Study of the effect on conductivity and its uniform distribution in injection molded composite polymer bipolar plate

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Chen Shia-Chung ◽  
Shih Ming-Yi ◽  
Lin Yi-Chang
Keyword(s):  
Flow Direction ◽  
Mold Temperature ◽  
Bipolar Plate ◽  
Surface Conductivity ◽  
Temperature Control System ◽  
Melt Flow ◽  
Molded Part ◽  
Molded Parts ◽  
Fluid Channel ◽  
Injection Molded

AbstractIn this study, PPS blended with as high as 50 wt% carbon fiber were injection molded. Effects of molding conditions as well as the melt flow condition parallel and perpendicular to fluid channel on the surface conductivity was investigated. It was found that mold temperature affects the surface conductivity of molded parts significantly. Using a variable mold temperature control system based on electromagnetic induction heating, the conductivity of the molded part increase by about 152% when the peak mold temperature increases from 120 °C to 210 °C. The channel layout also helps the fiber to orient more randomly leading to an increase in the conductivity. The channel design parallel to melt flow increases the conductivity by 152% and when it is perpendicular to melt flow, the conductivity increases by 95%. Channel layout perpendicular to melt flow direction provides more influence on the fiber reorientation than that of the parallel design.

Warpage Characterization of Thin and Centrally-Gated Injection Molded Part by Applying Cavity Pressure Measurement

2013 ◽  
Vol 446-447 ◽  
pp. 1099-1103 ◽  
Author(s):  
H. Zamani ◽  
S. Azmoudeh ◽  
K. Shelesh-Nezhad
Keyword(s):  
Radial Flow ◽  
Mold Temperature ◽  
Cavity Pressure ◽  
Injection Speed ◽  
Molded Part ◽  
Pressure Time ◽  
Molded Parts ◽  
Injection Molded ◽  
Thin Disks

Two types of injection molded parts including parts with thin shell feature and parts molded with radial flow pattern are highly susceptible to the warpage. In this research, the warpage performance of a thin and centrally-gated disk was experimentally investigated. The melt pressure-time traces of two different locations inside the mold cavity were monitored by employing piezoelectric transducers. The results indicated that the pressure difference magnitude of melt at two locations along the radial flow path is related to the extent of molded part deformation. Moreover, it was pointed out that the high magnitude of warpage is because of two conflicting actions in the molded part comprising expansion as a result of viscoelastic recovery in the central region, and thermal contraction in the edge region of the thin disk. The molding variables encompassing injection speed, holding pressure, back pressure, mold temperature and screw rotational speed affected the thin disks deformation in order of significance.

Viscoelasticity Effects of Polymeric Material in Micro Injection Molding

2008 ◽  
Author(s):  
Peiman Mosaddegh ◽  
David C. Angstadt
Keyword(s):  
Oscillation Mode ◽  
Polymeric Materials ◽  
Elastic Response ◽  
Cavity Pressure ◽  
Molded Part ◽  
Molded Parts ◽  
Filling Phase ◽  
Injection Molded ◽  
Poly Ethylene ◽  
Peak Value

An experimental study has been carried out to determine the effect of viscoelasticity in comparison to viscosity on micro-injection molded parts. In this study, two different polymeric materials — Polystyrene (PS) as a viscous material and High Density Poly-Ethylene (HDPE) as a viscoelastic material — have been selected to observe the effect of melt elasticity on the filling phase of micro molding based on cavity pressure of molded part. All process parameters except temperature are the same for both polymers. Process temperatures have been selected in order to match the viscosity for both polymers used. Polymer viscosity was characterized at different shear rate and temperature. Viscoelasticity of both polymers were investigated using rotational rheometry in the oscillation mode. The mold geometry with high aspect ratio has been used and the effect of viscoelasticity on cavity pressure has been discussed. It was observed that there is retardation on the response of pressure because of elastic response of material during filling. Despite the differences in slope, peak value, area, and cycle time between two curves, they share similar trends. The only difference is their response during solidifying because of material property.

Effect of Size and Spatial Distribution of Titania Pigments in Injection Molded Parts on Surface Reflectance

2007 ◽  
Author(s):  
B. R. Dantal ◽  
A. Saigal ◽  
M. A. Zimmerman
Keyword(s):  
Spatial Distribution ◽  
Statistical Significance ◽  
Average Diameter ◽  
Area Fraction ◽  
Light Emitting ◽  
Molded Part ◽  
Molded Parts ◽  
Injection Molded ◽  
The Difference ◽  
New Applications

Titania pigments are used in molding compounds as a means to improve opacity by increasing the scattering efficiency of the medium and to develop new applications such as liquid crystal displays (LCD) and light emitting diodes (LED). The characteristics of the injection molded products are a function of molding parameters such as gate location and shear rate. In this study, quantitative measures of the particle distribution of titania pigments in polymer composites have been experimentally determined, including area fraction, average diameter, and diameter volume. A 2 × 3 × 3 ANOVA test has been conducted to assess the statistical significance of these parameters. This study deals with the size and spatial distribution of the particles. The important parameters calculated based on the Feret’s diameter are diameter-volume (dv), diameter-number (dn), and area fraction (AF). The term diameter-volume (dv) has been used to give greater significance to the large particles and thus ‘large’ indicates more and/or larger particles. The parameters have been calculated by using Image-J image processing software. MINITAB has been used to assess the statistical significance of these parameters. The results show that titania particles are not uniformly distributed within the final molded parts and they vary along the molding (longitudinal) and transverse directions of plastic flow. The difference of pigment area fraction and diameter volume at different locations within a final molded part has a significant effect on the percentage reflectance of the surface.

scholarly journals Optimization and application of temperature field in rapid heat cycling molding

2021 ◽  
pp. 291-291
Author(s):  
Mingliang Hao ◽  
Haimei Li
Keyword(s):  
Injection Molding ◽  
Electric Heating ◽  
Heating System ◽  
Mold Temperature ◽  
Temperature Control System ◽  
Cavity Surface ◽  
Injection Mold ◽  
Molding Process ◽  
Molded Parts ◽  
Automotive Part

The rapid thermal cycle molding (RHCM) belongs to the injection mold temperature control system which is helpful to improve mold ability and enhance part quality. Despite many available literatures, RHCM does not represent a well-developed area of practice. The challenge is the uneven distribution of temperature in the cavity after heating, which mostly leads to defects on the surface of the products. In order to obtain uniform cavity surface temperature distribution of RHCM, the power of heating rods of the electric-heating system in an injection mold was optimized by the response surface method(RSM) in this work. The proposed optimization result was applied to design a complex RHCM injection mold with side core-pulling, holes and different thickness of an automotive part to verify its effectiveness by injection molding. Compared with initial design, the mold temperature uniformity was remarkably improvedby79%. Based on the optimization and injection molding numerical simulation results, the workable molding process to weaken the weld-lines effects on the quality was suggested and the practical injection molded parts were well produced.

Fiber Orientation in Injection-Compression Molded Short-Fiber-Reinforced Polypropylene Parts

2009 ◽  
Author(s):  
Han-Xiong Huang ◽  
Can Yang ◽  
Kun Li
Keyword(s):  
Fiber Orientation ◽  
Flow Direction ◽  
Processing Parameters ◽  
Short Fiber ◽  
Fiber Reinforced ◽  
Compression Force ◽  
Time Compression ◽  
Compression Time ◽  
Molded Parts ◽  
Injection Molded

Four processing parameters, including compression force, compression time, compression distance, and delay time, were investigated in terms of their effects on the fiber orientation in injection-compression molded (ICM) short-fiber-reinforced polypropylene parts. The results reveal that the fiber orientation pattern in ICM parts is different from that in conventional injection molded parts. Compression force plays an important role in determining the fiber orientation, whereas the effect of compression time can be neglected. Moreover, the fiber orientation changes obviously in the width direction, with most fibers arranging orderly in the flow direction at positions near the mold cavity wall.

The skin-core morphology of injection-molded syndiotactic polystyrene

1990 ◽  
Vol 48 (4) ◽  
pp. 1096-1097
Author(s):  
R.C. Cieslinski ◽  
L.C. Lopez ◽  
R.D. Wesson
Keyword(s):  
Mold Temperature ◽  
Syndiotactic Polystyrene ◽  
Molded Part ◽  
Transmission Electron ◽  
Structural Differences ◽  
Two Temperatures ◽  
Injection Molded ◽  
Point To Point ◽  
Polymer Mold ◽  
Surface Figure

Injection molding is an important fabrication process for the molding of thermoplastics. It is generally recognized that the final properties of the injection molded part are strongly dependent upon morphology, orientation, and stress. These effects are particularly evident in a semicrystalline polymer such as syndiotactic polystyrene where the melt orientation and cooling rates can vary appreciably from point to point within the mold cavity leading to pronounced morphological and crystallinity inhomogeneities.This paper describes the effects of polymer mold temperature on the overall morphology of syndiotactic polystyrene in an injection molded tensile bar specimen. The morphology was examined in samples molded at 50°C and 160°C using polarized optical microscopy, transmission electron microscopy, and Fourier transform infrared micro-spectroscopy.A skin-core effect was found and significant structural differences existed in the skins of the samples molded at the two temperatures. Bars molded at 50°C had a shish kebab morphology at the surface (Figure 1)

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