Mechanical Relaxations in Single Crystals of Polyethylene

Abstract

Grace and Company, Cladcsdle, M a r~l a n~ 21029 * This paper was originally published in J. A p p l . Phys., 37, 3385 (1966) and is reproduced here by kind permission of the American Institute of Physics. 14rl EXPERIMENTAL Preparation of Single CrystalsGrex 60-002E (W. R. Grace), a high density polyethylene having 1.4 methyl groups per 1000 carbon atoms, a number-average molecular weight * The accepted terminology of designating the relaxations with Greek letters in order of decreasing temperature is used. Another relaxation, the p relaxation, occurs in branched polyethylene, but this was not observed in the linear polyethylene used in the present work. A general discussion of relaxations in melt-crystallized polyethylene has been given by Boyer.6

Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes

“…Gel ( (Hoffman et al, 1966;Sinnott, 1966) or/and motion of disordered chain segments at the surfaces of polymer crystals (Fischer and Peterlin, 1964). The discussion is widened because of the possible presence of many processes in this relaxation and because of their localization.…”

Mechanical relaxations in polyethylene

“…Sinnott [17] and by Takayanagi and Matsuo [18]. Sinnott measured the dynamic rigidity modulus (for s h e a r in an "average" a-b direction on a-b planes o r in the c direction on "average" a-c, b-c planes) and the corresponding logarithmic decrement.…”

Dynamic mechanical properties and morphology of polyethylene/ethylene vinyl acetate copolymer blends

“…3 Sinnott proposed the ␥ relaxation in both bulk and single-crystal specimens of linear PE can be explained in both bulk and stress-induced reorientation of defects within the PE crystal. 4 Hoffman et al proposed a theory in which the ␥ mechanism is attributed to the reorientation of chains in a loose chain-end induced defect (a vacancy row) within the crystal. 5 The original suggestion related to the dynamic mechanical properties of PE was that the ␥ relaxation is due to motion of the polymer chains in the amorphous regions.…”