Dielectric studies of the methacrylate series. III. Poly‐<i>n</i>‐hexyl methacrylate. IV. Poly‐<i>n</i>‐octyl methacrylate

Strella, Stephen; Chinai, Suresh N.

doi:10.1002/pol.1958.1203112206

Cited by 19 publications

(8 citation statements)

References 3 publications

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“…Strella et al [15][16][17] showed that the dielectric loss function, cf'(w), for poly(alky1 methacrylates) changed shape with changing temperature. Thus, the time-temperature superposition principle could not be applied to the full dielectric loss data of poly(alky1 methacrylates) including PHMA.…”

Section: (3)mentioning

confidence: 99%

Photon correlation spectroscopy of bulk poly(n‐hexyl methacrylate) near the glass transition

Hwang

Patterson

Stevens

1996

J. Polym. Sci. B Polym. Phys.

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Slowly relaxing longitudinal density fluctuations in an optically perfect sample of bulk poly(n‐hexyl methacrylate) (PHMA) have been studied by photon correlation spectroscopy in the temperature range 10–36°C. The glass transition temperature for this sample was measured to be Tg = −3°C by differential scanning calorimetry. The optical purity of the sample was verified by Rayleigh‐Brillouin spectroscopy and the Landau‐Placzek ratio was observed to be 2.3 at 25°C. Light‐scattering relaxation functions were obtained over the time range 10−6‐1 s. The shape of the relaxation functions broadened as the temperature was lowered towards the glass transition. Quantitative analysis of the results was carried out using the Kohlrausch‐Williams‐Watts (KWW) function to obtain average relaxation times, 〈τ〉, and width parameters, β. The width parameter decreased from 0.43 to 0.21 over the temperature interval, as suggested by visual inspection. Average relaxation times shifted with temperature in a manner consistent with previous mechanical studies of the primary glass‐rubber relaxation in PHMA. The relaxation functions were also analyzed in terms of a distribution of relaxation rates, G(Γ). The calculated distributions were unimodal at all temperatures. The average relaxation times obtained from G(Γ) were in agreement with the KWW analysis, and the shape of the distribution broadened as the sample was cooled. The rate at which G(Γ) displayed a maximum correlated well with the corresponding frequency of maximum dielectric loss for PHMA. The temperature dependence of these two quantities could be reproduced with an Arrhenius activation energy of 21 Kcal/mol. A consistent picture of the molecular dynamics of PHMA near the glass transition requires a strong secondary relaxation process with a different temperature dependence from the primary glass‐rubber relaxation. The present results suggest that the behavior of PHMA is similar to the other poly(alkyl methacrylates). © 1996 John Wiley & Sons, Inc.

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Section: (3)mentioning

confidence: 99%

Photon correlation spectroscopy of bulk poly(n‐hexyl methacrylate) near the glass transition

Hwang

Patterson

Stevens

1996

J. Polym. Sci. B Polym. Phys.

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“…As usual, the polymethacrylate displays a higher T g than the corresponding polyacrylate . The existence of two T g values also has been observed in some poly( n ‐alkyl methacrylate)s with long side chains . The physical interpretation of this behaviour is related to the presence of different domains in which the dynamics are dominated either by the alkyl side chain or by the main chain.…”

Section: Resultsmentioning

confidence: 60%

Study of the dielectric relaxation of poly(phenylpropyl acrylate) and poly(phenylpropyl methacrylate): effect of slight differences in chemical structure

et al. 2015

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WileyOrtiz Serna, MP.; Sanchis Sánchez, MJ.; Redondo Foj, MB.; Carsí Rosique, M.; Díaz Calleja, R.; Leiva, A.; Gargallo, L.... (2015). Study of the dielectric relaxation of poly(phenylpropyl acrylate) and poly(phenylpropyl methacrylate): effect of slight differences in chemical structure. Polymer International. 64 (12) one glass-rubber transition (T g ) for the P3Ph1PA and two for the P3Ph1PM samples, which evidences the great effect of the methyl groups on the segmental motions of the polymer. Phenomenological analysis of the data has been carried out in order to establish the strength, width, and fragility parameters of the glass-rubber transitions. In the case of the P3Ph1PA, the strength was found to be larger than for the P3Ph1PM, pointing out that the methyl group disturbs the mobility. Conductive processes dominate the dielectric spectra at high temperatures and low frequencies.

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“…The motions that dominate dielectric loss behavior in PHMA are associated with the -relaxation. 15 For the lowest temperatures and shortest delay times, the correlation function and distribution of relaxation times shows an upturn. This is interpreted as the long time end of a short-time relaxation process in the distribution of relaxation times.…”

Section: Discussionmentioning

confidence: 96%

“…Furthermore, they showed that there was a strong contribution from the -relaxation process to the dielectric loss. 15 More recently, measurements of the shear loss modulus G@(!) for PHMA as a function of temperature at constant frequency have shown theand -relaxation processes along with a third process called the -relaxation.…”

Section: Cðtþ ¼mentioning

confidence: 99%

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Evidence for the γ‐relaxation in the light scattering spectra of poly (n‐hexyl methacrylate) near the glass transition

Savin

Patterson

Stevens

2005

J Polym Sci B Polym Phys

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The full range of relaxation processes present in optically pure poly-(n-hexyl methacrylate) (PHMA) was studied using Rayleigh-Brillouin and photon correlation spectroscopy (PCS). Brillouin shifts, linewidths, and Landau-Placzek ratios (LPR) were measured over the temperature range from À11 to 21 8C. The Brillouin splitting and linewidth were consistent with previous studies of PHMA, but the LPR was much lower, indicating that the scattered light primarily comes from intrinsic density fluctuations. Relaxation functions of the same PHMA sample were measured using PCS over the temperature range 0.5-52.5 8C. The average relaxation times calculated from a Williams-Watts fit follow a VFT temperature dependence, with the stretching parameter decreasing with decreasing temperature. The distribution of relaxation times reveals a merging of the and -relaxations over this temperature range, and the temperature dependent width confirms that there are at least two processes with separate temperature dependences. Furthermore, there appears a process at short times in the correlation function window at low temperatures. This upturn at the fastest relaxation times is attributed to the -relaxation present in higher order methacrylate polymers. The effect of the -relaxation is discussed in terms of the dynamic behavior over 12 decades in time. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1504-1519, 2005

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Dielectric studies of the methacrylate series. III. Poly‐n‐hexyl methacrylate. IV. Poly‐n‐octyl methacrylate

Cited by 19 publications

References 3 publications

Photon correlation spectroscopy of bulk poly(n‐hexyl methacrylate) near the glass transition

Photon correlation spectroscopy of bulk poly(n‐hexyl methacrylate) near the glass transition

Study of the dielectric relaxation of poly(phenylpropyl acrylate) and poly(phenylpropyl methacrylate): effect of slight differences in chemical structure

Evidence for the γ‐relaxation in the light scattering spectra of poly (n‐hexyl methacrylate) near the glass transition

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