Poly measurements

M Wind, Edit, 1 Handbook of Electronic Measurements , Poly Inst of Brooklyn, Brooklyn,NY. (1956) 22) R. Herzberg,... 

Under viscoelastic measurements poly(cycloalkyl methacrylates) show a loss maximum (designated y), located in the very low temperature range (T <-60 °C), as illustrated in Fig. 6 in the case of poly(cyclohexyl methacrylate). Such a series of polymers has been extensively studied by Heijboer in his Ph.D. thesis [5], by performing viscoelastic studies at 1 Hz (sometimes 180 kHz) as a function of temperature and exploring quite a large number of cycloalkyls, either substituted or not. In cyclopentyl, cyclohexyl, cyclohep-tyl derivatives, the y transition was shown to occur at ca. - 185 °C (180 Hz), - 80 °C (1 Hz), - 180 °C (1 Hz), respectively. The associated activation energies, a> are 13, 47, 26kJmol 1 for the cyclopentyl, cyclohexyl, cycloheptyl derivatives, respectively. 

Conformations of the polymers were studied by CD and optical rotation measurements. Poly-L-lysine is known to exist in disordered, helical and -conformation, depending on the temperature, pH of the system and the solvent used. The side chain of the polymer has a significant effect on the backbone conformation. At neutral pH, poly-L-lysine exists in a random coil structure while at pH above 10, the e-amino group becomes a neutral form and the polymer undergoes transition to a helical structure. In order to elucidate the effect of base substituents on the conformation of poly-L-lysine, CD spectra of the copolymer were measured. 

Free ions, solvent-separated ion pairs, contact ion pairs, and ionic associates can often be experimentally distinguished from each other with the aid of uv, ir, Raman, or nuclear magnetic resonance spectroscopy. According to nmr measurements, poly(styryl anions), I, and poly(dienyl anions), II, are strongly charge delocalized consequently, they exhibit a strong absorption band, sometimes several bands, in the near-ultraviolet region ... 

L. Jiang, Q. J. Xie, L. Yang, X. Y. Yang, S. Z. Yao, Simultaneous EQCM and diffuse reflectance UV-Visible spectroelectrochemical measurements poly(aniline-co-o-anthranilic acid) growth and property characterization, Journal of Colloid and Interface Science 2004, 274,150. 

In a first set of measurements poly(styrene) samples differing in chain length were mixed with their brominated derivatives and the authors determined the maximum tolerable bromine content. A, for a 50/50 (w/w) blend to remain homogeneous, i.e., transparent. A was found to increase with decreasing chain length of the original poly (styrene). A second set concerned 50/50 mixtures of substituted Dolvfstvrenes) of different bromine content. Kambour et al. found that the maximum... 

Ferraris and Itanlon electrochemically polymerized (68) in propylene carbonate using LiC104 as a supporting electrolyte [124], The film grew rapidly but also quickly dissolved off the ITO electrode when the applied potential was removed. It was possible to prepare films of sufficient insolubility for optical measurements. Poly(68) films could be reversibly cycled between 1.8 and 4.1 V versus Li. Electrical conductivity was 280 Scm. These results were compared with those of polymers from 2,5-bis(2-thienyl)-furan, V-methylpyrrole and thiophene. 

Figure 12.24 Using the Surface Forces Apparatus, the repulsive forces between polymer chains on both crossed cylinders, left, and one coated surface and one clean mica sheet, right, can be measured. Poly(ethylene oxide) anchors the nonadsorbing polystyrene chains to the mica, with toluene as the solvent.

Molecular weight of the polymer was determined Gel Permeation Chromatography. A Toso HLC-8020 was emplc ed to measure polys ene-equivalent molecular weight. 

Strauss and Williamst have studied coil dimensions of derivatives of poly(4-vinylpyridine) by light-scattering and viscosity measurements. The derivatives studied were poly(pyridinium) ions quaternized y% with n-dodecyl groups and (1 - y)% with ethyl groups. Experimental coil dimensions extrapolated to 0 conditions and expressed relative to the length of a freely rotating repeat unit are presented here for the molecules in two different environments ... 

Simha equation), where a/b is the length/diameter ratio of these cigarshaped particles. Doty et al.t measure the intrinsic viscosity of poly(7-benzyl glutamate) in a chloroform-formamide solution and obtained (approximately) the following results ... 

Plazek et al.t measured the viscosities of a poly(dimethyl siloxane) sample of = 4.1 X 10 over a range of temperatures using the falling-ball method. Stainless steel (P2 = 7.81 g cm" ) balls of two different diameters,... 

Figure 3.16 Some experimental dynamic components, (a) Storage and loss compliance of crystalline polytetrafluoroethylene measured at different frequencies. [Data from E. R. Fitzgerald, J. Chem. Phys. 27 1 180 (1957).] (b) Storage modulus and loss tangent of poly(methyl acrylate) and poly(methyl methacrylate) measured at different temperatures. (Reprinted with permission from J. Heijboer in D. J. Meier (Ed.), Molecular Basis of Transitions and Relaxations, Gordon and Breach, New York, 1978.)...

The time-temperature superpositioning principle was applied f to the maximum in dielectric loss factors measured on poly(vinyl acetate). Data collected at different temperatures were shifted to match at Tg = 28 C. The shift factors for the frequency (in hertz) at the maximum were found to obey the WLF equation in the following form log co + 6.9 = [ 19.6(T -28)]/[42 (T - 28)]. Estimate the fractional free volume at Tg and a. for the free volume from these data. Recalling from Chap. 3 that the loss factor for the mechanical properties occurs at cor = 1, estimate the relaxation time for poly(vinyl acetate) at 40 and 28.5 C. 

Williams and Ferryf measured the dynamic compliance of poly(methyl acrylate) at a number of temperatures. Curves measured at various temperatures were shifted to construct a master curve at 25°C, and the following shift factors were obtained ... 

The solute molecular weight enters the van t Hoff equation as the factor of proportionality between the number of solute particles that the osmotic pressure counts and the mass of solute which is known from the preparation of the solution. The molecular weight that is obtained from measurements on poly disperse systems is a number average quantity. 

Table 9.3 lists the intrinsic viscosity for a number of poly(caprolactam) samples of different molecular weight. The M values listed are number average figures based on both end group analysis and osmotic pressure experiments. Tlie values of [r ] were measured in w-cresol at 25°C. In the following example we consider the evaluation of the Mark-Houwink coefficients from these data. 

Bhatnagar and Biswast measured the turbidity at 436 nm of 2l single sample of poly(methyl methacrylate) in several solvents, including acetone and methyl ethyl ketone (MEK) ... 

Antimony Oxide. The effect of antimony trioxide on the oxygen index of flexible poly(vinyl chloride) containing from 20 to 50 parts of plasticizer is shown in Figure 2. The flame resistance as measured by the oxygen index increases with the addition of antimony oxide until the oxygen index appears to reach a maximum at about 8 parts of Sb202. Further addition of antimony oxide does not have any increased beneficial effect. 

The limiting oxygen index of Tefzel as measured by the candle test (ASTM D2863) is 30%. Tefzel is rated 94 V-0 by Underwriters Laboratories, Inc., in their burning test classification for polymeric materials. As a fuel, it has a comparatively low rating. Its heat of combustion is 13.7 MJ/kg (32,500 kcal/kg) compared to 14.9 MJ /kg (35,000 kcal/kg) for poly(vinyHdene fluoride) and 46.5 MJ /kg (110,000 kcal/kg) for polyethylene. 

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