Applicability of the WLF equation to polyurethane polyols and film properties of their resins

Haseebuddin, Syed; Raju, K. Mohana; Yaseen, Mohammed

doi:10.1016/s0300-9440(96)00650-9

Cited by 13 publications

(6 citation statements)

References 6 publications

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“…Copolymers 2 − 6 exhibit a single T g with the value gradually shifted from 93 to 115 °C. The T g values fit well with the linear WLF equation of 1/ T g = W OPV (1/ ) + W OXD (1/ ) with the correlation coefficient of R = 0.98 (Figure ), in which W OPV and W OXD are the weight fractions of the OPV and the OXD units in the polymer and and are the T g 's of 1 and 7 , respectively (Figure ) . This result is consistent with the assumption that the copolymers are random copolymers rather than block copolymers.…”

Section: Resultssupporting

confidence: 82%

High-Performance Hole-Transport Polyurethanes for Light-Emitting Diodes Applications

et al. 2006

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A novel family of hole-transport polyurethanes (PUs) has been developed. The PUs were prepared from the condensation polymerization of isophorone diisocyanate (IPDI) with (E,E)-1,4-bis(2-hydroxystyryl)benzene, an oligo p-phenylene-(E)-vinylene (OPV) unit, and various amounts of 2,5-bis(4hydroxyphenyl)-1,3,4-oxadiazole (OXD), as well as with 4-tert-butyl phenol as the terminal group. The PUs demonstrates superior properties that were concluded on the basis of the improved current injection in the corresponding hole-only device. The OLED device with the OPV-PU interfacial layer inserted in ITO/PEDOT:PSS(20 nm)/PU(30 nm)/R-NPB(10 nm)/Bebq 2 (20 nm)/Ca(10 nm)/Ag(100 nm) has a dramatic voltage reduction of 2.5 V under the current density of 100 mA/cm 2 . When compared to the control device, the current efficiency was improved 2.37 times. The maximum brightness increased to 14900 cd/m 2 in comparison to that of 5780 cd/m 2 for the control device. The performance of the OLED devices was fine-tuned by adjusting the combination of the OPV and OXD units to reach electron-hole balanced conditions. The maximum current efficiency increased to 4.12 cd/A at 5.5 V when the PU layer of OPV: OXD ) 67:33 was used.

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Section: Resultssupporting

confidence: 82%

High-Performance Hole-Transport Polyurethanes for Light-Emitting Diodes Applications

et al. 2006

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“…On the contrary, a lot of discussion is based on the assumption of a constant viscosity at T g . For low‐MW polymers, the viscosity at T g was assumed to be 10 12 – 10 13 P in several literature studies 33, 42, 62–64. For biomaterials also it was assumed to be around 10 11 – 10 12 P 65–67…”

Section: Resultsmentioning

confidence: 99%

Deoxycitidine kinase is associated with prolonged survival after adjuvant gemcitabine for resected pancreatic adenocarcinoma

Maréchal

Mackey

Lai

et al. 2010

Cancer

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BACKGROUND: Gemcitabine (2 0 ,2 0 -difluorodeoxycytidine) administration after resection of pancreatic cancer improves both disease-free survival (DFS) and overall survival (OS). Deoxycytidine kinase (dCK) mediates the ratelimiting catabolic step in the activation of gemcitabine. The authors of this report studied patient outcomes according to the expression of dCK after a postoperative gemcitabine-based chemoradiation regimen. METHODS: Fortyfive patients with resected pancreatic adenocarcinoma received adjuvant gemcitabine based-therapy in the context of multicenter phase 2 studies. Their tumors were evaluated retrospectively for dCK protein expression by immunohistochemistry. A composite score based on the percentage of dCK-positive cancer cells and the intensity of staining was generated, and the results were dichotomized at the median values. RESULTS: The median follow-up was 19.95 months (95% confident interval [CI], 3.3-107.4 months). The lymph node (LN) ratio and dCK protein expression were significant predictors of DFS and OS in univariate analysis. On multivariate analysis, dCK protein expression was the only independent prognostic variable (DFS: hazard ratio [HR], 3.48; 95% CI, 1.66-7.31; P ¼ .001; OS: HR, 3.2; 95% CI,1.44-7.13; P ¼ .004). CONCLUSIONS: dCK protein expression was identified as an independent and strong prognostic factor in patients with resected pancreatic adenocarcinoma who received adjuvant gemcitabine therapy. The authors concluded that it deserves prospective evaluation as a predictive biomarker for patient selection. Cancer 2010;116:5200-6.

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“…Secondary reactions in solution free-radical acrylic polymerization become important at high temperatures and strongly influence the nature of the polymer formed . A fundamental understanding of the influence of the various secondary reaction mechanisms is valuable for both designing and optimizing the high-temperature polymerization processes and their products. − …”

Section: Introductionmentioning

confidence: 99%

“…1 A fundamental understanding of the influence of the various secondary reaction mechanisms is valuable for both designing and optimizing the high-temperature polymerization processes and their products. [2][3][4][5] High-temperature polymerizations of styrene and ethylene are well studied. Styrene is known to thermally polymerize 6,7 and ethylene to form branched polymer chains.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Homopolymerization of Ethyl Acrylate and n-Butyl Acrylate: Polymer Characterization

Quan¹,

Soroush²,

Grady³

et al. 2005

Macromolecules

113

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This paper presents a thorough molecular characterization of ethyl acrylate (EA) and n-butyl acrylate (nBA) homopolymers made at high temperature (140−180 °C) to high conversions (50−90%) in xylene isomers without the use of added thermal initiator. Electrospray ionization/Fourier transform mass spectrometry (ESI/FTMS) analysis shows four dominant chain types formed during high-temperature polymerization. Chains initiated by β-scission radicals and by xylol radicals that grow and eventually terminate to form terminally saturated and unsaturated chains. These chain structures suggest the underlying secondary mechanisms in high-temperature acrylate polymerization include β-scission (disproportionation) of the carbon-centered tertiary radical that is most likely formed via intramolecular chain transfer. Additionally, chain transfer to solvent, xylene in this case, also plays an important mechanistic role. Results from 1D NMR using 13C, 1H, and distortionless enhancement polarization transfer (DEPT) corroborate the ESI/FTMS results and additionally predict (i) 2 branch points per chain on average for EA homopolymer with a number-average molecular weight of 4000 and (ii) 1.25 branch points per chain on average for nBA homopolymer with a number-average molecular weight of 3300. The presence of branch points indicates propagation of the midchain tertiary radical does occur to significant extent under the conditions of the experiments. Neither the ESI/FTMS nor NMR results suggest a mechanistic route by which the acrylates initiate polymerization without added thermal initiator.

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Applicability of the WLF equation to polyurethane polyols and film properties of their resins

Cited by 13 publications

References 6 publications

High-Performance Hole-Transport Polyurethanes for Light-Emitting Diodes Applications

High-Performance Hole-Transport Polyurethanes for Light-Emitting Diodes Applications

Deoxycitidine kinase is associated with prolonged survival after adjuvant gemcitabine for resected pancreatic adenocarcinoma

High-Temperature Homopolymerization of Ethyl Acrylate and n-Butyl Acrylate: Polymer Characterization

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