Morphology liquid-crystalline polymers

While no direct evidence of liquid crystallinity in PET-BB copolymers has been reported, the high-BB-content copolymers have been shown to possess morphologies similar to those of liquid crystalline polyesters [40], and show major changes in both melt relaxation times and fiber tensile moduli, suggestive of structural organization in a frustrated liquid crystalline polymer (LCP) (Table 6.3 and Figure 6.4) [41, 42],... 

Morphology evolution in binary mixtures containing liquid-crystalline polymers have been the subject of several studies in recent years [21, 99,100], The... 

In liquid-crystalline polymers, order may include packing of mesogenic, rigid side chains. Correspondingly, terrace-like (layered) morphologies can form in size-domains, which are in the range of typical lamellar dimensions. These can easily be visualized by AFM. 

In contrast to the rod-coil diblock copolymer consisting of perfectly monodisperse rods, the liquid crystalline morphologies of rod-coil diblock copolymer containing polydisperse rods seem to be studied in less detail. In certain cases, the polydisperse nature of the rod-segments could hinder self-assembly into regularly ordered supramolecular structures. However, due to relatively simple synthetic procedures, liquid crystalline polymer can be of benefit for new materials with controlled internal dimensions ranging from the nanometer to macroscopic scale. 

The morphology of the fracture surfaces of both the extruded and injection-molded specimens was studied via scanning electron microscopy (SEM). Although there were many morphologies across the fracture surfaces, highly elongated liquid crystalline polymer domains parallel to the flow direction were observed for both the extruded and molded specimens. 

The majority of polymer blends containing elastomeric, thermoplastic, and/or liquid crystalline polymers are processed by melt extrusion at some point in their history. After melt extrusion with intensive mixing, the morphology of an immiscible polymer blend on a microscopic scale will often consist of a dispersed phase of the more viscous polymer in a continuous matrix of the less viscous polymer (depending upon the relative amounts and viscosities of the two polymers in the blend). A good analogy from every-day experience is a dispersed mixture of viscous oil in an immiscible water matrix. 

This type of approach has been extended to main-chain liquid crystalline polymers 26 with low loadings of ferrocene groups in the side-group structure. In some cases, changes in liquid crystalline morphology from nematic to smectic were observed upon oxidation, as the formation of ionic domains facilitates the generation of layered structures (Figure... 

Crystallization and Morphology of Fibers Prepared from Compatibilized Blends of Polyethylene with a Liquid Crystalline Polymer... 

This review introduces the method of active ester mtheris, and discusses its application to the preparation of a variety erf specialty polymers, including amphiphilic gels, graft copolymers, and side chain reactive and liquid crystalline polymers. The polymerization and copolymerization of activated acrylates by solution and suspension techniques are discussed, and polymer properties such as comonomer distribution, molecular weights, C-NMR spectra and gel morphology are reviewed. Potential applications of these polymers are also highlighted, and the versatility of active ester synthesis as a new dimension of creativity in macromolecular chemistry is emphasized. 

P. Chen, J. Zhang, and J. He. Morphology evolution of a liquid crystalline polymer confined by highly packed glass beads in polycarbonate. Polymer, 46(18) 7652-7657, August 2005. 

S. Saengsuwan, S. Bualek-Limcharoen, G. R. Mitchell, and R. H. Olley. Thermotropic liquid crystalline polymer (Rodrun LC5000)/polypropylene in situ composite films Rheology, morphology, molecular orientation and tensile properties. Polymer, 44 3407-3415, 2003. 

S. Bualek-Limcharoen, 1. Samran, T. Amomsakchai, and W. Meesiri. Effect of compatibUizers on mechanical properties and morphology of in-situ composite film of thermotropic liquid crystalline polymer/polypropylene. Polym. Eng. ScL, 39 312-320, 1999. 

Gopakumar, T. G., Ronrathnam, S., Lele, A., Rajan, C. R., and Fradet, A. 1999. In situ compatibilisation of poly(phenylene sulphide)/wholly aromatic thermotropic liquid crystalline polymer blends by reactive extrusion Morphology, thermal and mechanical properties. Polymer 357-364. 

The unique morphologies of liquid crystalline polymers cause them to undergo numerous thermal transitions which can be observed in a Differential Scanning Calorimeter (DSC) scan. Figure 5 shows a typical scan with descriptions of the transitions and interpretations of the structural arrangements in the several phases. 

Tjong SC. Structure, morphology, mechanical and thermal characteristics of the in situ composites based on liquid crystalline polymers and thermoplastics. Mater Sci Eng R 2003 41(l-2) 1-60. 

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