Liquid-crystalline polymer-thermoplastic composites

Combined liquid crystalline polymers, 49 Combustion testing, 245 Composites, thermoplastic, 32 Compression force deflection (CPD), 244 Compression tests, 242 Condensation... 

Another important application of thermoplastic fibers such as poly ether ether ketone (PEEK), Poly etherimide(PEI), and VectranM andHS (Vectranis the trade mark of Hoechst liquid crystalline polymer) is in making thermoplastic matrix composites. Commingled yams of the reinforcement and matrix such as quartz/PEEK, glass/PEI, Vectran HS/M are used to make the composites wherein the matrix yarn fuses to form the continuous phase of the composite. 

Novel Composites from Blends of Amorphous and Semicrystalline Engineering Thermoplastics with Liquid-Crystalline Polymers... 

S. Saikrasun, S. Bualek-Limcharoen, S. Kohjiya, and K. Urayama. Thermotropic liquid-crystalline copolyester/thermoplastic elastomer in situ composites. I. Rheology, morphology, and mechanical properties of extruded strands. J. Appl. Polym. ScL, 89 2676-2685, 2003. 

S. Saikrasun and T. Amomsakchai. Isothermal decomposition behavior and dynamic mechanical properties of in situ-reinforcing elastomer composites based on thermoplastic elastomers and thermotropic liquid crystalline polymer. / Appl. Polym. ScL, 103 917-927, 2007. 

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. 

The free volume of thermoplastic miscible blends has also been determined as a function of blend composition (Zhou et al. 2003 Campbell et al. 1997 Roland and Ngai 1991). Those studies have shown that the degree of blend miscibility alters the free volume behavior as a function of blend composition. On the other hand, Hsieh et al. (2000) have studied a number of blends containing only thermotropic liquid crystalline polymers TLCP s as the only components. That work showed that regardless of their various miscibilities, TLCP blends tend to display smaller, fewer free volume sites than expected from a weighted average. This observation has been ascribed to the intrinsic affinity of nematic TLCP s. 

IN SITU COMPOSITES FORMED WITH LIQUID CRYSTALLINE POLYMERS AND THERMOPLASTIC MATRICES... 

It has been well recognized that melt blending of a thermotropic liquid crystalline polymer (LCP) and an isotropic polymer produces a composite in which fibrous LCP domains dispersed within the blend act as a reinforcement il ). The so-called insitu composite possesses several advantages in comparison with the inorganic reinforced thermoplastic composites. Firstly, LCP lowers the blend viscosity in the actual fabrication temperature range (3-5), Hence, the enhanced processability endows moldability for fine and complex shaped products. 

Done, D., Sukhadia, A., Datta, A., Baird, D. G., Generation of thermoplastic composites from blends of liquid crystalline polymer with polypropylene, SPE ANTEC 36 %51 (1990). 

The processing of an immiscible or incompatible polymer pair in which the dispersed phase forms in situ reinforcing fibrils can result in an appropriate morphology and improvement in the mechanical properties. This can be achieved by blending thermotropic liquid crystalline polymers (TLCP) with thermoplastics. These blends are often referred to as in situ composites because in the flow fields that occur during polymer processing operations, e.g., in the advancing melt front... 

The liquid crystalline polymers find more applications in smart composite materials. The popularity of LCP is growing very fast because of its ease of processing. It also helps other engineering thermoplastics to process very smoothly even at higher temperature. This happens mainly due to the fibril formations of LCP in presence of other polymer matrix. From the above mentioned areas of LCPs, it is clear that new results arise due to the incorporatiOTi of polymeric LCP in to the other polymer systems. It is very much clear that in future it will create its own vast area in the field of polymer blends and nanocomposites. 

Sukhadia AM, Done D, Baird DG (1990) Characterizatimi and processing of blends of polyethylene terephthalate with several liquid crystalline polymers. Polym Eng Sci 30(9) 519-526 Thranas LD, Roth DD (1990) Films from liquid-oystals. Chemtech 20(9) 546-550 Tjong SC (2003) Stracture, morphology, mechanical and thermal characteristics of the in situ composites based on liquid crystalline polymers and thermoplastics. Mater Sci Eng R Rep 41 (l) l-60... 

Kayaisang S, Amomsakchai T, Saikrasun S (2009) Influence of liquid crystalline polymer and recycled PET as minor blending comprheological behavior, morphology, and thermal properties of thermoplastic blends. Polym Adv Technol 20 1136-1145 Kim GM, Michler GH, Reichert P, Kressler J, Mufliaupt R (1998) Micromechanical deformation processes in PA12-layered silicate nanocomposite. Polym Mater Sci Eng 79 178 Kiss G (1987) In situ composites bloids of isotropic polymers and thermotropic liquid crystalline polymers. J Polym Eng Sci 27 410... 

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