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Some relationships for the orientational drawing of polymers
Author(s) -
Vlasov S. V.,
Kuleznev V. N.
Publication year - 1995
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.760350209
Subject(s) - materials science , polymer , necking , quantum entanglement , crazing , elasticity (physics) , composite material , ultimate tensile strength , thermodynamics , deformation (meteorology) , physics , quantum , quantum mechanics
The orientational drawing of films from different thermoplastics has been studied. The value of the activation energy of drawing in the regions of forced elasticity (necking), high elasticity, and viscous flow (Δ E 1 , Δ E 2 , Δ E 3 ) has been found to vary directly with the activation energy for viscous flow of the melt (Δ E η ). Here Δ E 1 < Δ E 2 < Δ E 3 = Δ E η . Thus Δ E η characterizes the potential of thermoplastics for orientational drawing under different deformation conditions, since it reflects simultaneously both the intermolecular interaction level and chain flexibility. For maximum chain orientation, the calculated values for the change in the entropy are close to that of the entropy change during crystallization (melting) of the same polymer. The deformation of polymer may be described as a deformation of an entanglement network from the standpoint of classic elasticity theory. Some parameters for an entanglement network were calculated from the results of the drawing experiments. The density of the entanglement network (DEN) depend on the polymer composition: For flexible‐chain polymers the DEN is less, for rigid‐chain polymers (with coiled chains) it is higher. The DEN affects the maximum (prebreak) drawing ratio: The greater the DEN, the smaller the ratio to which a film can be drawn. At high orientation, the tensile strength of different polymer films tend to be similar, if drawing is not accompanied by crazing.