Lozenge, truncated

Fig. 10 Four common types of crystal habit in polyethylene and long alkanes (a) rhombic lozenge bounded by 110 facets (b) lozenge truncated by curved 100 faces (Toda s type B) (c) leaf-shaped crystal bounded solely by curved 100 faces (step propagation rate v equals h = Gno/sin(

Fig. 16 Series of interference contrast optical micrographs of an initially 4.2 wt % solution of n-Ci98H398 in phenyldecane at successive times (indicated) upon reaching Tc = 97.4 °C. The progress of the dilution wave is shown in (b) through (f), triggering the processes of crystallization of needle-like extended-chain crystals and simultaneous dissolution of folded-chain crystals. The needles form along the two 100 faces of the truncated lozenge shaped folded-chain crystals, with a third parallel crystal often appearing in the middle. Bar = 20 pm. (From [44] by permission of American Physical Society)...

Fig. 22 Ratio of growth rates Gioo/Gno vs. crystallization temperature for extended-chain crystals of Ciggfbgg from 2% (w/v) solution in octacosane (diamonds) and for linear polyethylene from 0.05% solutions in hexane (squares). The polyethylene crystal at Tc = 70.0 °C and the C198H398 crystals above Tc = 110 °C are non-truncated lozenges these form for any Guo/ cos( /2) > G100, where cp/2 = tan 1(flo/ o) and ao, b0 are unit cell parameters (cf Fig. 10). Data for PE are from [32] (from [45])...

Fig. 19.6. Natural logarithm of G vs. crystallization temperature (Tc) (.4) and super-cooling (T /TziT) dependence of natural logarithm of G plus the molecular transport term of ziE/RT (Q) for PE [53]. Broken lines indicate morphological transition from truncated lozenge to leticular crystal...

Fig. 1. A truncated lozenge of linear polyethylene, crystallized from 0.01% solution in xylene, with boundaries delineating its six sectors and a step at the outer edge where the crystallization temperature was reduced from 90 to 76 = C. From Ref. 18.

Figure 16.13 Biight-field electton micrograph showing a truncated polyethylene lozenge. The crystal can be seen to be divided into six sectors. From Basseu rr a/. (1959) [1131.

Crystals of 120 x 10 fraction showed morphologically quite different shapes from those of the 14 x 10 and 32 x 10 fractions. The external shape is close to truncated lozenge Bassett et al. [151] have reported similar shapes for a high molecular mass fraction. The growth front of 110 growth sectors is serrated and divided into small growth tips similar to the tips of lenticular crystals. 

Generally in regime I the habit of single crystals is lenticular, whereas the habit of the polycrystallite aggregates is axialitic. In regime II the lamellae have truncated lozenges shape, whereas the superstructure is spherulitic. 

Figure 3.6 Sketch of top views of lozenge-shaped (left, as in Fig. 3.1) and truncated lozenge-shaped (right, as in Fig. 3.16) crystals of polyethylene. The crystallographic a-axis it to the right and 6-axis is vertical up. Adjacent reentry folding is assumed along each growth face. Solid lines represent successive fold planes, while dotted lines indicate sector boundaries that separate distinct fold domains. From Wunderlich [6] with kind permission from the author.

Figure 5.3 Morphologies of polyethylene single crystals (a) lozenge-shaped tent type, (b) truncated-lozenge-shaped tent type, (c) two halves of truncated lozenge-shaped chair type, and (d) truncated lozenge-shaped chair type with spiral terraces from screw dislocations [11].

Figure 7 Polyethylene lamellae crystallized from solution (a) lozenge shaped (b) truncated lozenge shaped...

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