Rayleigh‐brillouin spectroscopy of syndiotactic poly(<i>n</i>‐butyl methacrylate) near the glass transition

Patterson, G. D.; Jue, P. K.; Stevens, J. R.

doi:10.1002/polb.1990.090280404

Cited by 15 publications

(13 citation statements)

References 53 publications

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“…11). Lacabanne and coworkers 30 has observed that the T g value of poly(n-BMA) is 338C, whereas Patterson et al 31 measured it as 558C. The T g value reported in this work is in accordance with the literature.…”

Section: Differential Scanning Calorimetrysupporting

confidence: 90%

Radical polymerization of n‐butyl methacrylate initiated by stibonium ylide

Srivastava

2006

J of Applied Polymer Sci

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1,2,3,4-Tetraphenylcyclopentadiene triphenyl stibonium ylide initiated radical polymerization of n-butyl methacrylate (n-BMA) in dioxane at (60 6 0.2)8C for 90 min under nitrogen atmosphere has been carried out. H NMR spectrum shows a peak of two magnetically equivalent protons of methylene group at 2.1 d ppm. The DSC curve shows glass transition temperature (T g ) as 418C. The presence of six hyperfine lines in ESR spectrum indicates that the system follows free radical polymerization and the initiation is brought about by phenyl radical.

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Section: Differential Scanning Calorimetrysupporting

confidence: 90%

Radical polymerization of n‐butyl methacrylate initiated by stibonium ylide

Srivastava

2006

J of Applied Polymer Sci

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“…Polymers near the glass transition temperature have theoretical LPRs around 1.5 to 1.7. 25 This is the value that would be expected if the light scattering comes entirely from density fluctuations. The LPR reported for many Brillouin scattering studies readily exceeds the intrinsic value.…”

Section: Rayleigh-brillouin Spectroscopymentioning

confidence: 84%

“…1 /dT is expected to become smaller. 25 In the present case, all samples were annealed to equilibrium, so there were no glass transition effects present. Meier reports Brillouin splitting data for PHMA that exhibits a broad change in slope between À0.2 and 5.0 8C.…”

Section: Rayleigh-brillouin Spectroscopymentioning

confidence: 95%

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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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“…11). Lacabanne and coworkers30 has observed that the T g value of poly( n ‐BMA) is 33°C, whereas Patterson et al31 measured it as 55°C. The T g value reported in this work is in accordance with the literature.…”

Section: Thermal Analysismentioning

confidence: 99%

Understanding social obstacles to early breast cancer detection is critical to improving breast cancer outcome in low‐ and middle‐resource countries

Anderson

2010

Cancer

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In most low-and middle-resource countries (LMCs), breast cancer incidence rates are increasing more rapidly than in regions where incidence rates already are high. Despite the younger age structure of most developing countries, LMCs already account for 45% of the incident breast cancer cases and cause 54% of the annual breast cancer deaths around the globe. 1 Even assuming (conservatively) that there will be no change in underlying age-specific rates, a nearly 50% increase is anticipated in breast cancer global incidence and mortality between the years 2002 and 2020 caused simply by the aging of current global populations. These rising cancer rates will be disproportionately greater among countries in the developing world, and the rates in LMCs are projected to reach a 55% increased incidence and a 58% increased mortality in <20 years. 1 In reality, these projected statistics probably underestimate future cancer rates, because the few data available from LMCs reveal increasing age-specific breast cancer incidence and mortality rates, especially among recent birth cohorts. This is especially true for urban women in LMCs and is attributable in part to the adoption of Western lifestyles. 2,3 Improvements in breast cancer survival in the industrialized world that have been observed in recent decades can be attributed to early detection by screening combined with timely and effective treatment as guided by the results of extensive and rigorously performed clinical trials. 4 Randomized trials of screening mammography combined with clinical breast examination (CBE) initiated in the 1970s demonstrated that early cancer detection within a given population leads to down-staging of disease and improvement in breast cancer survival. At the same time, randomized trials of systemic therapies for breast cancer proved that endocrine therapy for estrogen receptor (ER)-positive cancers and cytotoxic chemotherapy for ER-negative cancers improve survival and produce durable long-term cure among patients with lymph node negative, lymph node positive, and even locally advanced breast cancers. 5 Breast cancer mortality essentially was unchanged in the United States for 6 decades between 1930 and 1990. By contrast, since 1990, age-adjusted breast cancer mortality has been dropping by nearly 2% each year in the United States, indicating that true progress is being made in the management of this disease. 6 Similar improvements also are being observed in Western European countries that have invoked population-wide early detection and adjuvant treatment programs.Notably, minority women in the United States are more likely to present with advanced stage disease and have higher mortality rates than white women, although white women and black women who present with similar stage disease and receive similar treatment have similar outcomes. These findings suggest that differences in stage at presentation should represent a primary target for research, the goal of which is to determine which interventions best reduce disparities in cancer outcom...

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Rayleigh‐brillouin spectroscopy of syndiotactic poly(n‐butyl methacrylate) near the glass transition

Cited by 15 publications

References 53 publications

Radical polymerization of n‐butyl methacrylate initiated by stibonium ylide

Radical polymerization of n‐butyl methacrylate initiated by stibonium ylide

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

Understanding social obstacles to early breast cancer detection is critical to improving breast cancer outcome in low‐ and middle‐resource countries

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