Dielectric relaxation studies on water absorption of ethylene ionomers

Yano, Shinichi; Tadano, Kenji; Nagao, Nobuaki; Kutsumizu, Shoichi; Tachino, Hitoshi; Hirasawa, Eisaku

doi:10.1021/ma00052a015

Cited by 32 publications

(42 citation statements)

References 2 publications

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Section: Introductionmentioning

confidence: 99%

“…Ethylene ionomers are copolymers consisting of methylene sequences as nonpolar segments and a small amount of methacrylic acid or acrylic acid residues as ionic units 1–24. It is well known that the ionic groups are partially or fully neutralized by metal ions such as Zn 2+ , Na + , Ca 2+ , Cu 2+ , or Mn 2+ 1–26. Because information about the structure and dynamics of ethylene ionomers is indispensable to an understanding of their mechanical, thermal, and other important physical properties, many investigations have been performed with differential scanning calorimetry (DSC),2, 3, 8, 10, 11, 13, 14, 17, 18 X‐ray diffractrometry,2–4, 13, 15, 18, 20, 23, 25, 26 Raman spectroscopy,5, 19 infrared (IR) spectroscopy,7, 8, 13, 19, 22, 24 electron spin resonance spectroscopy,12 dynamic mechanical analysis,13, 14, 17 and dielectric relaxation measurements 13, 16…”

Section: Introductionmentioning

confidence: 99%

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Controls exerted by the Aib residue: Helix formation and helix reversal This article is a US Government work and, as such, is in the public domain in the United States of America.

Karle

2001

Biopolymers

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Background Digital time‐lapse microscopy using Nomarski‐DIC requires that an autofocusing system adapt to changes in cell shape, size, and position while contending with drift, noise, and hysteresis in the microscope and imager. We have designed and implemented an autofocusing system that tracks subjects under dynamic conditions and maintains focus within a threshold of discriminability. Methods With the use of proven and novel algorithms for autofocusing in Nomarski, we performed “virtual” experiments on recorded image stacks to simulate drift and sudden displacements and test the search algorithm response. Results We found that combining a simple [1, −1] contrast function with an adaptive “warmer–colder” focusing algorithm yields a reasonable compromise between focusing precision and noise tolerance. This method was implemented to record growth kinetics of yeast cells in single and multiple fields of view over several hours. Conclusions We have implemented a robust digital autofocus that maintains focus on optically complex samples imaged at high resolution. The tolerance of this system of drift and vibration suggests that it is a practical system for time‐lapse imaging in many biological applications. Cytometry 49:159–169, 2002. © 2002 Wiley‐Liss, Inc.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Controls exerted by the Aib residue: Helix formation and helix reversal This article is a US Government work and, as such, is in the public domain in the United States of America.

Karle

2001

Biopolymers

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“…At 170 K, T 1 is 39.5 ms, which decreases quickly to 7.7 ms at 220 K. Since motion-induced spin-lattice relaxation is most effective for motions with frequency approaching the Larmor frequency, it is too fast to be detected by the transverse relaxation which has the time scale of a few hundred microseconds. The onset of this NMR-detected fast motion of water molecules could eventually lead to other mode of motions of water molecules, such as those detected by dielectric loss measurement, 21 which contributes further to motional narrowing. Figure 7 shows the Hahn-echo decay curves of the quenched sample at 260, 303, and 316 K, which are the characteristic temperatures over the range of the dramatic line narrowing.…”

Section: S(2t)mentioning

confidence: 99%

NMR Study of Structure and Dynamics of Ionic Multiplets in Ethylene−Methacrylic Acid Ionomers

Jia

Kleinhammes

2005

Macromolecules

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Structural and dynamical properties of ionic multiplets in poly(ethylene-co-methacrylic acid) ionomer neutralized with Na ions were studied by 23 Na nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). It was found that the low-temperature peak in DSC spectra is affected by relaxation, compression, and hydration and is related to structure in proximity to ionic multiplets, instead of multiplets themselves. The distance between Na ions in ionic multiplet was determined on the basis of a second moment measurement, suggesting that multiplets are composed of close-packed Na + -O -ionic pairs. Motional narrowing of 23 Na NMR line width and transverse relaxation measurement indicate that the time scale of motion of Na or its surrounding is on the order of a few hundred microseconds near room temperature. IntroductionIonomers derived from neutralization of ethylene/ methacrylic acid (E/MAA) copolymer, known as Surlyn, possess unique mechanical, rheological, and thermal properties 1-3 as well as the intriguing property of selfhealing. 4,5 These ionomers contain typically 15 mol % or less MAA which are partially neutralized with metal cations, 6-9 such as Zn 2+ and Na + . It is believed that aggregation of ionic pairs, such as -O --Na + , plays a crucial role in determining the unique properties of Surlyn. 1-3 Many tools have been used in studying the microstructure of Surlyn, including small-angle X-ray scattering (SAXS), 10-13 differential scanning calorimetry (DSC), [1][2][3]8,12,13 infrared spectroscopy (IR), 12 and nuclear magnetic resonance (NMR). 1,8 Scattering studies such as SAXS indicate that ionic pairs attract each other forming aggregates, called multiplets. 15 It is generally accepted that there are three regions in Surlyn: polyethylene crystalline lamellae, amorphous matrix, and multiplets of ionic pairs. The formation of ionic multiplets is believed to have a profound influence on the mechanical, thermal, and other physical and chemical properties. Previous DSC studies showed that two endothermic peaks are present upon heating of structurally relaxed (aged) Surlyn. The higher temperature peak, around 90°C, is attributed to the melting of polyethylene crystalline lamellae. 2,8,12,16 The identity of the low-temperature peak around 50°C remains unclear. This peak is absent in samples immediately after cooling from the melt and recovers after a certain period of structural relaxation at room temperature. 2,8,12,16 It was found that this low-temperature peak is also affected by hydration 14 and stretching. 13 One of the proposed explanations is the order-disorder transition of the ionic multiplet. 2,16 Others suggest that this peak is associated with the melting of imperfect crystallites of short segment polyethylene or changes occurring in the region surrounding the ionic multiplet rather than the ionic multiplet itself. 13 NMR is a sensitive probe of local structures and dynamics. 23 Na NMR provides a natural probe of the structure and dynamics of ionic

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“…The effect of humidity or temperature on the structure of ionomers is also of interest. Humidity effects on the structure of ionomers have been reported in a dielectric dispersion study,6 extended X‐ray absorption fine structure spectroscopy studies,7, 8 and an infrared study 8. The effect of water vapor on the structure of ionic aggregates is quite interesting with respect to both swelling and affinity for ionomers.…”

Section: Introductionmentioning

confidence: 96%

“…It is important to clarify the structure of ionic aggregates to understand their effect on physical properties. Recently, there has been much attention addressing the structure of ionic aggregates of ionomers 2–8. There are many reports on small‐angle X‐ray scattering (SAXS) studies of ionomers 2–5.…”

Section: Introductionmentioning

confidence: 99%

Structure of ionic aggregates of ionomers. II. Effect of humidity and temperature on ethylene and styrene ionomers

Tsujita

Yasuda

Kinoshita

et al. 2002

J Polym Sci B Polym Phys

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Small‐angle X‐ray scattering profiles of ethylene and styrene ionomers were studied to clarify the structure of ionic aggregates as a function of humidity or temperature. The intensity and position of ionic cluster peaks were observed for ionomers with a certain degree of neutralization. The intensity of the ionic cluster peak for the ethylene ionomer increased with increasing relative humidity, but it decreased for the styrene ionomer. With increasing humidity, the position of the ionic cluster peak shifted to smaller angles for both ionomers. The size of the ionic aggregates and the closest approach distance between the aggregates were analyzed, and the results varied with humidity for both ionomers. The size did not vary markedly with a change in temperature, whereas the closest approach distance and number of ionic aggregates changed slightly with the melting temperature of the ethylene ionomer and the glass‐transition temperature of the styrene ionomer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 831–839, 2002

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Dielectric relaxation studies on water absorption of ethylene ionomers

Cited by 32 publications

References 2 publications

Controls exerted by the Aib residue: Helix formation and helix reversal This article is a US Government work and, as such, is in the public domain in the United States of America.

Controls exerted by the Aib residue: Helix formation and helix reversal This article is a US Government work and, as such, is in the public domain in the United States of America.

NMR Study of Structure and Dynamics of Ionic Multiplets in Ethylene−Methacrylic Acid Ionomers

Structure of ionic aggregates of ionomers. II. Effect of humidity and temperature on ethylene and styrene ionomers

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