Using Electron Microscopy to Investigate Degradation of Candidate PEM Membranes due to Exposure to Fenton¡¦s Reagent

Abstract

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Morphology and thermal expansion in large HDPE injection moldings

“…Weakley-Bollin found the skin thickness of his injection molded parts to be in the range of 2-10 μm. 8 Wang et al found the skin layer on injection molded polyolefin samples to be in the order of 10-50 μm for the processing conditions tested in their investigation. 11 However, Jansen reported the thickness of the skin layer to be in the range of 95-530 μm, depending on the resin flow rate during molding; a higher flow velocity corresponds to a lower skin thickness.…”

“…Some studies found that LCTE did not appear to be significantly affected by the measurement direction relative to resin flow, or location of the sample in respect to the injection gate. 3,8 On the other hand, another study did find that the LCTE for injection molded parts varied to some degree between the flow and transverse to flow directions, and that the thermal expansion for samples collected at the halfway point of the flow path appeared slightly larger than those collected near the gate or at the end of flow. 2 Zhang et al found the same to be true in his study on polyolefin blends.…”

“…Injection molding results in anisotropic plastic components with a distinct laminar structure due to resin flow in the mold in combination with rapid cooling. [2][3][4][5][6][7][8][9] Flow pattern, shear, and temperature gradients in an injection molding cavity determine the molecular orientation and crystallinity of the polymer, which in turn determine the properties of the molded parts. Shear stresses and cooling rates of the resin are highest in the vicinity of the mold wall, which results in an oriented layer near the surface of the molding.…”