FRACTAL MECHANICS OF ORIENTED POLYMERS - Fractal Mechanics of Polymers - page 279

The data of Figs. 4.10 and 4.11 comparison shows, that the value l cr , ob-
tained according to the dependences D- 40 ( q ) and D 40 ( q ), corresponds to the
value l, at which fracture stress sf f drop (Fig. 14.10) or interfacial boundaries
polymer-filler fracture begins [2]. Thus, within the frameworks of multifrac-
tal formalism interfacial boundaries fracture of componors in solid-phase
extrusion process is realized by polymer matrix structure regular fractal state
achievement [56].
FIGURE 14.11 The dependences of critical Renyi dimensions D 40 (1, 2) and D- 40 (3, 4) on
extrusion draw ratio l for componors UHMPE-Al (1, 3) and UHMPE-bauxite (2, 4) [56].
As it follows from the data of Fig. 14.11, the values l cr for componor
UHMPE-bauxite (j n = 0.167) is smaller than corresponding parameter for
UHMPE-Al (j n = 0.260). This assumes l cr decrease at j n reduction. As it is
known [44], for considered componors extrudates fracture strain ef f (or lf, f ,
see Fig. 14.8 ) enhancement at l growth is observed, that is due to interfacial
boundaries fracture effect [2]. Therefore, the value ef f is the most sensitive
indicator of this structural effect. In Fig. 14.12 the dependences e f (l) for
UHMPE-Al and UHMPE-bauxite are adduced, from which it follows that
for the second from indicated componors ef f growth (and, hence, interfacial
boundaries fracture [44]) at l increasing begins earlier than for the first (at
l > 5 and l > 3, respectively). The cited threshold values l correspond well
to the values l cr , estimated from the data of Fig. 14.11. Thus, the theoretical
estimations results (the data of Fig. 14.11) correspond well to experiment
(the data of Fig. 14.12).