Polymer blends crystallization

D. Aciemo and M. R. Nobile, Thermotropic Liquid Crystal Polymer Blends, (F. P. La Mantia, ed.), Technomic Publishing, Lancaster (1993). 

By analogy with small molecule liquid crystals, where the type of liquid crystal formed is used as a test for miscibility, it is expected that all polymer molecules that form the same type of liquid crystalline phase will be miscible (4). This is in contrast to more traditional polymers where miscibility is the exception rather than the rule. The present work will suggest which of these concepts is applicable to liquid crystal polymer blend systems. 

The suggestion that two liquid crystal polymers are incompatible with each other is contrary to ideas which are well established for small molecule liquid crystals (4). In fact, miscibility with other liquid crystals is one of the criteria sometimes used to establish the type of liquid crystal being dealt with. On the other hand, if the rheological criteria established for other polymer blend systems are valid for liquid crystal polymer blend systems as well, the two materials being discussed in the present work must be incompatible. 

P. Magagnini in Thermotropic Liquid Crystal Polymer Blends (Ed. F. P. la Mantia), Technom-ic, Basel 1993, p. 1. 

La Mantia, L. P., ed., "Thermotropic Liquid Crystal Polymer Blends", Technomic, Lancaster, 1993. 

Miller, M. M. Cowie, J. M. G Tail, J. G Brydon, D. L. Mather, R. R. Fibres from polypropylene and liquid-crystal polymer blends using compatibUizing agents. 1. Assesment of functional and nonfunctional polypropylene-acrylic acid compatibihzers. Polymer 1995, 36, 3107-3112. 

Li Youbing, Shi Wen, Li Jingyuan, et al. Structure and properties of glass fiber reinforced polypropylene/liquid crystal polymer blends. J. Macromol. Sci. Part B. 54 no. 9 (2015) 1144-1152. 

Yonezawa Juniki, Martin Stephen M., Macosko Christopher W., et al. Rheology and morphology of smectic liquid crystal/polymer blends. Macromolecules. 37 no. 17 (2004) 6424-6432. 

Relatively speaking the polymer field has not yet reached this stage, to some degree in fibers and films but even here there is much room for improvement. We have many tools to help us produce the optimtim structiire, and optimum properties pressure induced crystallization, shear induced orientation and crystallization, polymer blend composition to control melt rheology as well as the synthesis processes to produce the desired relationship between internal structure and application properties. This is the area of future research that deserves our attention. 

Aciemo D, Nobile MR (1993) Processing and properties of thermotropic liquid crystalline polymers. In Mantia FPL (ed) Thermoplastic liquid crystal polymer blends. Technomic, New York, p 76... 

Li Y, Pan Y, Sun Z, Sheng X, Shi W, li J, Huang H (2013) The rheological behavior of polyamide-66Aiquid crystal polymer blends (conference paper). Adv Mater Res 631-632 100-103 Lin Q, Yee A (1994) Elastic modulus of in-situ composites of a liquid crystalline polymer and polycarbonate. Polym Compos 15 156... 

Qin Y, Brydon DL, Mather RR, Wardman RH (1993) Fibers fi-om polypropylene and liquid crystal polymer blends 2. Effect of extrusion and drawing conditions. Polymer 34 1202 Seo Y, Hwang SS, Hong SM, Park TS, Kim KU (1995) Effect of die geometry on the structural development of a thermotropic liquid crystalline polymer in a thermoplastic elastomer matrix. Polym Eng Sci 35 1621... 

Due to the particular properties shown by liquid crystal polymer blends, they can be considered for several applications. These materials present excellent moldability and dielectric properties, low coefficient of thermal expansion and good thermal stability [89]. In this way, they can be advantageously used in electronic devices. The use of these materials as polymer electrolytes for batteries was also reported [90]. Automotive and commercial aircraft are other areas in which liquid crystal polymer blends may find application due to their excellent processability, high use temperature, good fatigue resistance, and high modulus/strength [91]. 

The increasing interest in liquid crystal polymer blends arises not only from the academic field, but also from industries focusing on innovation. Despite the higher cost of liquid crystal polymers, blending them with traditional thermoplastics results in some very competitive advantages compared to ordinary materials. The unique properties of the liquid crystal polymer blends make them not only remarkable objects for academic investigation, but also extremely versatile soft materials for industry. 

Mehta A, Isayev AI. Rheology, morphology, and mechanical characteristics of poly(ether ether ketone)-liquid crystal polymer blends. Polym Eng Sci 1991 31 971-80. 

Collyer, A.A., The morphology and rheology of Uquid crystal polymer blends Chap 6 Rheology and Processing of Liquid Crystal Polymers (ISBN 9780412596407) D.A. Ademo, A.A. Collyer (eds), pp. 86-134, Books Express, (Saffron Walden, ESS, United Kingdom) (1996). 

DeMeuse, M.T., Jaffe, M., Model system for liquid crystal polymer blends . Mol Crys Liq Crys V157,535-566 (1988). 

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