UHMPE-bauxite

The situation changes in the case of solid-phase (semicrystalline) polymer uniaxial drawing. As the experimental estimations shown [5], the Poisson s ratio value for initial pol5aneric materials (componors UHMPE-Al and UHMPE-bauxite) v 0.36 and for these materials extmdates with draw ratio X > 3-v 0.43. From the Eq. (14.3) it follows that A 0.857. This means componors volume obligatory increase, expressed in cracks formation on interfacial boundaries pol5nner matrix-filler [3] ... 

FIGURE 14.1 The dependences of structure fractal dimension on extrusion draw ratio X, calculated according to the Eq. (1.9) (1,2) and the Eq. (1.12) (3) for UHMPE-Al (1, 3) and UHMPE-bauxite (2,3). The shaded region shows the X range, corresponding DS spontaneous change [11]. 

FIGURE 14.5 The comparison of experimental and calculated according to the Eq. (14.15) Oy yield stress values for UHMPE (1), UHMPE-Al (2) and UHMPE-bauxite (3) [31],... 

FIGURE 14.6 The dependences of elasticity modulus E ) and fracture stress (2) on extrusion draw ratio X for componors UHMPE - bauxite [44],... 

The Eqs. (14.21) and (14.22) together with estimated by considered above method parameters A nd allow to calculate the dimensions and [55]. In Fig. 14.11 the dependences of Renyi characteristic dimensions and on extrusion draw ratio for componors UHMPE-Al and UHMPE-bauxite. As one can see, at the definite values X XJ the componors structure transition from multifiractal (canonical spectrum, grows at q increase [59]) to regular fractal D- = occurs and then at X>X - again to multifiractal (pseudospectrum, D decreases at q growth). 

As it follows from the data of Fig. 14.11, the values X for componor UHMPE-bauxite (cp = 0.167) is smaller than corresponding parameter for UHMPE-Al (cpj = 0.260). This assumes X decrease at reduction. As it is known [44], for considered componors extrudates fracture strain e. (or X-p see Fig. 14.8) enhancement at X growth is observed, that is due to interfacial boundaries fracture effect [2]. Therefore, the value 8 is the most sensitive indicator of this structural effect. In Fig. 14.12 the dependences 8j(X) for UHMPE-Al and UHMPE-bauxite are adduced, from which it follows that for the second from indicated componors 8 growth (and, hence, interfacial boundaries fracture [44]) at X increasing begins earlier than for the first (at X > 5 and X > 3, respectively). The cited threshold values X correspond well to the values X 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). 

FIGURE 14.13 The dependences of adaptability resource on voids relative fraction for componors UHMPE - A1 (1) and UHMPE - bauxite (2) [56],... 

Figure 6.33 The dependences of the microhardness on the extra energy localisation regions dimension D for EP-1 (1), EP-3 (2), polyarylate (3), ultra-high molecular polyethylene (UHMPE) (4) and Componor UHMPE-bauxite (5) [87]...

The introduction of bauxite as a filler in ultra-high molecular polyethylene (UHMPE) results in two-fold growth of the extra energy localisation regions dimension from D 4 (UHMPE) to Df 8 (UHMPE-bauxite). In addition the microhardness increases approximately twice (Figure 6.33). 

If the points corresponding to UHMPE and UHMPE-bauxite are disposed on one straight line, then the points for samples of epoxy polymers EP-1 and EP-2 are located on different straight lines (Figure 6.33). With ageing of epoxy polymers (at transition from EP-1 to EP-3) the value of D decreases from D 4.5 to D 3, since the system has a tendency of transition to a more equilibrium state (Figure 6.33). 

As and in the case [45], the studied componors fracture stress <7 depending on X changes extremely and similarly o elasticity modulus E, reaching the greatest values in the region of X. 5 (Fig. 14.6) at bauxite content 40 mas. %. The maximum for componors UHMPE-Al with Al content 70 mas. % is disposed at smaller X values that at the same filler content 54 mas. % [45]. Hence, at filler contents increase strengthening reduction process is displayed earlier (at smaller X). The X increasing induces also extrudates density p monotonous reduction also (Fig. 14.7). 

---