Poly dielectric studies

Dielectric loss e" of miscible blends of poly(2-chlorostyrene) (P2CS450 Mp2cs = 4.5 x 10 ) and poly (vinyl methyl ether) (PVME96 Mpvme = 9.6 x 10 ) with various P2CS volume fractions ( )p2cs measured at 1 kHz at various temperatures. (Data taken, with permission, from Urakawa, O., Y. Fuse, H. Hori, Q. Tran-Cong, and O. Yano. 2001. A dielectric study on the local dynamics of miscible polymer blends Poly(2-chlorostyrene)/poly(vinyl methyl ether). Polymer 42 765-773.)... 

Test of time-temperature superposability for dielectric loss data of a miscible blend of cis-polyisoprene (PI12 Mp, = 1.2 x 1(H) and poly(vinyl ethylene) (PVE60 Mpyp = 6 x 1(H) with the PI content rup, = 75 wt%. (Data taken, with permission, from Hirose, Y, O. Urakawa, and K. Adachl. 2003. Dielectric study on the heterogeneous dynamics of miscible polyisoprene/ poly(vinyl ethylene) blends Estimation of the relevant length scales for the segmental relaxation dynamics. Macromolecules 36 3699-3708.)... 

Hirose, Y., O. Urakawa, and K. Adachi. 2003. Dielectric study on the heterogeneous dynamics of miscible polyisoprene/poly(vinyl ethylene) blends Estimation of the relevant length scales for the segmental relaxation dynamics. Macromolecules 36 3699-3708. 

Urakawa, O., Y. Fuse, H. Hori, Q. Tran-Cong, and O. Yano. 2001. A dielectric study on the local dynamics of miscible polymer blends Poly(2-chlorostyrene)/ poly(vinyl methyl ether). Polymer 42 765-773. 

A DIELECTRIC STUDY OF THE LOW TEMPERATURE MOLECULAR MOTIONS IN POLYSTYRENE AND THE POLY /0-. M-. OR P-CHLOROSTYRENES/. PH. D. THESIS. 

Ganesh SD, Pai VK, Kariduraganavar MY, Jay anna MB. Fluorinated poly(arylene ether-1,3,4-oxadiazole)s containing a 4-bro-mophenyl pendant group and its phosphonated derivatives synthesis, spectroscopic characterization, thermal and dielectric studies. Polym-Plastics Technol Eng 2013. 

Bohning, M., Goering, H., Fritz, A., Brzezinka, K.-W., Turky, G., Schonhals, A., and Schartel, B. 2005. Dielectric study of molecular mobility in poly(propylene-gn -maleic anhydride)/clay... 

Klonos, P. Panagopoulou, A. Kyritsis, A. Bokobza, L. Pissis, P., Dielectric Studies of Segmental Dynamics in Poly(dimethylsiloxane)/Titania Nanocomposites. J. Non-Cryst. Solids 2011, 357, 610-614. 

Data reported on the low-temperature crystallization (at —90 C) of (PDMS), by. Y-ray and proton n.m.r., show that crystallization is a bulk phenomenon and not surface induced. Dielectric studies on amorphous and crystalline polymers have been reported. Dynamic Kerr-effects and dielectric relaxation studies of a poly(methylphenyl siloxane) have been reported in the region of its relaxation progress, and it is suggested that a substantial contribution to the process is due to motions about the silicon-aromatic ring bond. ... 

J. Ren, O, Urakawa, K, Adachi, Dielectric study on dynamics and conformation of poly(D,L-lactic acid) in dilute and semi-dilute solutions. Polymer 2003, 44, 847-855. 

Dielectric studies of relaxation behaviour of poly(diethylene glycol ter hthalate) and linear aliphatic polyestershave also been reported. 

A dielectric study on the local dynamics of miscible blends poly(2-chlorostyrene)/poly(vinyl methyl ether). Polymer, 42, 765-773. 

One of the most extensively studied pdymers of medium crystallinity is poly-(vinylidene fluoride). The interest in this polymer results from its use as a piezoelectrical and pyro-electrical material (Nakamura and Wada, 1971 Hiqrakawa and Wada, 1973 Murayama, 1975 Murayama and co-workers, 1975 Muiayama and Hashizume, 1976 Mopsik and Broadhurst, 1975). Many dielectric studies have been made and recent work includes that of Koizumi and co-workers (1969), Sasabe and co-workers (1969), Yano (1970), Kakutani (1970), Osaki and cowoikers(1971), Nakagawa and Ishida (1973), Uemura (1974), Osaki and Iriiida (1974), Yano and co-workers (1974) and Brereton and co-workers (1977). It is evid it from these and eadier studies that the dielectric behaviour of this polymer is one of the most complex of the linear polymer systems. Studies have been made of samples of different (i) ciystal forms, (ii) orientations, (iii) crystallinity, (iv) thermal and electrical histories. At least four relaxation regions are observed, being labelled here as a, Oc,... 

Due to its practical importance as a cable material and due to its special position as a model polymer, polyethylene has been the subject of numerous dielectric studies. In coimnon with poly(vinylidene fluoride), polyethylene shows a complicated relaxation behaviour. Since the chain is intrinsically non-dipolar the material is oxidized, dil( inated or is made by copolymerizing carbon monoxide with ethylene, so that d les can be introduced to act as a probe on the motions of the parent material. Extensive accounts of the eady eiqjerimental wodc are available (McCrum et al.,... 

The influence of additives to polymers, particularly plasticizers, naturally reflects their relaxation behaviour. There have been a number of dielectric studies investigating the influence of plasticizers most extensively with poly(vinyl chloride). These have shown not only the changes in the motion of the polymer chain but frequently motions due to the plasticizer molecule, if polar. The techmque is then related to the matrix isolation method in which the pdyma is the bulk phase. 

In recent years the structure and local composition of polymer blends has attracted much attention due to the commercial importance of these materials. The question of compatibility of the components is always paramount and Wetton et showed that dielectric studies provided information which was difficult to obtain by any other method. Random copolymers of styrene and 4-chlorostyrene were blended with poly(2,6-dimethyl-l,4-phenylene oxide) (PPO). It was shown that compatible blends containing 60% (w/w) of copolymer gave an a relaxation which was far broader than those observed for the parent polymer and copolymer, being indicative of microphase separation in the blend where the domains are smaller than the wavelength of light. This loss-peak-broadening is of the kind observed for mixtures of dibutylphthalate and o-terphenyl where microseparation of the components was inferred, and shows that dielectric studies can demonstrate such incompatibility on the microscale in materials which appear to be compatible when judged by optical or DSC measurements. 

Based on these mechanical loss data and the dielectric loss data for poly(propylene oxide), we expected that dynamic dielectric studies of PPO as a function of temperature would reveal two loss... 

Very sparse dielectric studies of polysiloxane scLCPs below the glassy transition show evidence of only one relaxation process, similar to the -process in polyacrylates, with a very broad distribution of relaxation times.The temperature dependence is Arrhenius and the activation energy of 51 kJ mol matches that of the jSi-process in poly acrylates (see above). Measurements performed on the oriented smectic glass show that... 

The equimolar copolymer of ethylene and tetrafluoroethylene is isomeric with poly(vinyhdene fluoride) but has a higher melting point (16,17) and a lower dielectric loss (18,19) (see Fluorine compounds, organic-poly(VINYLIDENE fluoride)). A copolymer with the degree of alternation of about 0.88 was used to study the stmcture (20). Its unit cell was determined by x-ray diffraction. Despite irregularities in the chain stmcture and low crystallinity, a unit cell and stmcture was derived that gave a calculated crystalline density of 1.9 g/cm. The unit cell is befleved to be orthorhombic or monoclinic (a = 0.96 nm, b = 0.925 nm, c = 0.50 nm 7 = 96%. 

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