A Deformation Analysis of a Polyethylene Crystal Subjected to End Forces of Stretching and Lattice Expansion
In a recent study by Hoffman1,2 on a theory of flow-induced fibril formation in polymer solutions, it was proposed that each crystallite could be idealized as a rectangular parallelepiped of length ℓ and a square cross-section of side a, and that the four lateral surfaces could each assume the usual lateral surface free-energy density σ (~ 14 ergs/cm2 for polyethylene). The end surface free-energy density σe, however, was assigned a much larger value, because, according to Hoffman1, each end of the crystallite was subjected to two unique types of microstructure-induced forces of unknown magnitudes, namely, a longitudinal stretching due to the handling of the crystallite, and an equally biaxial expansion due to the crowding of the cilia at the crystal ends.
KeywordsElastic Foundation Lateral Load Lattice Expansion Unit Width Deflection Curve
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