficient Kb was observed to be related with the Re number when Re<100, with the Re number and channel size when Re>100. It almost keeps constant and changes in the range of ± 10% When Re is larger than some value in 1300-1500. And a size effect on Kb was also observed.

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