Dielectric Normal Mode Process Research Articles

Molecular dynamics of poly (oxybutylene)s confined in pores of Vycor glass

We have investigated the relaxation dynamics of poly (oxybutylene), POB, chains of various lengths, with different end groups (OH and CH3) in bulk and in confinement using dielectric relaxation spectroscopy. It is known that POB chains exhibit, apart from the segmental (main) relaxation process, the dielectric normal mode process which reflects the global chain motions. The comparative study of OH- and methyl-ended POB chains in bulk reveals the marked effect of association of hydroxyl end groups and indicates that the decrease in the density of the methylated specimens results in the acceleration of both relaxation processes, main and normal mode relaxations. For the confined POB chains the data indicate that the segmental relaxation process becomes faster (the effect being more pronounced for the methylated POB chains). A decrease in Tg of about 8K for the methyl- and 2K for OH-ended POB chains is estimated. Regarding the average relaxation rates of the normal mode process our data indicate that global chain mobility is not affected by the confinement.

Dielectric normal mode process of bifurcated linear cis-polyisoprene

The dielectric normal mode process of bifurcated linear cis-polyisoprenes (PI), which are composed of two linear PI arms connected in a head-to-head fashion and have dipoles along the chain contour inverted once at the center, was compared with that of regular linear PIs without dipole inversion, and also with that of six-arm star PIs with dipoles diverging from the center to the arm ends

Dielectric normal mode process in binary blends of polyisoprene. 1. Excluded volume effect in undiluted binary blends

Determination de la distance bout a bout quadratique moyenne d'un cis-polyisoprene monodisperse a masse moleculaire elevee melange a 0,5-5% avec un cis-PI a masse moleculaire faible. Dans les melanges dilues, le cis-PI a une conformation allongee

Dielectric normal mode process in binary blends of polyisoprene. 2. Dynamic behavior

Dielectric normal mode process in binary blends of polyisoprene. 2. Dynamic behavior

Model Calculation for Viscoelastic and Dielectric Relaxation Functions of Non-Entangled Star Chains with Arm Length Distribution

Based on Rouse-Ham dynamics, we examined viscoelastic and dielectric relaxation functions of unentangled model star chains of f arms with and without arm-length distribution. We assumed that each arm possesses the dipole moment aligned in the same direction along the chain contour from the center to the arm end, and thus exhibits the dielectric normal mode process related to center-to-end vector fluctuation of arms. The model calculation suggested that the arm-length distribution influences the mode distribution of the dielectric normal mode relaxation more strongly as compared to that of the viscoelastic relaxation that reflects the orientational anisotropy of the whole segments of the star molecules. This difference is due to the difference in the contribution of the Rouse-Ham eigenfunctions to these two relaxation functions.

Dielectric relaxation in concentrated solutions of cis-polyisoprene. Part 3.—Relationship between friction coefficient for dielectric normal-mode process and local segmental motions

The data of dielectric normal mode process (αI) and the segmental mode process (αII) reported in parts 1 and 2 of this series were analysed to find a relationship between the friction coefficient ζ for the normal mode process and the relaxation time τs for the segmental mode process. Assuming τs proportional to ζ, we attempted to superpose the τnvs. molecular weight Mw plots for solutions with different concentrations C. From the vertical and horizontal shift factors, we found that the monomeric friction coefficient ζm is approximately proportional to C2τs. To explain this result, we assumed that the effective size for the segmental motions expands with decreasing C. The molecular weight M0 for the unit of the segmental motion was estimated based on the computer simulation reported by Verdier and Stockmayer. The M0 was found to be 77 for bulk cis-PI and increased with decreasing C approximately in proportion to C–1.

Further investigation of the dielectric normal mode process in undiluted c i s-polyisoprene with narrow distribution of molecular weight

Dielectric relaxations in undiluted cis-polyisoprene (cis-PI) with narrow molecular-weight distribution were investigated. The normal mode process due to fluctuation of the end-to-end distance and the segmental mode process due to the local segmental motions were observed. The average relaxation time τn for the normal mode process was insensitive to the polydispersity Mw/Mn, but the width of the loss curve reflecting the distribution of the relaxation times increased with Mw/Mn. The slope of the double logarithmic plot of τn against Mw changed at the characteristic molecular weight Mc from 2.0 in the range Mw<Mc to 4.0±0.2 in the range Mw>Mc. It was found that although the half-width is nearly independent of Mw, the tail of the loss curve in the high frequency side broadens with increasing Mw. This indicates that by entanglement effects the distribution of the relaxation time for the normal mode process changes slightly. The segmental mode is found to be almost independent of the molecular weight and the polydispersity factor.

Dielectric normal mode process in semidilute and concentrated solutions of cis-polyisoprene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDielectric normal mode process in semidilute and concentrated solutions of cis-polyisopreneKeiichiro Adachi and Tadao KotakaCite this: Macromolecules 1988, 21, 1, 157–164Publication Date (Print):January 1, 1988Publication History Published online1 May 2002Published inissue 1 January 1988https://doi.org/10.1021/ma00179a032RIGHTS & PERMISSIONSArticle Views158Altmetric-Citations52LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (937 KB) Get e-Alerts Get e-Alerts

Solution-crosslinked networks. 3. Dielectric normal mode process of guest polyisoprene in natural rubber networks

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolution-crosslinked networks. 3. Dielectric normal mode process of guest polyisoprene in natural rubber networksBeng Teik Poh, Keiichiro Adachi, and Tadao KotakaCite this: Macromolecules 1987, 20, 10, 2574–2579Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://doi.org/10.1021/ma00176a043RIGHTS & PERMISSIONSArticle Views142Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (701 KB) Get e-Alerts Get e-Alerts

Effect of entanglement on the dielectric normal mode process in solutions of cis-polyisoprene

Abstract Dielectric normal mode process due to the fluctuation of end-to-end vector of chain molecules is studied on solutions of cis-polyisoprene over a wide range of concentration from infinite dilution to the bulk state. It is found that with increasing concentration and molecular weight, the relaxation time for the normal mode process increases on account of entanglement. We compare the experimental results with the Rouse-Zimm theory and the dynamic scaling law proposed by de Gennes.

Dielectric normal mode process in dilute solutions of cis-polyisoprene

Relaxation dielectrique due a la fluctuation de la distance bout a bout de solutions dans le benzene et le dioxanne

Relaxation Processes and Dynamical Structure in Polymer Liquids

We review recent studies of dielectric relaxation and dynamical structure in solutions and melts of cis-polyisoprene (cis-PI) which exhibit dielectric normal mode process due to the fluctuation of end-to-end distance as well as the local segmental mode process. The influences of varying molecular weight, concentration, and solvent quality on the relaxation time for the normal mode process are discussed based on the bead-spring model and the tube model. The dielectric and mechanical relaxation spectra in bulk cis-PI are compared over a wide time scale covering both the wedge and box type spectral region. The relationship between the monomeric friction coefficient and the dielectric relaxation time for the segmental mode process is also discussed.

Dielectric Normal Mode Process in Semidilute and Concentrated Solutions of Poly(2,6-dichloro-1,4-phenylene oxide)

The dielectric normal mode process was investigated on semi-dilute and concentrated solutions of poly(2,6-dichloro-1,4-phenylene oxide)(PDCPO-M) in a good solvent, chlorobenzene, at 300 K. Four linear, short chain samples with molecular weight M less than 20×103, two nearly linear samples of intermediate M, and a high M, randomly branched sample (PDCPO-380) of M=380×103 were used. The dielectric relaxation time τ for 40 wt% solutions of the linear samples was approximately proportional to M2, indicating Rouse behavior of non-entangled chains. The loss curves of the PDCPO-17 solutions were symmetrical in shape, and the half width A increased slightly with increasing concentration C due presumably to the increase in the local friction constant ζ. On the other hand, for the branched, high M PDCPO-380 sample, its loss curve not only became broader with increasing C, but split into two peaks at about C=30 wt%. This is presumably because the relaxation time of longer branches of the sample were retarded more strongly by entanglement. From the relaxation strength, the mean square end-to-end distance ‹r2› was determined as a function of C for PDCPO-17 solutions. The slope of the log‹r2› vs. logC plot was approximately −0.08 in the range of 0.2<C<1.0. This value is much smaller than −0.25 expected from the scaling theory. This discrepancy may be attributed to the weak excluded volume effect for the low molecular weight sample.

Application of scaling laws to the dielectric normal mode process of cis-polyisoprene in solutions of infinite dilution to the bulk

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTApplication of scaling laws to the dielectric normal mode process of cis-polyisoprene in solutions of infinite dilution to the bulkKeiichiro Adachi, Hiroshi Okazaki, and Tadao KotakaCite this: Macromolecules 1985, 18, 9, 1687–1692Publication Date (Print):September 1, 1985Publication History Published online1 May 2002Published inissue 1 September 1985https://doi.org/10.1021/ma00151a008RIGHTS & PERMISSIONSArticle Views64Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (680 KB) Get e-Alerts Get e-Alerts

Effects of excluded volume and solvent polarity on the dielectric normal mode process in dilute solutions of poly(2,6-dichloro-1,4-phenylene oxide)

Effects of excluded volume and solvent polarity on the dielectric normal mode process in dilute solutions of poly(2,6-dichloro-1,4-phenylene oxide)

Dielectric normal mode process in undiluted cis-polyisoprene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDielectric normal mode process in undiluted cis-polyisopreneKeiichiro Adachi and Tadao KotakaCite this: Macromolecules 1985, 18, 3, 466–472Publication Date (Print):March 1, 1985Publication History Published online1 May 2002Published inissue 1 March 1985https://doi.org/10.1021/ma00145a028RIGHTS & PERMISSIONSArticle Views540Altmetric-Citations119LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (824 KB) Get e-Alerts Get e-Alerts

Dielectric normal mode process in dilute solutions of poly(2,6-dichloro-1,4-phenylene oxide)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDielectric normal mode process in dilute solutions of poly(2,6-dichloro-1,4-phenylene oxide)Keiichiro Adachi and Tadao KotakaCite this: Macromolecules 1983, 16, 12, 1936–1941Publication Date (Print):December 1, 1983Publication History Published online1 May 2002Published inissue 1 December 1983https://doi.org/10.1021/ma00246a025RIGHTS & PERMISSIONSArticle Views84Altmetric-Citations27LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (735 KB) Get e-Alerts Get e-Alerts