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Project No Drip Final update Presentation

This project provides updates on density data of LDPE and HDPE plastics, shear tests using plastic bags, remolding of plastic, and modeling of heat conduction during the joining process. Future plans include DSC or DMA testing on plastic bags, building a final working prototype, and completing modeling work and illustrations.

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Project No Drip Final update Presentation

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  1. Project No DripFinal update Presentation Jacqueline Greene Michele Dufalla Tania Chan May 3, 2007

  2. Main updates • Density data of LDPE and HDPE plastics • Final shear instron tests using plastic bags • Remolding of plastic • Modeling of heat conduction during joining process • Future plans

  3. Density Data • Measured the mass of the following plastics: black LDPE, clear LDPE, LDPE campus convenience bag, LDPE Coop bag, LDPE McMaster sheet, HDPE McMaster sheets • LDPE average density (n=5) = 0.95 ± 0.27 g/cm^3 • HDPE average density(n=4) =0.96 ± 0.04 g/cm^3 • Data online: LDPE density= 0.923 (g/cm3) HDPE density=0.954 g/cm3 • Khonakdar, H.A. et al. Effect of electron-irradiation on cross-link density and crystalline structure of low- and high-density polyethylene. Radiation Physics and Chemistry. Vol 75(1) Jan. 2006: 78-86.

  4. Shear Tests

  5. Shear Tests

  6. Governing equation: • = density, k = thermal conductivity, c = specific heat, s = heat generation Constant Heat Flux (q) x = 0 Semi Infinite Solid Polyethylene x Modeling Heat Conduction in HDPE Boundary Conditions: At t = 0: T = T0 = 25oC At x = 0: q At x = ∞: T|x = ∞ = T0 = 25oC S = 0, no heat generation

  7. Modeling Heat Conduction in HDPE Modified Governing Equation: Thermal Diffusivity: (Materials Parameter) • Governing equation can be solved mathematically by Fourier series, Green’s function • Simplest computational model is Finite Differences

  8. Modeling Heat Conduction: Finite Differences and time is temperature at position Discretizing space and time: Temperature Derivative Estimate: Second Derivative Approximations:

  9. Finite Differences: 1-D Conduction Modeling Modified Governing Equation: Finite Differences Approximations:

  10. Reptation: Polymer Diffusion in Melts Polymer-polymer interdiffusion at an interface proceeds in two stages • At time shorter than reptation time, the diffusion process is explained by the reptation model • At time great than reptation time, the diffusion process can be explained by continuum theories, Fick’s Law

  11. Short Time Scale: Reptation Model Polymer chain confined within a “tube” defined by neighboring chains Movement of chain limited to along the chain axis Entanglement prevents the polymer chains from crossing the interface, chain ends near the interface dominate movement Diffusion can be scaled with the distance a chain takes to move out of the constraining “tube” cbp.tnw.utwente.nl/PolymeerDictaat/node62.html http://wwwcp.tphys.uni-heidelberg.de/Polymer/day3/p3-1.htm

  12. Time Regimes in Reptation Model 1/2 1/4 1/8 1/4 • Below e: Chain feels the effects of its own connectivity but no the entanglement (wt1/4) • Between e and r: Motion perpendicular to the tube is constrained • Between r and R: Motion parallel to the tube occurs, but dominated by the constraining of the tube • Above R: Chain moves out of tube, Fick’s Law dominates At t< Interfacial width increases at t1/4 Log w(t) wt1/8 wt1/4 wt1/2 wt1/4 log t

  13. Long Time Scale: Fickian Diffusion • At t> , polymer interface diffusion is a Fickian process Fick’s First Law: Fick’s Second Law: Diffusion scales: wt1/2

  14. Final Plans • DSC or DMA testing on plastic bag • Build final working prototype, using a real jerry can • Complete modeling work and illustrations

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