Dielectric behavior poly

Keywords Viscoelasticity Glass transition temperature Relaxational processes Dielectric behavior Dynamic mechanical behavior Poly(methacrylate)s Poly (itaconate)s Poly(thiocarbonate)s Spacer groups Side chains Molecular motions... 

Mechanical and dielectric behavior of poly(methacrylate)s with cyclohexyl groups in the side chain have been reported as it was described above and the viscoelastic information obtained from these polymeric systems is very broad and give confidence about the molecular origin of the fast relaxation processes that take... 

Because of the potential interest of these materials, Sanchis and coworkers [64] shows that it is interesting to know the dielectric behavior of two heterocyclic poly(methacrylate)s PTHFM and poly(3-methyl tetrahydrofurfuryl methacrylate) P3MTHFM, (see Scheme 2.9)and the comparison of the relaxation properties of these two polymers. 

Several work are concerned with the synthesis, characterization, dielectric behavior and conformational analysis of dendronized Polymers. Poly(methacrylates) containing phtalimidoalkyl moieties in the side chain have been recently studied i.e. poly(3,5-diphtalimido alkylphenyl methacrylate)s with ethyl (P-EthylGi), propyl (P-PropylGi) and butyl (P-ButylGi) chains as spacer groups. Where Gi indicates first generation [112],... 

Arnold CA, Summers JD, Chen YP, Yoon TY, McGrath BE, Chen D, McGrath JE (1989) Soluble polyimide homopolymers and poly (siloxane imide) segmented copolymers with improved dielectric behavior polyimides In Feger C, Khojasteh MM, McGrath JE (eds) Materials chemistry and characterization. Elsevier, Amsterdam... 

Wesenberg GE, Vaughan WE. Dielectric behavior of poly electrolytes. III. The role of counterion interactions. Biophys Chem 1983 18 381-390. 

Dielectric Behavior The dielectric loss behavior of poly-sulfone samples was measured below 23 C as a function of unasso-... 

Polyethylene samples were also exposed to conditions which created 0.4% clustered water and dielectric data taken at low temperatures on the samples. The same loss maximum noted In polycarbonate and polysulfone near -100 C at 1 kHz was also noted In polyethylene. A special polyethylene sample was molded around a PTFE sheet. The PTFE was removed and replaced with distilled water. This sample was equivalent to a thin water layer between polyethylene sheets. The dielectric behavior of this sample was quantitatively equivalent to that of the polyethylene containing spherical clusters of water if the difference in geometry of the water phase is taken into account. Figure 7 shows the logarithm of the frequency of loss maxima due to water clusters versus reciprocal temperature for polyethylene, polycarbonate, poly(vlnyl acetate and polysulfone. The polysulfone data from Allen are shown for comparison and It Is seen that the data can be Interpreted as a single mechanism with an activation energy of 7 kcal/ mole. 

Watanabe, H., Y. Matsumiya, J. Takada, H. Sasaki, Y. Matsushima, A. Kuriyama, T. Inoue, K. H. Ahn, W. Yu, and R. Krishnamoorti. 2007. Viscoelastic and dielectric behavior of a polyisoprene/poly(4-tert-butyl styrene) miscible blend. Macromolecules 40 5389-5399. 

Poly (ethylene terephthalate) (PET) is one of the most common polymers provided by the polymer industry for fiber and packaging purposes [24]. As far as polymer crystallization is concerned, PET can be considered as a paradigm of a crystallisable polymer due to the fact that PET can be obtained either in the amorphous state or with a controlled amount of ciystalUnity. Therefore, PET has been used to study the influence of crystallinity in a great variety of physical properties including thermal behavior [16,25-29], structure development [30-33] and mechanical and dielectric behavior among others [13,14,34,35]. Figure 21.7 presents the dielectric loss, e", and dielectric constant, e, for amorphous PET at T > 7 as a function of frequency for different temperatures. 

Damaceanu, M.-D. Musteata, V.-E. Cristea, M. Bruma, M., Viscoelastic and Dielectric Behavior of Thin Films Made from SUoxane-Containing Poly(oxadiazole-imide)s. Eur. Polym. J. 2010,46,1049-1062. 

Dielectric behavior of poly(amino acid) solids has also been studied[27-29]. In this chapter we will present... 

This material, commercialized by Du Pont as Kapton M (vi), exhibits excellent thermal stability and good dielectric behavior. The poly(amic acid) solution in N-methyl pyrrolidone is also... 

Deshmukh RR, Malik MK (2008b) Effects of the composition and nematic-isotropic phase transition on the electro-optical responses of unaligned polymer-dispersed liquid crystals. I. Composites of poly(methyl methacrylate) and E8. J Appl Polym Sci 108 3063-3072 Deshmukh RR, Malik MK, Parab SS (2012a) Dichroic dye induced nonlinearity in polymer dispersed liquid crystal materials for display devices. Adv Mater Res 584 79-83 Deshmukh RR, Parab SS, Malik MK (2012b) Effect of host polymer matrices on electro optical and dielectric behavior of polymer dispersed liquid crystal system. Adv Mater Res 584 531-535... 

The dynamic viscoelasticity of particulate gels of silicone gel and lightly doped poly-p-phenylene (PPP) particles has been studied under ac excitation [55]. The influence of the dielectric constant of the PPP particles has been investigated in detail. It is well known that the dielectric constant varies with the frequency of the applied field, the content of doping, or the measured temperature. In Fig. 11 is displayed the relationship between an increase in shear modulus induced by ac excitation of 0.4kV/mm and the dielectric constant of PPP particles, which was varied by changing the frequency of the applied field. AG increases with s2 and then reaches a constant value. Although the composite gel of PPP particles has dc conductivity, the viscoelastic behavior of the gel in an electric field is qualitatively explained by the model in Sect. 4.2.1, in which the effect of dc conductivity is neglected. 

Summary In this chapter, a discussion of the viscoelastic properties of selected polymeric materials is performed. The basic concepts of viscoelasticity, dealing with the fact that polymers above glass-transition temperature exhibit high entropic elasticity, are described at beginner level. The analysis of stress-strain for some polymeric materials is shortly described. Dielectric and dynamic mechanical behavior of aliphatic, cyclic saturated and aromatic substituted poly(methacrylate)s is well explained. An interesting approach of the relaxational processes is presented under the experience of the authors in these polymeric systems. The viscoelastic behavior of poly(itaconate)s with mono- and disubstitutions and the effect of the substituents and the functional groups is extensively discussed. The behavior of viscoelastic behavior of different poly(thiocarbonate)s is also analyzed. 

There are several works dealing with the dielectric and dynamomechanical behavior of poly(methacrylate)s which can be splitted among those containing aliphatic, saturated cyclic rings and aromatic substituents [27-65],... 

In this system the a relaxation can be analyzed by the symmetric equation of Fuoss-Kikwood and a new model which is similar to Havriliak- Negami equation used in the analysis of dielectric spectroscopy. According to the Tg values calculated for these systems, the free volume can be appropriately described by the free volume theory. The analysis of these families of poly(methacrylate)s allow to understand in a good way the effect of the structure and nature of the side chain on the viscoleastic behavior of polymers [33],... 

Poly(cyclobuty methacrylate)s Dielectric relaxational behavior... 

The dielectric and mechanical relaxations on poly(l,3-dioxan-5yl-methacrylate) (PDMA) [104], show that this polymer present a variety of absorptions due to the versatility of its structural moiety [105]. Recently this behavior have been studied by molecular dynamic simulation using different methods and force fields [106-109], These polymers are analyzed from molecular simulation using different ways but... 

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