Effects of Molecular Weight Reduction on Brittle–Ductile Transition and Elastic Yielding Due to Noninvasive γ Irradiation on Polymer Glasses

2017 ◽  
Vol 50 (6) ◽  
pp. 2447-2455
Author(s):  
Panpan Lin ◽  
Quan Xu ◽  
Shiwang Cheng ◽  
Xiaoxiao Li ◽  
Zhichen Zhao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Reduction ◽  
Polymer Glasses ◽  
Γ Irradiation ◽  
Brittle Ductile Transition ◽  
Elastic Yielding

The effect of sterilizing doses of γ-irradiation on the molecular weight and emulsification properties of gum arabic

1988 ◽  
Vol 2 (5) ◽  
pp. 407-415 ◽  
Author(s):  
S.M. Blake ◽  
D.J. Deeble ◽  
G.O. Phillips ◽  
A. Du Plessey
Keyword(s):  
Molecular Weight ◽  
Gum Arabic ◽  
Γ Irradiation

scholarly journals Increased synthesis of low-molecular-weight nuclear ribonucleic acids of rat liver after γ irradiation and hepatectomy

1975 ◽  
Vol 146 (2) ◽  
pp. 357-360 ◽  
Author(s):  
A Fónagy ◽  
E J Hidvégi
Keyword(s):  
Molecular Weight ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Orotic Acid ◽  
Low Molecular Weight ◽  
Polyacrylamide Gels ◽  
Γ Irradiation ◽  
Ribonucleic Acids

Incorporation of [3H]orotic acid into low-molecular-weight nRNA of rat liver, fractionated on polyacrylamide gels, increased 6-12h after partial hepatectomy and 6h after γ-irridation at 2000 R. The incorporation of orotic acid was particularly increased into the 4.5S, 5S and approx. 10S nRNA fractions. If the irradiation was given after 6h of regeneration and RNA was isolated from the nucleus 12h after hepatectomy then the incorporation of orotic acid into these low-molecular-weight nRNA components was greater than after hepatectomy or irradiation alone.

Effect of Irradiation on the Molecular Weight, Structure and Apparent Viscosity of Xanthan Gum in Aqueous Solution

2011 ◽  
Vol 239-242 ◽  
pp. 2632-2637 ◽  
Author(s):  
Yan Jie Li ◽  
Yi Ming Ha ◽  
Feng Wang ◽  
Yong Fu Li
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Apparent Viscosity ◽  
Irradiation Dose ◽  
Xanthan Gum ◽  
Gel Permeation Chromatography ◽  
Uv Spectra ◽  
X Ray Diffraction ◽  
Γ Irradiation ◽  
Radiation Chemical

Xanthan gum samples were irradiated in aqueous solution at different doses (0-120 kGy) of 60Co γ-rays. The changes of molecular weight and structures of irradiated xanthan gum samples were investigated and characterized by using gel permeation chromatography(GPC), X-ray diffraction (XRD), fourier-transform infrared spectra (FTIR), ultraviolet–visible spectral (UV–vis) analysis and rheometer. Results showed the molecular weight decreased gradually with increasing irradiation dose. The radiation chemical yields G(d) of xanthan gum was 26.55. FTIR spectra and XRD indicated that γ-irradiation introduced no significant changes into the structure and crystal texture, but UV spectra showed a distinct absorption peak at about 265 nm, increasing with irradiation dose, which was attributed to the formation of carbonyl groups or double bond. Apparent viscosity of xanthan gum solution decreased with increasing irradiation dose and remain basically constant with the prolonging of shear time after irradiation.

scholarly journals Influence of the polymer molecular weight on the microstructure of hybrid materials prepared by γ-irradiation

2015 ◽  
Vol 106 ◽  
pp. 126-129 ◽  
Author(s):  
Joana J.H. Lancastre ◽  
António N. Falcão ◽  
Fernanda M.A. Margaça ◽  
Luís M. Ferreira ◽  
Isabel M. Miranda Salvado ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hybrid Materials ◽  
Polymer Molecular Weight ◽  
Γ Irradiation

scholarly journals Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics and Their Molecular Weight Dependence in a Polymer Glass

2021 ◽  
Author(s):  
Stephen Picken ◽  
Georgy Filonenko
Keyword(s):  
Molecular Weight ◽  
Molecular Probes ◽  
Key Factors ◽  
Polymer Glasses ◽  
Polymer Glass ◽  
Irregular Structure ◽  
Glassy Materials ◽  
Environmentally Sensitive ◽  
Induced Defects ◽  
The Impact

Polymer glasses have an irregular structure. Among the causes for such complexity are the chemically distinct chain end-groups that are the most abundant irregularities in any linear polymer. In this work we demonstrate that chain end induced defects allow polymer glasses to create confined environments capable of hosting small emissive molecules. Using environmentally sensitive luminescent complexes we show that the size of these confinements depends on molecular weight and can dramatically affect the photoluminescence of free or covalently bound emissive complexes. We confirm the impact of chain end confinement on the bulk glass transition in poly(methyl acrylate) and show that commonly observed T<sub>g</sub> changes induced by the chain ends should have a structural origin. Finally, we demonstrate that size and placement of luminescent molecular probes in pMA can dramatically affect the probe luminescence and its temperature dependence suggesting that polymer glass is a highly irregular and complex environment marking its difference with conventional small molecule solvents. Considering the ubiquity of luminescent glassy materials, our work lays down a blueprint for designing them with structural considerations in mind, ones where packing density and chain end size are key factors.

Effect of Additive on Hardness and Brittleness in Polycarbonate Films

2007 ◽  
Author(s):  
Suresh Ahuja
Keyword(s):  
Molecular Weight ◽  
Elastic Modulus ◽  
Polymer Surfaces ◽  
Contact Deformation ◽  
Nano Indentation ◽  
Chain Mobility ◽  
Brittle Ductile Transition ◽  
Different Strains ◽  
Number Of Segments ◽  
Weight Number

Hardness and modulus of a polymer composite is known to depend on its structure, molecular weight, number of segments between entanglements and additives (filler). Nano-indentation is used increasingly as a powerful tool to determine hardness and visco-elastic modulus of polymer surfaces linear, cross-linked or composites. Hysitron Nanoindenter was used in our investigation of contact deformation of surfaces of filled polycarbonates supported on aluminum substrate. Bar coatings of polymer films were made from solution and dried all at 110C for half an hour. The results show that filled polycarbonate gives higher hardness than unfilled polycarbonate, which can give significantly different temperature dependence depending on molecular weight of the polycarbonate and structure of the filler. Depending on the type of filler and its concentration, the polycarbonate composite exhibits brittle-ductile transition at different strains. This behavior is analyzed in terms of chain mobility and free volume in the composite.

Effect of γ-Irradiation of Cellulose on the Molecular-Weight Characteristics of Nitro Esters Produced from It

2018 ◽  
Vol 52 (6) ◽  
pp. 504-507
Author(s):  
V. B. Komarov ◽  
A. F. Seliverstov ◽  
Yu. O. Lagunova ◽  
S. V. Gornostaeva ◽  
B. G. Ershov
Keyword(s):  
Molecular Weight ◽  
Γ Irradiation ◽  
Molecular Weight Characteristics ◽  
Nitro Esters
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