Influence of change in ether structure on the low temperature dielectric relaxation of some poly(ether imide)

Broad band dielectric relaxation spectra are reported on a range of polymers created by varying the ether segment in a series of poly(ether imide)s. Changes in the structure allow the effects of steric constraints on the local conformational dynamics of the polymer chain to be explored. These changes have a significant effect on the glass transition temperatures of these polymers which range from 245 to over 420°C. In contrast, the low temperature dielectric relaxation behavior of these polymers is very similar and is attributed to cooperative local oscillatory—librational motions. Changes in the stereochemistry effect the amplitude, activation energy for the relaxation process, the packing chain density, and values of the high frequency limiting permittivity, ε_∞′. This latter parameter is sensitive to the extent of dipole induced dipole and π‐π electron interactions and is influenced by the packing density. The magnitude of ε_∞′ is a very important parameter in determining the suitability of poly(imide)s for electrical applications. The magnitude of ε_∞′ increases with the density; however, deviations from this general trend are observed when large nonpolar groups inhibit the interaction of neighboring chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41191.     

A relaxational and conductive study on two poly(ether imide)s

A study of the relaxations and the conductivity of poly(ether imide) (PEI) ULTEM 5000 was carried out. The results were compared with the ones obtained in a previous study of PEI ULTEM 1000. The glass transition temperature was determined by differential scanning calorimetry (DSC). Then, the relaxations of PEI ULTEM 5000 using the thermally stimulated depolarization current technique (TSDC) on conventionally polarized electrets were studied. Owing to the interesting structure indicated by this technique a more detailed analysis of the β relaxation was done using window polarization (WP). It was possible to isolate 7 subrelaxations that we related to their counterparts in PEI ULTEM 1000. WP was also used to compare, one by one, the other relaxations that both materials present. The analysis of the ρ relaxation showed that the space trapping capability is stronger in PEI ULTEM 5000. The role of conductivity was analyzed using open circuit polarized samples and, more quantitatively, using dielectric analysis (DEA) and the dielectric modulus formalism. DEA and dynamic mechanical thermal analysis (DMTA) were also used to obtain information about the polar relaxations, complementary to that obtained by TSDC. Copyright © 2004 Society of Chemical Industry     

Miscibility and crystallization behavior of poly(ether ether ketone ketone)/poly(ether imide) blends

The miscibility and crystallization behavior of poly(ether ether ketone ketone) (PEEKK)/poly(ether imide) (PEI) blends prepared by melt‐mixing were investigated by differential scanning calorimetry. The blends showed a single glass transition temperature, which increased with increasing PEI content, indicating that PEEKK and PEI are completely miscible in the amorphous phase over the studied composition range (weight ratio: 90/10–60/40). The cold crystallization of PEEKK blended with PEI was retarded by the presence of PEI, as is apparent from the increase of the cold crystallization temperature and decrease of the normalized crystallinity for the samples anealed at 300°C with increasing PEI content. Although the depression of the apparent melting temperature of PEEKK blended with PEI was observed, there was no evidence of depression in the equilibrium melting temperature. The analysis of the isothermal crystallization at 313–321°C from the melt of PEEKK/PEI (100/0, 90/10, and 80/20) blends suggested that the retardation of crystallization of PEEKK is caused by the increase of the crystal surface free energy in addition to the decrease of the mobility by blending PEI with a high glass transition temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 769–775, 2001     

Blends of poly(ether imide) and an aromatic poly(ether amide): Phase behavior and CO2 transport properties

Blends of poly(ether imide) (PEI, Ultem 1000) and an aromatic poly(ether amide) were studied. Although homogeneous or heterogeneous blends can be obtained depending on the blend preparation method, the inherent miscibility of the mixture was finally established. The so-called enthalpy relaxation method was used to detect one or two glass transition temperatures in the blends in spite of the similarity of the pure component transitions. Fourier transform infrared analysis provided additional evidence of the specific interactions, which could be in the origin of the miscibility. A preliminary study of the influence of the homogeneity level in the transport properties of the blend films was also undertaken. Carbon dioxide at 1 bar was used as a penetrant. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2141–2149, 1998     

Dielectric relaxation of poly(tetrafluoroethylene–perfluorovinyl ether) films

Dielectric constant and dielectric loss have been studied for poly(tetrafluoroethylene–perfluorovinyl ether) (PFA) films over a wide temperature range in the frequency range 0.1–100 kHz. Two relaxation peaks were observed, one at room temperature (α_a-relaxation) and the other in the range 170–140 K (β-relaxation), with activation energies of 143·2 and 16·4 kcal/mol, respectively. The β-absorption is attributed to the short segmental local mode motion of the main chains. The α_a-relaxation can be interpreted as due to large-scale conformational rearrangement. The Cole–Cole diagrams are given at different temperatures and the distribution parameters (ϵ₀–ϵ_∞) and (1–α) of the relaxation times were calculated. The X-ray diffraction pattern of PFA shows both a diffuse halo and sharp reflections, characteristic of amorphous and crystalline phases of conventional semicrystalline polymers. Also, no evidence of crystallinity in the films due to thermal treatment during dielectric measurements was observed. IR spectra revealed the absence of any new peaks after the heat treatment.     

Thermal properties of melt‐blended poly(ether ether ketone) and poly(ether imide)

The thermal properties of blends of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) prepared by screw extrusion were investigated by differential scanning calorimetry. From the thermal analysis of amorphous PEEK–PEI blends which were obtained by quenching in liquid nitrogen, a single glass transition temperature (T_g) and negative excess heat capacities of mixing were observed with the blend composition. These results indicate that there is a favorable interaction between the PEEK and PEI in the blends and that there is miscibility between the two components. From the Lu and Weiss equation and a modified equation from this work, the polymer–polymer interaction parameter (χ₁₂) of the amorphous PEEK–PEI blends was calculated and found to range from −0.058 to −0.196 for the extruded blends with the compositions. The χ₁₂ values calculated from this work appear to be lower than the χ₁₂ values calculated from the Lu and Weiss equation. The χ₁₂ values calculated from the T_g method both ways decreased with increase of the PEI weight fraction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 733–739, 1999     

Scope in the synthesis and properties of poly(ether imide)s

This paper reviews methods of synthesis of dianhydrides for use in poly(ether imide) syntheses. It discusses the synthesis of new dianhydrides from alkyl-substituted diols, catechol and its derivatives and dihydroxynaphthalenes and the synthesis of new poly(ether imide)s from them. The major features of the properties of these groups of polymers, especially those of highly processable poly(ether imide)s, are discussed and potential applications are considered.     

Compatibility studies of sulfonated poly(ether ether ketone)–poly(ether imide)–polycarbonate ternary blends

Binary blends of the sulfonated poly(ether ether ketone) (SPEEK)–poly(ether imide) (PEI) and SPEEK–polycarbonate (PC), and ternary blends of the SPEEK–PEI–PC, were investigated by differential scanning calorimetry. SPEEK was obtained by sulfonation of poly(ether ether ketone) using 95% sulfuric acid. From the thermal analysis of the SPEEK–PEI blends, single glass transition temperature (T_g) was observed at all the blend composition. For the SPEEK–PC blends, double T_gs were observed. From the results of thermal analysis, it is suggested that the SPEEK–PEI blends are miscible and the SPEEK–PC blends are immiscible. Polymer–polymer interaction parameter (χ₁₂) of the SPEEK–PEI blends was calculated from the modified Lu and Weiss equation, and found to range from −0.011 to −0.825 with the blend composition. For the SPEEK–PC blends, the χ₁₂ values were calculated from the modified Flory–Huggins equation, and found to range from 0.191 to 0.272 with the blend composition. For the SPEEK–PEI–PC ternary blends, phase separation regions that showed two T_gs were found to be consistent with the spinodal curves calculated from the χ₁₂ values of the three binary blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2488–2494, 2000     

Dielectric relaxation behaviour of poly(cyclobutyl methacrylate)s

Dielectric behaviour of two poly(methacrylate)s with cyclobutyl groups in the side‐chains has been studied. This investigation was performed by determining the dielectric permittivity and loss in terms of frequency and temperature for poly(cyclobutyl methacrylate) (PCBuM) and poly(cyclobutylmethyl methacrylate) (PCBuMM). Dynamic dielectric measurements show sub‐glass relaxations, probably due to motions in the lateral chain, including the cyclobutyl ring. The effect of the insertion of a flexible spacer group into the side‐chain is also analyzed. The α relaxations were analyzed in terms of the Havriliak–Negami equation and the free volume theory tested according to the Vogel–Fulcher–Tamman–Hesse equation. The conductive and interfacial phenomena were studied by hopping and MacDonald–Coelho models. © 2002 Society of Chemical Industry     

Organosoluble poly(ether imide)s from phthalimidine based and trifluoromethyl substituted bis(ether amine)

A series of new organosoluble and optically transparent poly(ether imide)s (PEIs) were synthesized by the polycondensation of trifluoromethyl substituted and phthalimidine cardo group based bis(ether amine), 3,3‐bis‐[4‐{2′‐trifluoromethyl 4′‐(4″‐aminophenyl)phenoxy}phenyl]‐2‐phenyl‐2, 3‐dihydro‐isoindole‐1‐one with different fluorinated and non‐fluorinated aromatic dianhydrides (2a–e). All the PEIs were well characterized by elemental analysis, NMR, FTIR spectroscopy, and gel permeation chromatography (GPC). The synthesized PEIs showed moderate to high inherent viscosity 0.41–0.61 dL/g and excellent solubility at room temperature in different organic solvents. All the transparent yellow films showed cut‐off length upto 425 nm. They exhibited high tensile strengths upto 98 MPa, excellent thermostability upto 554°C for 5% weight loss, high glass transition temperature upto 327°C, and water uptake value less than 0.6%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of novel adamantane‐based copoly(aryl ether ketone)s with low dielectric constants

A series of novel adamantane‐based copoly(aryl ether ketone)s (PAEK‐CF₃‐Ad) with low dielectric constants were prepared by post‐amidation of copoly(aryl ether ketone)s containing (3‐trifluoromethyl)phenyl and carboxyl groups with 4‐adamantylaniline. Compared with the preparation of adamantane‐containing poly(aryl ether ketone)s by direct polymerization of adamantyl‐substituted monomers, this side‐chain grafting method avoids various problems, such as high polymerization temperature and the difficult polymerization of adamantyl‐substituted monomers. The dielectric, thermal and mechanical properties of the synthesized PAEK‐CF₃‐Ad were characterized using a precision impedance analyzer, differential scanning calorimetry and thermogravimetric analysis, and a universal tester, respectively. The results indicate that PAEK‐CF₃‐Ad films exhibited low dielectric constants ranging from 2.33 to 2.65 at 1 MHz due to the introduction of the adamantyl groups. The synthesized PAEK‐CF₃‐Ad copolymers exhibited good thermal and mechanical properties. © 2013 Society of Chemical Industry     

Processable and colorless fluorinated poly(ether imide)s based on an isopropylidene‐containing bis(ether anhydride) and various aromatic bis(ether amine)s bearing trifluoromethyl groups

A series of novel organosoluble and light‐colored fluorinated poly(ether imide)s (PEIs) ( IV ) having inherent viscosities of 0.43–0.59 dL/g were prepared from 4,4′‐[1,4‐phenylenbis(isopropylidene‐1,4‐phenyleneoxy)]diphthalic anhydride ( I ) and various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal and chemical imidization of poly(amic acid) precursors. These PEIs showed excellent solubility in many organic solvents and could be solution‐cast into transparent and tough films. These films were essentially colorless, with an UV–visible absorption edge of 361–375 nm and a very low b* value (a yellowness index) of 15.3–17.0. They also showed good thermal stability with glass‐transition temperature of 191–248°C, 10% weight loss temperature in excess of 494°C, and char yields at 800°C in nitrogen more than 39%. The thermally cured PEI films showed good mechanical properties with tensile strengths of 83–96 MPa, elongations at break of 8–11%, and initial moduli of 1.7–2.0 GPa. They possessed lower dielectric constants of 3.25–3.72 (1 MHz). In comparison with the V series nonfluorinated PEIs, the IV series showed better solubility, lower color intensity, and lower dielectric constants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 620–628, 2007     

Synthesis and characterization of highly soluble poly(ether imide)s containing indane moieties in the main chain

A new indane containing unsymmetrical diamine monomer ( 3 ) was synthesized. This diamine monomer leads to a number of novel semifluorinated poly (ether imide)s when reacted with different commercially available dianhydrides like benzene‐1,2,4,5‐tetracarboxylic dianhydride (PMDA), benzophenone‐3,3′, 4,4′‐tetracarboxylic dianhydride (BTDA), 4,4′‐(hexafluoro‐isopropylidene)diphthalic anhydride (6FDA), 4,4′‐oxydiphthalic anhydride (ODPA), and 4,4′‐(4,4′‐Isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) by thermal imidization route. All the poly(ether imide)s showed excellent solubility in several organic solvents such as N‐methylpyrrolidone (NMP), N,N‐dimethylformamide (DMF), N,N‐dimethylacetamide (DMAc), tetrahydrofuran (THF), chloroform (CHCl₃) and dichloromethane (DCM) at room temperature. These light yellow poly (ether imide)s showed very low water absorption (0.19–0.30%) and very good optical transparency. Wide angle X‐ray diffraction measurements revealed that these polymers were amorphous in nature. The polymers exhibited high thermal stability up to 526°C in nitrogen with 5% weight loss, and high glass transition temperature up to 265°C. The polymers exhibited high tensile strength up to 85 MPa, modulus up to 2.5 GPa and elongation at break up to 38%, depending on the exact polymer structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Adhesion property of sulfonated poly(arylene ether sulfone)s

Sulfonated poly(arylene ether sulfone)s (S‐PESs) were synthesized from sulfonated 4,4′‐dichlorodiphenylsulfone (S‐DCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS), and 4,4′‐biphenol through variations in the molar ratio of S‐DCDPS to DCDPS from 10/90 to 40/60. The S‐PES sodium form was characterized with Fourier transform infrared, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis, and the intrinsic viscosity and solubility were also evaluated. The sodium form was then subjected to acidification by immersion in 1.5M HCl for 24 h at room temperature, which was followed by washing with deionized water. The S‐PES adhesive properties were measured with single laboratory shear samples with aluminum alloys, and the failure mode was investigated. The synthesized S‐PESs exhibited increased glass‐transition temperatures with increased S‐DCDPS/DCDPS ratios; their acid forms provided much lower glass‐transition temperatures than their sodium forms. In addition, the S‐PES sodium form exhibited a high intrinsic viscosity, which indicated a high molecular weight. The S‐PES acid form exhibited an adhesion strength similar to that of the sodium form, and the single‐lap‐shear strength increased with 10% S‐PES and then decreased with 20, 30, and 40% S‐PES. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1211–1218, 2004     

Solvent effects on microwave dielectric relaxation in poly(ethylene glycols)

This paper reports the results of a systematic study of microwave dielectric relaxation times of poly(ethylene glycols), average molecular weight 200–9000, in dilute solutions of benzene at 9·83GHz. These results are compared with the values of relaxation times obtained earlier in carbon tetrachloride solutions. This shows that the average relaxation times τ₀ and the relaxation time corresponding to segmental reorientation τ₁ are influenced by the solvent environment. The variation in chain flexibility in these polymers with the increase in degree of polymerization and formation of intra- and inter-molecular hydrogen bonding in benzene and carbon tetrachloride solutions is discussed with the help of relaxation data. The relaxation time τ₂ corresponding to group rotations has been determined. It is found that the τ₂ value is independent of solvent environment and degree of polymerization, and may be attributed to the rotation of chain −OH end-groups around the C−O bonds in dynamic equilibrium, with the formation of a five-membered ring due to intra-molecular hydrogen bonding at the end of the chain. © 1998 SCI.     

Preparation and properties of new thermally stable poly(ether imide amide)s

2,6‐Bis(4‐aminophenoxy)pyridine was prepared via reaction of 4‐aminophenol with 2,6‐dichloropyridine in the presence of potassium carbonate. Reaction of the diamine with two mol of trimellitic anhydride afforded a diacid with preformed imide structures. Poly(ether imide amide)s were prepared by polycondensation reactions of the diacid with different diamines in the presence of triphenyl phosphite. All the monomers and polymers were fully characterized and the physical properties of the polymers including solution viscosity, thermal stability, thermal behavior and solubility were studied. Thermal analysis data showed the polymers to have high thermal stability. Copyright © 2004 Society of Chemical Industry     

Flow-modified permittivity of solutions of poly(n-butyl isocyanate) and poly(n-hexyl isocyanate)

The dielectric behaviour of solutions of poly(n-butyl isocyanate) and poly(n-hexyl isocyanate) in flow have been examined, including, for the latter polymer, fractions of differing molecular weight. The data are analysed in terms of established theories for changes in the permittivity of solutions of rigid macromolecules undergoing shear and are critically compared to dielectrically based information obtained from studies of still solutions. Rotational diffusion coefficients and dipole moments have been measured and the influence of heterogeneity in molecular weight on flow-modified permittivity is examined. The results obtained support the view that the theories for the flow-modified permittivity of rigid macromolecules are generally satisfactory in providing rotational diffusion coefficients and resolved dipoles, but that the influence of molecular shape on the effect is not simply obtained when polydisperse material is involved.     

Microwave dielectric relaxation in binary mixtures of poly(ethylene glycols) in solution

The average relaxation time τ₀, relaxation times corresponding to segmental motion τ₁ and group rotations τ₂, of a series of binary mixtures of poly(ethylene glycols) (PEG 200+PEG 300, PEG 400+PEG 600, PEG 1500+PEG 4000, PEG 6000+PEG 9000, PEG 200+PEG 1500, PEG 300+PEG 4000, PEG 400+PEG 6000 and PEG 600+PEG 9000) have been carried out in dilute solutions of benzene and carbon tetrachloride at 9·83GHz. The effect on chain flexibility due to inter- and intra-molecular association in these binary mixtures is discussed by comparing relaxation times of these mixtures with their individual relaxation times in solution. It is inferred that the extent of hydrogen bonding in different binary mixtures is not similar and is influenced by solvent environment, but there is correlation between τ₀ and τ₁ values in all these binary mixtures, which may be because of hydrogen bonding. The observed τ₂ values in all these mixtures suggests that the chain-ends remain excluded from the intermolecular association and τ₂ is independent of the polymer constituents of the mixture and solvent. It is also equal to the τ₂ values of the individual polymers. © 1998 SCI.     

Synthesis and characterization of organo‐soluble poly(ether ether ketone)s and poly(ether ether ketone ketone)s containing pendant pentadecyl chains

Poly(ether ether ketone)s and poly(ether ether ketone ketone)s containing pendant pentadecyl chains were synthesized by polycondensation of each of the two bisphenol monomers viz, 1,1,1‐[bis(4‐hydroxyphenyl)‐4′‐pentadecylphenyl]ethane and 1,1‐bis(4‐hydroxyphenyl)‐3‐pentadecyl cyclohexane with activated aromatic dihalides namely, 4,4′‐difluorobenzophenone, and 1,3‐bis(4‐fluorobenzoyl)benzene in a solvent mixture of N,N‐dimethylacetamide and toluene, in the presence of anhydrous potassium carbonate. Polymers were isolated as white fibrous materials with inherent viscosities and number average molecular weights in the range 0.70–1.27 dL g^?1 and 76,620–1,36,720, respectively. Poly(ether ether ketone)s and poly(ether ether ketone ketone)s were found to be soluble at room temperature in organic solvents such as chloroform, dichloromethane, tetrahydrofuran, and pyridine and could be cast into tough, transparent, and flexible films from their solutions in chloroform. Wide angle X‐ray diffraction patterns exhibited a broad halo at around 2θ = ～ 19° indicating that the polymers containing pentadecyl chains were amorphous in nature. In the small‐angle region, diffuse reflections of a typically layered structures resulting from the packing of pentadecyl side chains were observed. The temperature at 10% weight loss, obtained from TG curves, for poly(ether ether ketone)s and poly(ether ether ketone ketone)s were in the range 416–459°C, indicating their good thermal stability. A substantial drop in glass transition temperatures (68–78°C) was observed for poly(ether ether ketone)s and poly(ether ether ketone ketone)s due to “internal plasticization” effect of flexible pendant pentadecyl chains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011