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The Effect Of Non-Newtonian Rheology On Gas-Assisted Injection Molding Process

Wang, Yijie
http://rave.ohiolink.edu/etdc/view?acc_num=osu1053622915

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Chemical Engineering.
The process of less viscous fluid penetrating through viscous fluid in simple geometry has practical application in gas-assisted injection molding technology (GIM or GAIM). A Hele-Shaw cell geometry was employed to study the process of gas penetration through Newtonian, pure viscoelastic and shear thinning fluids. Hele-Shaw cells with different width to height ratio were employed in the experiment and the data of fractional coverage as function of cap illary number was collapsed by considering the geometrical effect in the modified capillary number. Also the dependence of bubble stability on fluid rheology, bubble velocity and geometry was studied. The viscoelasticity tends to distabilize the finger while shear thinning has stabilizing effect. The effect of temperature gradient on the process was studied by injecting gas bubble through Newtonian fluid in capillary tube under non-isothermal condition. The final resin thickness on the tube’s inner wall is a complex function of melt rheology, mold design and processing conditions. Two specific Newtonian fluids with flow activation energies of 7324.7 K and 1090.4 K were chosen and their rheological characteristics were analyzed. Isothermal and non-isothermal experiments were performed in simple tube geometry. A coating was formed by filling the tube with a polymer and then injecting the gas through the tube. Results showed that the fractional coverage passes through a maximum and then gradually approaches the isothermal value at very long delay times. The results were explained based on radial temperature and velocity profiles. The fractional coverage was found to be a strong function of fourier number and capillary number. A Frozen Layer model was set up to predict the fractional coverage as function of delay time and the calculated values agreed well with the experimental data. Three characterized highly shear thinning Carbopol water solutions were tested in gas/oil assisted injection process. The dependence of coating layer thickness on the degree of shear thinning, bubble viscosity, geometry was studied experimentally. Simulation was done based on measured bubble profiles by fixing bubble position and shape in the mesh setup and assuming full slip along the interface. The simulation method was tested based on previous experimental result.
Kurt Koelling (Advisor)
Engineering, Chemical
Gas-assisted injection molding; Non-Newtonian flow; interface; bubble penetration

Recommended Citations

Citations

  • Wang, Y. (2003). The Effect Of Non-Newtonian Rheology On Gas-Assisted Injection Molding Process [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1053622915

    APA Style (7th edition)

  • Wang, Yijie. The Effect Of Non-Newtonian Rheology On Gas-Assisted Injection Molding Process. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1053622915.

    MLA Style (8th edition)

  • Wang, Yijie. "The Effect Of Non-Newtonian Rheology On Gas-Assisted Injection Molding Process." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1053622915

    Chicago Manual of Style (17th edition)

osu1053622915
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© 2003, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.