Rheology Side chain

Optical and electro-optical behavior of side-chain liquid crystalline polymers are described 350-351>. The effect of flexible siloxane spacers on the phase properties and electric field effects were determined. Rheological properties of siloxane containing liquid crystalline side-chain polymers were studied as a function of shear rate and temperature 352). The effect of cooling rate on the alignment of a siloxane based side-chain liquid crystalline copolymer was investigated 353). It was shown that the dielectric relaxation behavior of the polymers varied in a systematic manner with the rate at which the material was cooled from its isotropic phase. 

The stress relaxation properties of SA-modified wood in media of different pH have also been studied (Nakano etal., 1990a,b, 1991 Nakano, 1993a,b). It was found that an increase in pH led to an increase in stress relaxation properties due to side chain ionization, with maximum swelling of the wood occurring between pH 5-8. In addition, cross-linking within the wood was achieved by treatment with bivalent or trivalent metal ions. The rheological properties of maleic acid esterified wood also show that thermoplasticity is imparted to the wood by such modification (Norimoto etal, 1992). 

Lee KM, Han CD. Microphase separation transition and rheology of side-chain liquid-crystalline block copolymers. Macromolecules 2002b 35 3145-3156. 

In addition to their unusual rheological properties, the nematic phases of polymers, like those of simple compounds, can be oriented by the application of magnetic or electrical fields. These properties have been more fully examined for comb-type polymers with mesogenic side-chains than for polymers with the mesogenic groups in the main chain, since in the comb polymers it is possible to influence the side-chain orientation independently of the main-chain orientation. 

James DF and Walters K, "A Critical Appraisal of Available Methods for the Measurement of Extensional Properties of Mobile Systems" in Collyer AA (Ed), "Techniques in Rheological Measurement", Chapman Hall, London, 1993. Jin S, "Synthesis and Characterization of Side-Chain Liquid Crystalline Polyesters and Polyurethanes", PhD Thesis, Delft, 1995. 

Lyotropic SCLCP are far less well studied by rheology than lyotropic MCLCPs. An example is the discotic SCLCP, as mentioned in Chap. 6 (Fig. 6.15), by Franse et al. (2002-2004). Fig. 16.37 gives a schematic representation of side chain discotic polymers (Franse, 2002). In solution the polymers have a tendency to form networks due to interaction between the discotic side chains. From viscoelastic measurements (G and G" as functions of angular frequency) it appeared that the networks formed in a 13% solution in 1,1,2-trichloroethane are very fragile, with a rubber modulus of not more than IN/m2. 

Figure 8-30 Schematic Diagram of Bonds Within and Between Polypeptide Chains in Dough. Solid lines represent covalent bonds, dotted lines other bonds. (1) Intramolecular disulfide bond, (2) free sulfhydryl group, (3) intermolecular disulfide bond, (4) ionic bond, (5) van der Waals bond, (6) interpeptide hydrogen bond, (7) side chain hydrogen bond. Source From A.H. Bloksma, Rheology of Wheat Flour Dough, J. Texture Studies, Vol. 3, pp. 3-17,1972.

Rheological Behavior. Figure 4 shows the room-temperature steady-shear viscosity as a function of shear rate for PDM-PMAS polymers and their precursors. Polymers with Ciq, C12, and C14 side chains exhibit Newtonian behavior over the range of shear rates monitored. 

In this chapter, we discuss the rheological properties of main-chain nematic LCPs. Rheological data for side-chain nematics can be found in Zentel and Wu (1986), Gu et al. (1993), Colby et al. (1993), Kannan et al. (1993, 1994), and Rubin et al. (1995). Other, excellent... 

Some glycoproteins, particularly those with numerous, generally distributed, oligosaccharide side-chains, are able to form dispersions with stringy characteristics, as in nasal mucus or salivary discharges. The rheological implications of interactions between mucus and dmgs have been studied. As yet there is no coherent view as to what the ideal mucolytic... 

This chapter provides an overview of current researches on liquid crystalline polymers (LCPs). Topics include syntheses of main-chain and side-chain LCFs, structured characterization of LCFs and LCP networks and rheology and processing. Applications of LCP/polymer blends as self-reinforced polymers and electro-optical meterials are also discussed. 

As has already been stated, the verified possibility of extending the reduced variables principles to ABS resins makes it possible to treat these typical heterophase systems as blends of amorphous homophase polymers and plasticizers. One possible explanation is that over the experimental y range it is not possible to separate the contributions of the two different phases, and the materials will behave as homophase polymer. In fact, long-time molten polymer rheology experiments measure viscoelastic processes over the entire molecule, and, as a consequence, molecular compatibility is evaluated (13). On the other hand, high frequency and/or low temperature tests involve the main chain as well as the side chains of the polymer system the segmental miscibility of the polymer-polymer system is then evaluated. It is important in experimental measurements of polymer compatibility to evaluate the actual size of the volume subject to the test. 

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