Dielectric relaxation and molecular motion in poly(vinylidene fluoride)

The dielectric properties of poly(vinylidene fluoride) have been studied in the frequency range 10 Hz to 100 kHz at temperatures between ?196 and 150°C. Three dielectric relaxations were observed: the α relaxation occurred near 130°C, the β near 0°C, and the γ near ?30°C at 100 kHz. In the α relaxation the magnitude of loss peak and the relaxation times increased not only with increasing lamellar thickness, but also with decrease of crystal defects in the crystalline regions. In the light of the above results, the α relaxation was attributed to the molecular motion in the crystalline regions which was related to the lamellar thickness and crystal defects in the crystalline phase. In the β relaxation, the magnitude of the loss peak increased with the amount of amorphous material. The relaxation times were independent of the crystal structure and the degree of crystallinity, but increased slightly with orientation of the molecular chains by drawing. The β relaxation was ascribed to the micro-Brownian motions of main chains in the amorphous regions. The Arrhenius plots were of the so-called WLF type, and the “freezing point” of the molecular motion was about ?80°C. The Cole-Cole distribution parameter of the relaxation time α increased almost linearly with decreasing temperature in the temperature range of the experiment. The γ relaxation was attributed to local molecular motions in the amorphous regions.     

Relaxations of selenium in crystalline and amorphous states

Complex shear modulus at 33 kc./sec. is measured at temperatures of ?150–150°C. for amorphous selenium and crystalline selenium with different crystallinities. The dielectric relaxation at 10 kc./sec. to 3 kc./sec. to 3 Mc./sec. is observed at temperatures of ?32–25°C. for iodine-doped crystalline selenium. It is concluded from the results of this study and of others' that selenium exhibits four relaxations, α, β γ, and δ, in order of descending temperature. The β relaxation is observed only in the amorphous sample above the glass temperature and is assigned to the primary relaxation. The α, γ, and δ relaxations are found in the crystalline selenium. The α relaxation, which is prominent in a highly crystalline sample, is assigned to the crystalline relaxation. The γ and δ relaxations increase in peak height with decreasing crystallinity and are attributed to the disordered region in the crystalline selenium. The dispersion map (logarithm of frequency versus reciprocal absolute temperature of loss maximum) of selenium is presented.     

Internal motions in an alternating copolymer of ethylene and tetrafluoroethylene

Internal motions in an alternating copolymer of ethylene and tetrafluoroethylene were investigated by dynamic mechanical and dielectric measurements and by nuclear magnetic resonance. At 1 Hz the α, β, and γ relaxations were observed at 110, ?25, and ?120°C in a quenched sample. The activation energy was 76 kcal/mole for the α relaxation and 10.6 kcal/mole for the γ relaxation. These relaxations are attributed to the motion of long and short segments in the amorphous regions, respectively. The β relaxation, which was observed only in the dynamic mechanical experiments, appears to occur in the crystalline regions. The copolymer is isomeric with poly(vinylidene fluoride), but it has a higher melting point and a much lower dielectric loss.     

Origin of the γ relaxations in polyethylene and polytetrafluoroethylene

Mechanical relaxation has been studied at 0.67 cps in linear polyethylene (LPE) and polytetrafluoroethylene (PTFE) between ?190 and ?20°C. Specimens were prepared by use of various thermal treatments to produce in LPE a range of crystalline fractions from 0.690 to 0.825 and in PTFE from 0.615 to 0.870. An empirical theory is proposed relating the modulus of the crystalline–amorphous composite solid to the moduli and the volume fractions of the two phases. The empirical theory is shown to be in accord with the bounds of Hill and of Hashin and Shtrikman. The theory is used to determine the magnitudes of the crystalline and amorphous components of the low temperature relaxations in LPE and PTFE from measurements of logarithmic decrement and shear modulus. In PTFE the γ relaxation occurs in the amorphous fraction alone. In LPE the γ relaxation is a composite one, formed from the superposition of a small crystal relaxation and a large amorphous relaxation. For the crystal relaxation in LPE the ratio of relaxed to unrelaxed modulus equals 0.78; for the amorphous relaxation, the ratio equals 0.23. In a specimen of LPE with crystal fraction 0.69 the crystal contribution to the relaxation is 25% of the total. The magnitude of the unrelaxed modulus of the crystal fraction of LPE (modulus of polycrystalline LPE at ?190°C) is in reasonable agreement with theoretical calculations of Odajima and Maeda.     

Piezoelectric properties and molecular motion of poly(β-hydroxybutyrate) films

Piezoelectric, elastic, and dielectric properties of films of poly(β-hydroxybutyrate) (PHB), an optically active natural polymer, were measured as functions of frequency and temperature. In mechanical properties, three relaxation processes were observed at 10 Hz: the α dispersion at 130°C, the β dispersion at room temperature, and the γ dispersion at ?120°C. It was concluded from x-ray diffraction and the thermal expansion coefficient that the α dispersion can be ascribed to thermal molecular motions in the crystalline phase, that the β dispersion is the primary dispersion due to the glass transition, and that the γ dispersion is related to local molecular motion of the main chains in the amorphous phase. Piezoelectric relaxations were also observed in these relaxation regions. It is proposed that the high-temperature process is due to ionic dc conduction. The piezoelectric relaxation at room temperature is ascribed to the increase of piezoelectric activity in the oriented noncrystalline phase, in which the sign of the piezoelectric modulus is opposite to that in the oriented crystalline phase.     

Solid-state relaxations in linear low-density (1-octene comonomer), low-density,and high-density polyethylene blends

Extensive thermal and relaxational behavior in the blends of linear low-density polyethylene (LLDPE) (1-octene comonomer) with low-density polyethylene (LDPE) and high-density polyethylene (HDPE) have been investigated to elucidate miscibility and molecular relaxations in the crystalline and amorphous phases by using a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). In the LLDPE/LDPE blends, two distinct endotherms during melting and crystallization by DSC were observed supporting the belief that LLDPE and LDPE exclude one another during crystallization. However, the dynamic mechanical β and γ relaxations of the blends indicate that the two constituents are miscible in the amorphous phase, while LLDPE dominates α relaxation. In the LLDPE/HDPE system, there was a single composition-dependent peak during melting and crystallization, and the heat of fusion varied linearly with composition supporting the incorporation of HDPE into the LLDPE crystals. The dynamic mechanical α, β, and γ relaxations of the blends display an intermediate behavior that indicates miscibility in both the crystalline and amorphous phases. In the LDPE/HDPE blend, the melting or crystallization peaks of LDPE were strongly influenced by HDPE. The behavior of the α relaxation was dominated by HDPE, while those of β and γ relaxations were intermediate of the constituents, which were similar to those of the LLDPE/HDPE blends. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1633–1642, 1997     

Mechanical relaxations in some ionene polymers. I. Effect of Ion concentration

Dynamic mechanical properties of m,n-ionenes, the structure of which are shown in Figure 1, were examined by torsional braid analysis. Three relaxations designated as α,β and γ were found. The α relaxation, ascribed to the primary relaxation due to an amorphous phase, was observed at 70–130°C, the temperature increasing with an increase of the ion concentration along the polymer chains. The β relaxation at around 0°C was related to the ionic portions of the polymers. The γ relaxation at around–120°C was a so-called local mode relaxation. The γ relaxation peak was split into two peaks in the very slowly cooled 12,10-ionene sample and the formation of an inhomogeneous structure in the amorphous phase is proposed.     

Dynamic mechanical relaxations of polyterephthalates based on trimethylene glycols

The dynamic mechanical relaxations of poly(trimethylene glycol terephthalate) (PTMT), poly(ditrimethylene glycol terephthalate) (PDTMT) and two copolymers obtained from them have been studied between ? 150 and 200°C with a dynamic viscoelastometer. The four polymers show three relaxations that are designated α, β, and γ in order of decreasing temperature. The α relaxation is considered to be the glass transition of the polymers. The β relaxation is wider and weaker than the α, as normally occurs in the polyester series. The γ relaxation takes place at temperatures below ? 100°C and is usually overlapped by the β relaxation. The influence of thermal and mechanical histories on the nature, location, and intensity of the three relaxations is studied and discussed.     

A dielectric study of molecular relaxation in oxidized and chlorinated polyethylenes

A study was made of the dielectric relaxation in polyethylenes rendered dielectrically active through oxidation (0.5–1.7 carbonyls/1000 CH₂) and chlorination (14–22 Cl/1000 CH₂). Both linear and branched polymers were studied. All of the relaxations between the melt and ?196° were studied in the frequency range 10 Hz to 10kHz (100 kHz in the chlorinated samples). In the linear samples a wide range of crystallinities was studied (55% in quenched specimens to 95% in extended-chain specimens obtained by crystallization at 5 kbar). As is consistent with its being a crystalline process, the α peak was found to discontinously disappear on melting of the samples and reappear on recrystallizing on cooling. The disappearance of the smaller crystals before the larger ones appeared to be evident in the isothermal loss versus frequency curves. The relaxation strength of the α process increases with crystallinity. The measured relaxation strength is less than that expected on the basis of direct proportionality to the crystalline fraction with full contribution of all dipoles in the crystalline material. However, the intensity is not sufficiently low for the process to be interpreted in terms of reorientation of localized conformational defects in the crystal. The variation of intensity with crystallinity is best interpreted in terms of full participation of crystalline dipoles but with selective partitioning of both carbonyls and chlorines favoring the amorphous domains. A strong correlation of the α loss peak location (T_max at constant frequency or log f_max at constant T) with crystallinity for both carbonyl and chlorine containing polymers was found. This variation is interpreted in terms of chain rotations in the crystal where the activation free energy depends on crystal thickness. The dependence of log f_max and T_max on lamellar thickness as well as a comparison with the loss peaks of ketones dissolved in parafins indicates that the chain rotation is not rigid and is accompanied by twisting as the rotation propagates through the crystal. In agreement with previous studies the β process is found to be strong only in the branched polymers but can be detected in the chlorinated linear polymer. The β process was resolved from the α in the branched samples by curve fitting and its activation parameters determined. The γ relaxation peak in oxidized polymers including its high asymmetry (low-temperature tail) and increasing ε_max with increasing frequency and temperature when plotted isochronally can be interpreted in terms of a simple nearly symmetrical relaxation time spectrum that narrows with increasing temperature. No increase in relaxation strength with temperature was found. The chlorinated polymers behave similarly but appear to have some Boltzmann enhancement (450–750 cal/mole) of relaxation strength with temperature. The dependence of relaxation strength on crystallinity indicates that the process is an amorphous one. Further, no evidence of relaxation peak shape changes with crystallinity that could be interpreted in terms of a crystalline component in addition to the amorphous one was found. The comparison of the γ relaxation strength with that expected on the basis of full participation of amorphous dipoles indicates that only a small fraction (～10% in oxidized linear polymers) of them are involved in the relaxation. Thus it would seem that a glass–rubber transition interpretation is not indicated but rather a localized chain motion. It is suggested that the γ process, including its intensity, width, and activation parameters, can be interpreted in terms of an (unspecified) localized conformational (bond rotation) motion that is perturbed by differing local packing environments. The thermal expansion lessens the effects of variations in packing and leads to narrowing with increasing temperature. The conformational motion itself leads to increase in thermal expansion and hence a transition in the latter property. Some previously proposed localized amorphous phase conformational motions appear to be suitable candidates for the bond rotation motion. A weak relaxation peak found at temperatures below the γ and at 10 kHz may possibly be the dielectric analog of the δ cryogenic peak found previously mechanically at lower frequencies.     

Mechanical relaxations in some ionene polymers. II. Influence of counterions and absorbed water

Six 6,10-ionenes with different counterions were prepared by ion exchange reactions in aqueous solutions. The counterions were Br, I, CIO₄, BF₄, SCN, and B(C₆H₅)₄. The dynamic mechanical properties of these polymers were investigated by use of a torsional braid analyser. Three relaxations α (25–140°C), β (?30–0°C), and γ (?140–120°C) were observed at the frequencies of 0.3–0.8 Hz. The temperature of the α and β relaxations were largely dependent on the size of counterions, but those of the γ relaxations had little variation. The effects of electrostatic forces in the polymers on each relaxation was discussed. The influence of absorbed water on the α, β, and γ relaxations was examined. The absorbed water in the polymers greatly depressed the temperature of the α relaxations and this phenomenon was interpreted to be the result of the specific hydration on ionic portions.     

Effects of swelling and annealing on the viscoelastic behavior of the melt-crystallized and solution-crystallized polypropylene

The effects of swelling and annealing treatments on viscoelastic behavior were studied in melt-crystallized and solution-crystallized samples of isotactic polypropylene (iso-PP) over the temperature range ?150 to 150°C. The log E″ versus T curves exhibited α, β, and γ peaks in order of decreasing temperature. The β peak of the melt-crystallized sample shifted to higher temperatures after annealing, but was not affected by swelling. The α peak of melt-crystallized polymer was affected by swelling treatments. It increased in height and shifted to lower temperatures almost linearly with the volume fraction of absorbed solvent. The magnitude of the shift was independent of the solvent species—toluene, p-xylene, tetralin, carbon tetrachloride—however, it depended significantly on the temperature at which the sample had been heat treated. For solution-crystallized polymer, no peaks in log E″ were observed in the temperature range of the β peak of melt-crystallized material, but the α peak appeared larger and broader, and at higher temperature than the corresponding peak in the melt-crystallized polymer. After swelling or annealing, the low-temperature component of the α peak of the solution-crystallized sample decreased in height and at the same time a new loss peak appeared at ?55 and 0°C, respectively, is swollen and annealed samples. In particular, in the case of annealing treatments, the high-temperature component of the α peak shifted to still higher temperatures. From these results on the solution-crystallized sample it can be deduced that the segmental motions in the amorphous phase are very strongly constrained by surrounding crystalline phases as compared with those in the amorphous phase of the melt-crystallized sample, and the constraints imposed on the segmental motions are released to a great extent by both treatments. Finally, swelling effects on the γ peak were examined. The γ peak of the melt-crystallized sample decreased in height after swelling. On the other hand, the γ peak of the solution-crystallized sample separated into two peaks, which might be attributed to the mechanical relaxations in the crystalline and amorphous phases.     

Effect of orientation,anisotropy, and water on the relaxation behavior of nylon 6 from 4.2 to 300°K

The relaxation behavior of nylon 6 from 4.2 to 300°K was investigated as a function of orientation, anisotropy and moisture content by using an inverted free-oscillating torsion pendulum. Three new relaxations, δ at 53°K, ? below 4.2°K, and ζ at 20°K, were discovered. The characteristics of these new relaxations strongly depend on the orientation anisotropy, and concentration of adsorbed water in the specimens. The results suggest that the mechanism of the γ process is associated with the motions of both the polar and methylene units. The mechanism of the β relaxation is postulated to originate with motions of both non-hydrogen-bonded polar groups and polymer—water complex units. The behavior of the α peak is consistent with the hypothesis that it originates with the rupture of interchain hydrogen bonding due to the motions of long-chain segments in the amorphous regions. Finally, the data strongly support the proposition that two types of water, tightly bound and loosely bound, exist in nylon 6.     

Effects of melting on dielectric relaxation in poly(hexamethylene sebacamide) (nylon 610)

In order to investigate the role of solid morphology on molecular relaxation in crystaline polymers, the effect of melting on the α relaxation in poly(hexamethylene sebacamide) (nylon 610) was measured dielectrically. It was found that the α loss peak was continuous into the melt with respect to location in the frequency-temperature domain and with respect to the shape of the peak. However, the strength of the process, as measured by the difference in the relaxed and unrelaxed dielectric constants, was discontinuous on melting, the process being much stronger in the melt. These observations are consistent with a two-phase model of discrete crystalline and amorphous regions. The relaxation takes place in the amorphous regions, and melting creates more of this material but does not greatly after its nature. The correlation of the amount of amorphous material as measured by dielectric relaxation with that infrared from density measurements is discussed for nylon610, polyoxymethylene, and poly(ethylene oxide).     

Molecular transitions in an alternating copolymer of ethylene and chlorotrifluoroethylene

Three transitions have been found with peaks at 130°C (α), 88°C (β), and ?65°C (γ), by mechanical relaxation techniques for a quick-quenched sample of an alternating copolymer of ethylene and chlorotrifluoroethylene. The intensity of the α transition was found to increase with an increase in crystalline content. It was observed at 150°C by infrared and x-ray diffraction techniques and by mechanical relaxation spectra on an annealed sample. X-ray diffraction and dichroic infrared measurements were conducted on oriented specimens as a function of temperature. These data showed that the β transition was accompanied by a change in lateral bonding distances in the crystalline phase and a conformational change attributed to an “unkinking” of the molecular chain. The β transition was found to be related to the amorphous phase and the onset of the β peak corresponded to the transition at 35°C found by infrared techniques and previously by a torsional modulus method. It was tentatively assigned to the glass transition. A more definitive assignment of the β transition would depend on a detailed structural analysis of the γ transition. The γ peak was not studied in detail in the present work.     

Structural origin of the cryogenic relaxations in poly(ethylene terephthalate)

The effect of molecular organization (crystallinity, orientation) on the internal friction of poly(ethylene terephthalate) was studied by means of dynamic mechanical measurements at temperatures from 300 to 4.2°K, with a free-oscillating torsion pendulum at 1 Hz. It was found that crystallinity decreases the intensity of the composite γ relaxation at 210°K and gives rise to an additional loss maximum ε at 26°K. Uniaxial orientation broadens the γ relaxation and gives rise to an additional loss peak δ, at 46°K. The δ and ε losses are dependent on molecular organization, occurring only in samples containing aligned, taut chain segments and crystalline structures, respectively. They have a common activation energy of 4 kcal/mole. All three low-temperature relaxations in oriented specimens show pronounced directional anisotropy, which, in the γ loss, may be due to the preferred orientation of noncrystalline chain segments, while in the δ and ε losses, may be associated with the direction of defect structures. On the basis of the observed behavior of the δ and ε relaxations it is suggested that they may involve motions of defect structures and may thus participate in stress-transfer mechanisms at large deformations.     

Cooperative relaxations in semicrystalline fluoropolymers studied by thermally stimulated currents and ac dielectric

Semicrystalline fluoropolymers including poly(tetrafluoroethylene) (PTFE), a 8 mol % hexafluoropropylene (HFP)/92% TFE random copolymer (FEP), and poly(vinyl fluoride) (PVF) were studied using thermally stimulated current depolarization (TSC), ac dielectric, and other thermal analysis techniques. The TSC thermal sampling (TS) technique is emphasized here for the detection of broad and weak “cooperative” relaxations with all three of the polymers studied exhibiting two cooperative (i.e., relatively high apparent activation energy) transitions. The well-studied low-temperature γ relaxation in PTFE at ca. −100°C is characterized by this method as well as the γ relaxation in the less crystalline FEP sample. Higher temperature cooperative glass transitions, associated with constrained noncrystalline regions, are found at ca. 100°C in PTFE and ca. 80°C in FEP at TSC frequencies. Comparisons with relaxation studies of linear polyethylene are made, and the effects of crystallinity on the various transitions are discussed. The unique characterization by the TSC-TS technique in the detection of multiple “cooperative” relaxations, even in the case of overlapping transitions, is emphasized here. An example is the low-temperature relaxation in FEP. Two cooperative transitions were detected in PVF. The higher temperature one at ca. 45°C is the glass transition, as is well known in the literature. More information is needed to confirm the molecular origin and the effects of crystallinity and chemical structure on the low-temperature cooperative transition in PVF. © 1996 John Wiley & Sons, Inc.     

Low-temperature relaxations in styrene–crosslinked polyester networks

Two low-temperature dynamic mechanical relaxations have been observed in networks formed by copolymerization of poly(1,2-propylene fumarate) and poly(1,2-propylene phthalate fumarate) with styrene. The γ relaxation which occurs around ?100°C (1 Hz) is induced by small amounts of water, while the broad γ′ relaxation is reduced in height by the presence of water. Neither xylene nor 1,2-propylene glycol induced a γ relaxation. The γ relaxation was ascribed to motions involving a fumarate ester group–water complex.     

Nuclear magnetic relaxation and molecular motion in poly(vinylidine fluoride)

Pulsed NMR T₁, T₂, and T_1ρ measurements are reported for poly(vinylidine fluoride) (PVF₂). The results demonstrate clearly the presence of four relaxation processes, three amorphous and one crystalline. The α relaxation is undoubtedly a crystalline one, while β and γ are both amorphous, in agreement with earlier conclusions from dielectric and dynamic mechanical measurements. The fourth relaxation (β′) observed initially in the mechanical measurements of Kakutani, but undetected in dielectric experiments, has been confirmed in our results and the process is described by an activation energy of 15.1 kcl/mole. Motion of folds on the surface of crystal lamellae is deemed to be the responsible mechanism for the β′ relaxation. Two models have been considered in the interpretation of the α process; rotation of crystalline chains in the vicinity of defects and rotational oscillation of restricted amplitude of all crystalline chains about the main chain axes. Rotation of amorphous chains is a possible mechanism for the γ process while motions of a general nature are responsible for the β relaxation. Our experimental results again indicate that spin diffusion plays an important role in the overall NMR response of the polymer.     

Characterization of annealed isotactic polypropylene in the solid state by 2D time‐domain 1H NMR

Two‐dimensional time‐domain ¹H NMR was used to investigate annealed isotactic polypropylene in the solid phase. The spin–lattice relaxation in the laboratory frame and in the rotating frame were correlated with the shape of the free induction decay to identify and characterize relaxation components over the temperature range −120 to 120 °C. Several phase transitions were observed, and three distinct solid phases, with different chain mobilities, were detected. Two of these phases were identified as regions with different mobilities within the crystalline phase. The third phase was characterized by a high degree of isotropy in molecular motion. This phase, identified as the amorphous phase, appeared as the polymer was heated above a low‐temperature (−45 °C) phase transition. All transitions observed at higher temperatures occurred exclusively in this phase. About one‐third of the polymer chains reside between crystalline lamellae, whereas the majority form amorphous regions outside fibrils of multilamellar structure. Furthermore, the glass‐to‐rubber transition, occurring above −15 °C, consists of three stages. During the first stage, between −15 °C and 15 °C, regions with an increased segment mobility (labeled intermediate phase) appear gradually within the amorphous phase. At 15 °C, the intermediate phase consists of ∼10% of the polymer units, or one‐third of the polymer units constituting the amorphous phase. Between 15 °C and 25 °C, the intermediate phase increases rapidly to 18%. This is associated with the appearance of semiliquid and liquid regions, likely within the intermediate phase. Polymer chain segments (and possibly entire chains) involved in the liquidlike phases exhibit heterogeneous molecular motion with a correlation frequency higher than 10⁶ Hz. These two stages of glass‐to‐rubber transition occur within amorphous regions outside multilamellar structures. The third stage of the glass transition, appearing above 70 °C, is associated with the upper glass transition and occurs within the interlamellar amorphous phase. Finally, on a timescale of 100 ms or less, spin diffusion does not couple the amorphous regions outside fibrils with crystalline and amorphous regions within multilamellar fibrils. However, on a timescale of hundreds of milliseconds to seconds, all different regions within isotactic polypropylene are partially coupled. It is proposed that the relative magnitude of the crystalline magnetization, as observed in the T_1ρ experiment, is a good measure of polymer crystallinity. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2487–2506, 2000     

Influence of oxycycloaliphatic groups in the relaxation behavior of acrylic polymers

A comparative study on the mechanical and dielectric relaxation behavior of poly(5‐acryloxymethyl‐5‐methyl‐1,3‐dioxacyclohexane) (PAMMD), poly(5‐acryloxymethyl‐5‐ethyl‐1,3‐dioxacyclohexane) (PAMED), and poly(5‐methacryloxymethyl‐5‐ethyl‐1,3‐dioxacyclohexane) (PMAMED) is reported. The isochrones representing the mechanical and dielectric losses present prominent mechanical and dielectric β relaxations located at nearly the same temperature, approximately −80°C at 1 Hz, followed by ostensible glass–rubber or α relaxations centered in the neighborhood of 27, 30, and 125°C for PAMMD, PAMED, and PMAMED, respectively, at the same frequency. The values of the activation energy of the β dielectric relaxations of these polymers lie in the vicinity of 10 kcal mol⁻¹, ∼ 2 kcal mol⁻¹ lower than those corresponding to the mechanical relaxations. As usual, the temperature dependence of the mean‐relaxation times associated with both the dielectric and mechanical α relaxations is described by the Vogel–Fulcher–Tammann–Hesse (VFTH) equation. The dielectric relaxation spectra of PAMED and PAMMD present in the frequency domain, at temperatures slightly higher than T_g, the α and β relaxations at low and high frequencies, respectively. The high conductive contributions to the α relaxation of PMAMED preclude the possibility of isolating the dipolar component of this relaxation in this polymer. Attempts are made to estimate the temperature at which the α and β absorptions merge together to form the αβ relaxation in PAMMD and PAMED. Molecular Dynamics (MD) results, together with a comparative analysis of the spectra of several polymers, lead to the conclusion that flipping motions of the 1,3‐dioxacyclohexane ring may not be exclusively responsible for the β‐prominent relaxations that polymers containing dioxane and cyclohexane pendant groups in their structure present, as it is often assumed. The diffusion coefficient of ionic species, responsible for the high conductivity exhibited by these polymers in the α relaxation, is semiquantitatively calculated using a theory that assumes that this process arises from MWS effects, taking place in the bulk, combined with Nernst–Planckian electrodynamic effects, due to interfacial polarization in the films. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2486–2498, 1999