Estimates of Molecular Weights of Low Molecular Weight Linear Polyethylenes via Differential Scanning Calorimetry

1993 ◽  
Vol 48 (2) ◽  
pp. 215-220 ◽  
Author(s):  
C.M. Feng ◽  
M.S. Delaney
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Low Molecular Weight ◽  
Scanning Calorimetry ◽  
Molecular Weights

Comparison of Electron and Infrared Spectroscopy with Thermal Analysis to Study Molecular Weight Effects in PVC-PMMA Blends

1993 ◽  
Vol 47 (10) ◽  
pp. 1636-1642 ◽  
Author(s):  
Cindy A. Burkhardt ◽  
Joseph A. Gardella
Keyword(s):  
Thermal Analysis ◽  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Infrared Spectroscopy ◽  
Lower Molecular Weight ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Solvent Cast ◽  
Pmma Blends

The effects of homopolymer molecular weight on the miscibility of PVC/PMMA solvent cast blends were studied. Two significantly different molecular weights were chosen for each of the homopolymers, and a series of blends was prepared from the four possible homopolymer-homopolymer combinations. Angle-dependent ESCA results suggest that the surfaces of the blends are enriched with PMMA. The extent of this enrichment is dependent on molecular weight, with the most enrichment seen in blends containing the lower-molecular-weight PMMA homopolymer. Differential scanning calorimetry (DSC) results are also presented.

scholarly journals Properties and structure of high temperature resistant cyanate ester/polyethersulfone blends using solvent-free toughening approach

2020 ◽  
Author(s):  
Lyaysan Amirova ◽  
Fabian Schadt ◽  
Markus Grob ◽  
Christian Brauner ◽  
Thomas Ricard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Network Formation ◽  
Mechanical Analysis ◽  
Solvent Free ◽  
Cyanate Ester ◽  
Low Molecular Weight ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
The Difference

AbstractA high temperature resistant novolac cyanate ester was blended with polyethersulfone (PES) with different molecular weights using the solvent-free approach. The phase separation, curing behavior and thermal properties were studied using hot stage microscopy, differential scanning calorimetry and dynamic mechanical analysis. Results showed the difference in the morphology for blends with different molecular weight PES explained by possible network formation. The influence of PES content on the glass transition temperature and mechanical properties was investigated. The most significant toughening effect (increase of 132% in fracture toughness) was achieved on a functionalized low molecular weight PES (20 parts per hundred of resin, phr). Rheology investigation allowed to estimate the optimal content of PES (15 phr) for further prepreg manufacturing.

Effect of Molecular Weight on Glass Transition by Differential Scanning Calorimetry

1974 ◽  
Vol 52 (18) ◽  
pp. 3170-3175 ◽  
Author(s):  
Louis-Philippe Blanchard ◽  
Jean Hesse ◽  
Shadi Lal Malhotra
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Glass Transition ◽  
Heating Rate ◽  
Low Molecular Weight ◽  
Glass Transitions ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Polystyrene Sample

The influence of molecular weight (900 to 1.8 × 106) on the glass transition temperature of low polydispersity polystyrene (anionically prepared) has been studied by differential scanning calorimetry at heating rates of 5 to 80 °C min−1. Over the range of molecular_weight studied, and at an extrapolated heating rate of 1 °C min−1,[Formula: see text] A thermally prepared polystyrene sample ([Formula: see text]and Pd = 3.2) showed a Tge value of 93 °C, some 10° below the value predicted by the above equation. Low molecular weight species in the highly polydisperse sample are believed to be responsible for the discrepancy. The changes in heat capacity brought about by the glass transitions are accompanied in all cases on heating by an endothermic peak and this regardless of the heating rate (even extrapolated to 1 °C min−1) or the molecular weight of the sample, suggesting that the glass transition phenomenon encountered with polystyrene is a process involving a positive heat effect.

Glass Transition Behavior of Polyisoprene: The Influence of Molecular Weight, Terminal Hydroxy Groups, Microstructure, and Chain Branching

1982 ◽  
Vol 55 (1) ◽  
pp. 245-252 ◽  
Author(s):  
C. Kow ◽  
M. Morton ◽  
L. J. Fetters ◽  
N. Hadjichristidis
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Low Molecular Weight ◽  
Hydroxyl Groups ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
Chain Branching ◽  
Glass Transition Temperatures ◽  
Hydroxy Groups

Abstract The glass transition temperatures for a series of high-1,4 linear and star-branched polyisoprenes have been measured by differential scanning calorimetry. The Fox-Flory relation for the linear polyisoprenes was found to be Tg=Tg∞−1.76×104Mn−1. The influence of hydroxyl groups on Tg was also examined for low molecular weight (<2.2×104) polyisoprenes.

scholarly journals THE MICELLIZATION OF PLURONICS (PEO-PPO-PEO TRIBLOCK COPOLYMERS)

2009 ◽  
Vol 12 (3) ◽  
pp. 85-94
Author(s):  
Hung Quoc Nguyen ◽  
Søren Hvidt ◽  
Walther Batsberg ◽  
Cuong Ngoc Hoang
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Triblock Copolymers ◽  
Low Molecular Weight ◽  
Hexane Extraction ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Effects Of Temperature ◽  
Molecular Weight Fractions ◽  
Dsc Thermograms

The micellization of several Pluronics (PEO-PPO-PEO triblock copolymers) was investigated by Differential Scanning Calorimetry (DSC). These copolymers were also characterized and purified by liquid chromatography. The PEO/PPO compositions of Pluronics were determined by 'H-NMR. The thermograms from DSC showed a pre micellization shoulder for L81 and L121 solutions. The effects of temperature, PO/EO ratios and impurities on the micellization of copolymers were investigated. The origin of the shoulders in DSC thermograms was shown to be due to the most hydrophobic components in the copolymers, which could be removed by hexane extraction. Low molecular weight fractions of the copolymers were separated by interaction chromatography. The low molecular weight fractions did not contribute to the micellization of the copolymers.

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