Blends of liquid-crystalline polymers

Toy et al. [1994] investigated the effect of irradiation on blends of liquid crystalline polymers (LCP) with either polyvinylidene fluoride (PVDF) or HDPE (Table 11.9) such blends are useful for making dimensionally recoverable articles. This patent contains many claims but few results. 

P. C. Yung and H. C. Linstid, 111. Blends of liquid crystalline polymers and poly(arylene sulfide)s having reduced viscosities. US Patent 5418 281, assigned to Hoechst Celanese Corporation (Somerville, NJ), May 23, 1995. 

D. G. Baird, R. Mehta, Processing Behavior of Blends of Liquid Crystalline Polymers (PPS... 

Heino, M. and Vainio, T. (1996) Effect of viscosity ratio and processing conditions on the morphology of blends of liquid crystalline polymer and polypropylene, in Handbook of Applied Polymer Processing Technology, (eds N.P. Cheremisinoff and P.N. Cheremisinoff), Marcel Dekker, New York, pp. 233-263. 

Effect of Viscosity Ratio and Processing Conditions on the Morphology of Blends of Liquid Crystalline Polymer and Polypropylene... 

Ramanathan, R., Blizard, K., and Baird, D., Characterization of blends of liquid crystalline polymers with engineering thermoplastics, SPE ANTEC 34 23... 

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). 

Carfagna, C., Amendola, E., and Nicolais, L., Incompatible blends of liquid crystalline polymers and engineering thermoplastics, Int. J. Mat. Prod. Technol. 7 205 (1992). 

Conflicting results have been found for the explicit time evolution of the correlation length during isothermal phase separation. A 1/3-power law in the growth of patterns, which is characteristic for the hydrodynamically controlled Lifshitz Slyozov process, was confirmed in Ref. [99] while an exponential increase over a certain period of time was established in Ref. [21]. Nevertheless, it is evidenced that in blends comprising liquid-crystalline polymers spinodal decomposition and subsequent coarsening processes take a course similarly to isotropic liquid mixtures. 

Very little work has appeared in the literature which deals with blends in which the component materials can cocrystallize. It is generally believed (16.17) that a requirement for cocrystallization is that there must be a close matching of the polymer chain conformations and of crystalline dimensions. Also, some level of miscibility should exist between the two polymers and the crstallization kinetics cannot be very different. Certainly, in the case of liquid crystalline polymers, in general, these requirements would be expected to be met. Some of our recent work (8) has suggested, however, that not all liquid crystal polymers do cocrystallize. The present work suggests that in certain cases it may be possible to achieve this effect. 

Garbarczyk, J., Kamyszek, G. (2000). Influence of Magnetic and Electric Field on the Structure of IPP in Blends with Liquid Crystalline Polymers. In Abstracts of the 38-th Macromolecular lUPAK Symposium. Warsaw, 3, 1195. 

D. M. Malik et al.. Characteristics of liquid crystalline polymer polyester polycarbonate blends, Polym. Engr. Set, 29 (4) 600 (1989). 

Several apects of the blend behaviour has to be considered in order to fully appreciate the effect of liquid crystalline polymers added to thermoplastic matrices. 

Nobile, M.R., L. Incamato, G. Marino, D. Aciemo, in Processing and Properties of Liquid Crystalline Polymers andLCP Based Blends, D. Aciemo, F.P. La Mantia, Eds. Chem-Tec Publishing. Toronto, ON, 1993 p.l95... 

AFM is used at the nanoscale to analyze structure of polymers. It has been used to determine spatial distribution of impact modifier in high impact polypropylene (95), follow pit growth in a film of a blend as a function of exposure time during degradation studies of coatings on metal (96), determine surface topography and molecular organization of liquid crystalline polymers (97), and observe... 

Table4.8 Additional Examples of Liquid Crystalline Polymer Blends with Non-LCP Polymers ...

One of the major applications of LCPs in the mid 1980s involved cookware with 50 wt% filler addition for dual microwave and conventional oven applications. The LCP allowed high temperature utility and the ability to incorporate high filler loadings, which allowed better dimensional stability and lower cost. It would appear that the addition of LCPs to conventional thermoplastics to allow increased filler loadings would be of potential utihty however, this does not appear to be noted in the literature. The ability to accept high filler loadings in thermoplastics by LCP addition to lower viscosity could also yield novel electrically and thermally conductive blends. Additional liquid crystalline polymer blends examples are listed in Table 4.8. 

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