Rheology of concentrated solutions of poly(γ‐benzyl‐glutamate)

Abstract

Steady shear viscosity, dynamic viscosity, dynamic modulus, and normal force were measured via rotational rheometry for concentrated solutions of racemic mixtures of poly(benzyl‐L‐glutamate) and poly(benzyl‐D‐glutamate) in m‐cresol. A transition from the isotropic state to liquid–crystalline order with increase in concentration was indicated by optical anisotropy and maxima in all four material functions. This occurred at a critical concentration higher than the Flory prediction. Over a well‐defined range of concentrations and shear stresses, some of the liquid–crystalline solutions exhibited negative first normal‐stress differences that were not due to inertial effects.

Anomalous first normal stress difference behavior of polymer nanocomposites and liquid crystalline polymer composites

“…The negative normal stress difference is one of the most important rheological characteristics of LCPs. Kiss and Porter reported the experimental evidence of negative first normal stress difference of lyotropic LCPs for the first time. Subsequent evidence of negative first normal stress difference ( N 1 ) of lyotropic solutions soon followed in other studies .…”

Effect of Magnetic and Mechanical Fields on Phase Liquid Crystalline Transitions in Solutions of Cellulose Derivatives

“…Flory (1956) has suggested the phase diagram for a polymer -solvent system with the liquid crystalline transition. At a later date such diagrams were built for the systems: PBG -DMF (Wee & Miller, 1971), polycarbobenzoxyline -DMF (Miller et al, 1974, poly-pbenzamide -DMA (Papkov et al, 1974), poly-p-benzamide -DMA, LiCl (Iovleva et al, 1976), poly(p-phenyleneterephthalamide) -H 2 SO 4 (Papkov & Kulichikhin, 1977, Andreeva et al, 1981, PBG -ethylene chloride, PBG -benzyl alcohol (Sasaki et al, 1983), poly(pphenyleneterephthalamide) -H 2 SO 4 -water (Nakajima et al, 1978), PBG -m-cresol (Kiss & Porter, 1977), copolymer on the bases of p-phenylenediamine + terephthalic acid and 4,4"-diphenyldicarboxylic acid) -H 2 SO 4 Lukashova et al , 1978), PBG -DMF and PBG -dicloracetic acid (Konevets et al, 1985), poly(p-benzamide) -DMA -LiCl (Salaris et al, 1976), polyhexylisocyanate and poly(50 % butyl + 50 % p-anisole-3-propyl)isocyanat in tetrachlorethane (Aharoni & Walsh, 1979), copolymer on the bases of pphenylenterephyhalaamide + benzimidazole) -H 2 SO 4 (Iovleva & Banduryan, 2010). The influence of a magnetic field on the liquid crystal structure was studied by Meuer (1968), de Gennes (1968.…”

Simulation Study of Thermotropic LCPs and Prediction of Normal Stress Difference at High Shear Rate

“…Kiss and Proter (1978) first showed the experimental evidence of negative first normal stress difference for lyotropic LCPs (Kiss and Porter, 1978). After that, other researchers also found the evidence of negative first normal stress difference (N 1 )f or lyotropic solution (Baek et al, 1993;Beak and Magda, 1993;Huang et al, 1999).…”