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Folded chain model of highly drawn polyethylene
Author(s) -
Peterlin A.
Publication year - 1969
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760090305
Subject(s) - amorphous solid , materials science , polyethylene , perpendicular , composite material , crystal (programming language) , molecule , polymer , crystallography , micelle , geometry , chemistry , mathematics , organic chemistry , aqueous solution , computer science , programming language
Neither the fringed‐micelle, fringed‐fibril or extreme folded‐chain models explain the morphological and mechanical properties of highly drawn polyethylene. The modified folded‐chain model, assuming that a substantial fraction (between 5 and 30 percent) of the molecules do not fold back at the crystal surface but go through the “amorphous” surface layer and enter the next crystal, avoids the insufficiencies of the above mentioned models. The elastic modulus and tensile strength of drawn polyethylene, both increasing with draw ratio, are to a large extent the consequence of the molecules bridging the quasi‐amorphous layers and interconnecting the folded‐chain lamellae oriented more‐or‐less perpendicular to the machine direction. The folds create enough space for the accommodation of more‐or‐less extended tie molecules in the quasi‐amorphous layers between the lamellae. Electron microscopy and calorimetry of samples as drawn, annealed and/or etched with fuming nitric acid support the model.