Miscibility studies

At temperatures just below melting, the material will start to flow in a liquid-like manner, causing a dramatic reduction in the moduli. Thus, it is advisable to design experiments in the correct fashion by defining a final temperature that is safe enough to avoid spreading and to prevent the polymer blend from sticking to the probe of the DMTA analyzer. 

The complex modulus components i and E are frequently modeled in the frequency domain by means of the so-called Cole-Cole [43] plot, that is, E =j ), and application of the Havriliak-Negami model [44], provided that there is no overlapping between a and relaxations  

The Kohlausch-Williams-Watts model [45,46] can also be used in the time domain, by means of Eq. (12.12)  

Although the modeling of viscoelastic behavior in the frequency and time domains is very interesting from a scientific point of view, it is beyond the scope of this chapter, which is focused more on the technological applications of DMTA. A summary of the main frequency-domain models is shown in Table 12.1, and further information on this subject is available elsewhere [31]. 

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Kyu, T. and Yang, J. C. 1990. Miscibility studies of perfluorinated Nafion iono-mer and PVDF blends. Macromolecules 23 176-182. 

In the recent miscibility studies with a-methyl styrene/acrylonitrile copolymer and a a-methyl styrene/methyl methacrylate/acrylonitrile terpolymer (8), it was found that almost all miscible second components contain amides, imides, nitriles, or esters, each of which contains lone-pair electrons capable of donor-acceptor complexation—a state which... 

Application of this method for miscibility studies of blends of ethylene-vinyl acetate copolymer (45 wt.- % Ac) with chlorinated polyethylene (52 wt.- % Cl) at a constant frequency of 37 Hz is demonstrated in Fig. 13. The method has shown single T s for the blends studied. The Maxwell-Winger-Sillars conductivity effect which appears after the glass transition temperatures is also shown in this Figure. 

Recently, the miscibility of CO rubber with PMMA over the entire range of concentrations and molecular weights has been confirmed (1 ). There is a broadening of the glass transition which reaches a maximum at about 30% PMMA. However, even at that concentration, the polymers are truly miscible. Studies of compatibility of CO rubber and some copolymers have been reported with other methacrylate polymers and also with acrylate polymers over a wide variety of conditions (Llf 12). Another reason for blending with CO is that CO contains chlorine which tends to enhance x-ray absorption, especially near the absorption edge of 4.4 A. It was hoped that the in-rrease in absorption would produce more secondary... 

Miller, C. A. Fort, Jr. T. "Low Interfacial Tension and Miscibility Studies for Surfactant Tertiary Oil Recovery Processes", Annual Tech. Progress Report to DOE for period Dec. 1978 - Nov. 1979. 

One practical implication of the FH model, which has been used in the industry for miscibility studies (choosing suitable solvents), comes from thermodynamic stability analysis of the model. Applying the stability Equations 16.30 to the FH model, the critical values of the FH interaction parameter and of the concentration are found ... 

A complete characterization of liquid crystalline polymers should include at least two aspects the characterization of the molecular structure and that of the condensed state structure. Since the first characterization is nothing more than what is practiced for non-liquid-crystalline polymers, we will restrict the discussion to only a short introduction of methods mostly used in the characterization of the presence and the main types of polymeric liquid crystal phases. The methods include the mostly used polarizing optical microscopy (POM, Section 4.1), differential scanning calorimetry (DSC, Section 4.2) and X-ray diffraction (Section 4.3). The less frequently used methods such as miscibility studies, infrared spectroscopy and NMR spectroscopy will also be discussed briefly (Section 4.4). 

Optical texture observations and X-ray investigations showed that the polyacrylate 41 PA 3 and the copolymer 45 (x=0.8) form nematic phases. The polymethacrylate 41 PMA 3 and the copoly ether 45 (x=0.55) display no liquid crystallinity at rest, but exhibit a virtual isotropic liquid-nematic transition a few degrees below Tg, as evidenced by miscibility studies. Copolyether 46 does not show any threaded or schlieren texture, which would be characteristic of a nematic. 

A. Z. Aroguz and B. M. Baysal. Miscibility studies on blends of poly(phen-ylene oxide)/brominated polystyrene by viscometry. Eur. Polym. J., 42(2) 311-315, February 2006. 

Basavaraju, K.C. Damappa, T. Rai, S.K. Preparation of chitosan and its miscibility studies with gelatin using viscosity, ultrasonic and refractive index. Carbohydr. Polym. 2006, 66 (3), 357-362. 

Conclusions T-m.d.s.c. has already become an indispensable tool for polymer blends studies. Its main advantage is in resolving phase behavior in those situations where additional exothermic processes are present. However, as far as miscibility studies of polymer blends involving components with comparable glass transition temperatures is concerned, we still have to rely on the enthalpy recovery method, that is, assuming that thermal analysis is the experimental technique selected. 

E. Chen, M.P. Wolcott, Miscibility studies of paraffin/polyethylene blends as form-stable phase change materials. Eur. Polym. J. 52, 44-52 (2014)... 

V.H. Torres, C.J.V. Rodrigues, C.C.A. Ramos, Poly(vinyl alcohol)/poly(acrylic acid) blends miscibility studies by DSC and eharacterization of their thermally induced hydrogels. J. Appl. Polym. Sci. 50, 777-792 (1993)... 

Zhuang, H. R, Pearce, E. M., and Kwei, T. K. 1994. Miscibility studies of poly(styrene-co-4-vinylbenzenephosphonic acid diethyl ester) with poly(p-vinylphenol). Macromolecules 27 6398-6403. 

The effect of the metal ion was investigated, too (Figure 27). Except for the lead complex, all complexes showed an enantiotropic, columnar mesophase characterized as Coh by miscibility studies with the zinc complex. As for the phthalocyanines, the lead ion was located out of the porphyrin plane but here, this distortion and the consequent disturbance of the tt stacking led to total suppression of the mesophase. The transition temperatures were similar for all mesomorphic metal complexes, with a perceptible effect of the metal on the clearing temperatures, which... 

In the meantime, Ohta et studied the complete series of symmetric copper complexes ((53) M = Cu R = R = C H2 +i, = 0 to 14), which confirmed the previous results. The ligand showed a crystal smectic E phase from the octyl derivative onwards as determined by miscibility studies. The first four complexes ((53) M = Cu R = R = C H2 +i, = 0 to 3) were not mesomorphic, then a mono tropic phase was detected for = 4, which became enantiotropic for > 5. Moreover, for n = l and 8, the copper complexes showed an additional mesophase, while the nonyl derivative exhibited two additional mesophases. Crystalline structures of some tetra-alkyl copper, palladium, and nickel complexes of / -diketonates revealed that the flat molecular species were stacked into columns, the planes of the molecules forming a small tilt with respect to the columnar axis-these columns were further organized into layers. Variable-temperature and NMR ... 

Thermoplastic-modified epoxy resins cured with different functionalities amine mixtures. Kinetics and miscibility study. Journal of Thermal Analysis and Calorimetry, Vol.97, No.3, (June 2009), pp. 969-978, ISSN 1388-6150. 

Park Dae Soon, Kim Seong Hun. (2003). Miscibility Study on Blend of Thermotropic Liquid Crystahine Polymers and Polyester. J. Appl. Polym. ScL, 87(11), 1842-1851. 

Wang Y, Gob SH, Chung TS. Miscibility study of torlon(r) polyamide-imide with matrimid(r) 5218 polyimide and polybenzimidazole. Polymer 2007 48(10) 2901-9. 

S. M. Ashraf, S. Ahmad, U. Riaz, M. Alam and H. O. Sharma, Miscibility studies on linseed oil epoxy blend with poly(methacrylic acid) ,/Appl Polym Sci, 2006, 99, 2512-19. 

KAV Kavlak, S., Can, H.K., and Guener, A., Miscibility studies on poly(ethylene glycol)/dextran blends in aqueous solutions by dilute solution viscometry, J. Appl. Polym. Sci., 94, 453, 2004. 

AHM Ahmed, A.A., Jayaraju, J., Sherigaia, B.S., Bhojya, H.S.N., and Keshavayya, J., Miscibility studies of dextran/poly(vinyl pyrrolidone) blend in solution, J. Macromol. Sci. Part A PureAppl. Chem., 45, 1055, 2008. 

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