Isotactic polypropylene (iPP) exhibits an interesting polymorphic behavior [1-5], sharing four crystalline structures: monoclinic [alpha]-form [6, 7], trigonal [beta]-form [1, 8-12], triclinic [gamma]-form [13, 14] and smectic phase
[15, 16], Among these crystalline forms, [beta]-form is a metastable phase and can only be obtained under the following processing conditions: melt crystallization in the presence of specific heterogeneous nucleating agent (NA) [17, 18], by directional crystallization in certain temperature , or from melts subjected to shear [20, 21].
In Smectic phase
, the molecules possess directional as well as position order; Smectic A phase, for example, exhibits layered structures.
The values of activation energy in smectic phase
at a particular frequency region are more than 250 (KJ/mol), which is similar to the relative conductivity ([sigma]) that showed steep slope in nematic as in smectic phase
During the heating course, the first endothermic peak at 111[degrees]C was associated with the transition from crystallization to the liquid crystalline phase, which revealed the schlieren texture of the smectic phase
. When the temperature was increased to above I21[degrees]C, there was an isotropic transition for the LCER from the liquid crystalline phase.
At high temperature (218[degrees]C), this terphenyl displayed a broad peak (centered around 2[theta] = 20[degrees]), suggesting the presence of a low-ordered smectic phase
(SmA or SmC).
Ferroelectric liquid crystals (FLCs) have salient features over the trivial liquid crystals (LCs) because of their tilted smectic phase
and the chirality of the molecules .
7d and e), or after annealing they exhibited more ordered textures, which could be suggestive of a smectic phase
When the layer spacing is between one and two molecular lengths, the smectic phase
is designated [A.sub.d], where d here stands for dimer.
The monomers favored an intercalated arrangement to form smectic phase
(Scheme 2) (19).
Sample Time (h) [AIBN1 mol [L.sup.-1] [10.sup.-3] p 48 2 (DMAEM[A.sub.79) P 24 1 (DMAEM[A.sub.79]-b-AZO[M.sub.7]) p 24 1 (DMAE[M..sup.79]-b-AZO[M.sub.5]) p 24 1 (DMAEM[A.sub.79]-b-AZO[M.sub.2]) Sample [Monomer] [M.sub.n] PDI mol [L.sup.-1] (GPC) p 12,635 1.09 (DMAEM[A.sub.79) P 0.524 15,228 1.25 (DMAEM[A.sub.79]-b-AZO[M.sub.7]) p 0.282 14,742 1.20 (DMAE[M..sup.79]-b-AZO[M.sub.5]) p 0.134 13,412 1.16 (DMAEM[A.sub.79]-b-AZO[M.sub.2]) Sample Phase transition temperature ([degrees]C) p (DMAEM[A.sub.79) P g51 S88 (DMAEM[A.sub.79]-b-AZO[M.sub.7]) Nl 15 p g48 S79 (DMAE[M..sup.79]-b-AZO[M.sub.5]) Nlll p g41 S78 (DMAEM[A.sub.79]-b-AZO[M.sub.2]) N102 g, glassy phase, S, smectic phase
, N, nematic phase.
The structures of mesomorphic phase (the smectic phase
, , paracrystalline [24-26], conformational disorder crystal , , and microcrystal or nano-crystal [29-31]) rather than the growth of spherulites are formed.
polypropylene is a morphology between amorphous and crystalline phases, and is formed when quenched at a relatively high cooling rate  according to the X-ray observations of smectic phase
by Ferrer-Balas et al.