γ-Irradiation of N-vinylpyrrolidin-2-one and its homopolymer

1981 ◽  
Vol 34 (7) ◽  
pp. 1413 ◽  
Author(s):  
JE Davis ◽  
E Senogles
Keyword(s):  
Molecular Weight ◽  
Hydrogen Bonding ◽  
Main Chain ◽  
Theoretical Data ◽  
Radical Mechanism ◽  
Promoting Effect ◽  
Γ Irradiation ◽  
Radiation Chemical ◽  
Γ Radiation ◽  
Molecular Weights

The effect of γ-radiation on N-vinylpyrrolidin-2-one and its homopolymer, poly(N-vinylpyrrolidin-2-one), has been investigated. With N-vinylpyrrolidin-2-one, polymerization occurs by a radical mechanism and the presence of water has been shown to have a promoting effect on the reaction, giving both increased polymerization rates and molecular weights. This has been primarily attributed to an enhancement of N- vinylpyrrolidin-2-one reactivity through hydrogen bonding. In contrast, irradiation of N-vinylpyrrolidin-2-one in the presence of organic solvents leads to lower polymerization rates and lower molecular weights than with the undiluted monomer. ��� Poly(N-vinylpyrrolidin-2-one) primarily crosslinks on being irradiated. Gel fractions have been determined as a function of radiation dose and the results shown to be consistent with the theoretical data derived by Inokuti for a polymer with an initial molecular weight distribution of the Schulz-Zimm type. This leads to values for the radiation chemical yields of crosslinks and main chain scissions, G(X) and G(S), of 0.13�0.03 and 0.02�0.01, respectively, at 0°C.

Radiation Chemical Conversions in Fluorine Containing Elastomers under Different γ-Irradiation Conditions

1974 ◽  
Vol 47 (2) ◽  
pp. 282-284 ◽  
Author(s):  
A. B. Kryukova ◽  
A. S. Kuz'minskii ◽  
N. S. Gilinskaya ◽  
F. A. Galil-Ogly ◽  
G. A. Sankina
Keyword(s):  
Stressed State ◽  
Vinyl Ether ◽  
High Temperatures ◽  
Vinylidene Fluoride ◽  
Chemical Crosslinking ◽  
Γ Irradiation ◽  
Radiation Chemical ◽  
Γ Radiation ◽  
Copolymer 1

Abstract Rates of radiation chemical crosslinking and scission of fluorine containing elastomers based on copolymers of vinylidene fluoride with trifluorochloroethylene (Copolymer 1), with hexafluoropropylene (Copolymer 2), and with a perfluoroalkyl vinyl ether (Copolymer 3) and also the behavior of their radiation vulcanizates in the stressed state at high temperatures are determined both by the type of polymer and by the irradiation conditions. Crosslinking rates of Copolymers 2 and 3 are higher than those of Copolymer 1; oxygen of the air inhibits crosslinking by γ-radiation; by irradiation in the presence of oxygen of the air, the sol fraction is 8–10 times higher than in its absence, Copolymer 3 vulcanizates obtained by irradiation in the absence of air appear to be optimal.

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.

The degradation of solid polymethylmethacrylate by ionizing radiation

1954 ◽  
Vol 223 (1154) ◽  
pp. 392-404 ◽  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
High Energy ◽  
Side Chain ◽  
Radiation Doses ◽  
Cage Effect ◽  
Γ Radiation ◽  
High Energy Radiation ◽  
Direct Dissociation ◽  
Solid Form

When polymethylmethacrylate in the solid form is irradiated in the atomic pile, or with γ-radiation, two reactions predominate: breakdown of the main chain, and decomposition of the side chain with evolution of gases. The former was followed by changes in viscosity, the molecular weight of the irradiated polymer being inversely proportional to the radiation dose (plus a small quantity of R 0 which depends on the initial molecular weight). The degradation is thought to proceed by random rupture of main-chain C— C bonds by rearrangement of the excited polymer, and 61 eV are absorbed per fractured bond. For each main-chain rupture approximately one ester side chain is also decomposed. The cage effect is thought to prevent direct dissociation, and reaction occurs by rearrangement of the molecule to give relatively stable entities. Added substances reduce the amount of degradation, possibly by transfer of energy from the excited polymer molecule. This is only possible if the excited molecules have an appreciable life before decomposition. Viscosity measurements on irradiated polymethylmethacrylate in the solid form offer a possible means of measuring high-energy radiation doses in the range of about 1 million röntgens and upwards.

Solution Properties of Polybutadiene and trans-Polyisoprene Fractions

1963 ◽  
Vol 36 (2) ◽  
pp. 488-501
Author(s):  
W. Cooper ◽  
D. E. Eaves ◽  
G. Vaughan
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Benzene Solution ◽  
Second Virial Coefficient ◽  
Virial Coefficients ◽  
Γ Radiation ◽  
Branched Polymer ◽  
Butyl Lithium ◽  
Second Virial Coefficients ◽  
Molecular Weights

Abstract Linear polybutadienes, prepared with butyl lithium as catalyst, and polybutadienes branched by exposure to γ-radiation have been fractionated and the fractions examined by osmometry and light scattering. Turbidimetric second virial coefficients (A2τ) of mixed polymer fractions are virtually the same as those of the higher molecular weight components of the mixtures for most compositions. This is true both for mixtures of linear with linear and linear with branched polymer. The higher the molecular weight of the fraction, the greater the effect; the addition of 1 per cent microgel to a linear polymer reduced A2τ by a factor of three. The presence of microgel or high molecular weight branched polymer has been shown to be responsible for the very high molecular weights previously reported for polybutadienes from light scattering measurements. It is conveniently removed by shaking the solutions with calcium sulfate. Second virial coefficients obtained either by light scattering or osmometry are, within the limits of experimental error, uninfluenced by branching in the polymer. In general those factors which lead to increased branching also result in increased polydispersity, and it is the latter which results in the decrease in A2τ. The fall of the osmotic second virial coefficient (A2τ) with molecular weight is much smaller than would be calculated theoretically, and the fall in A2τ is greater than would be expected, notwithstanding the fact that for some of the fractions Mw/Mn<1.1. This indicates that A2τ is sensitive to the low molecular weight species present in the fractions, whereas the reverse must apply to A2τ. Natural or synthetic trans-polyisoprene showed analogous behavior to polybutadiene, although, owing to experimental difficulties, sharp branched fractions could not be obtained. The following viscosity-molecular weight relationships were obtained in benzene solution: [η]=1.45×10−4M0.76 for butyl lithium-catalyzed polybutadienes, and [η]=4.37×10−4M0.65 for natural and synthetic trans-polyisoprenes.

scholarly journals Differences in expression density and molecular weight of CR1-Like in erythrocytes of landrace swine

2018 ◽  
Author(s):  
Jingjing Zhang ◽  
Wei Yin ◽  
Chun Wang ◽  
Ruipu Jia ◽  
Kuohai Fan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Theoretical Data ◽  
Flow Cytometry Analysis ◽  
Immunological Mechanism ◽  
Future Studies ◽  
Molecular Weights ◽  
Immune Adherence ◽  
Sds Page ◽  
Complement Receptor 1 ◽  
Porcine Erythrocyte

Background. Porcine erythrocytes express complement receptor 1-like (CR1-like), which is involved in immune adherence. Methods. In this study, porcine erythrocyte samples were collected from fifty-five individual Landrace swine to characterize differences in porcine CR1-like. Flow cytometry analysis was performed to examine the porcine differences in CR1-like expression density and immunoprecipitation, SDS-PAGE and Western blot were performed to detect variations in porcine CR1-like molecular weights. Results. Different mean fluorescence intensities (MFI) of porcine erythrocytes were identified in three groups as 33.016±2.889 (40.0%), 59.974±9.299 (45.5%) and 131.241±8.375 (14.5%). Under reduced condition, three porcine CR1-like molecular weight variants were identified as 85.280±0.935 kDa (9.09%), 123.939±2.752 kDa (14.55%) and 136.696±2.028 kDa (76.36%). Discussion. CR1-like was dispersed on the surface of porcine erythrocytes and promoted immune adherence. There have been no reports on whether differences in the expression levels and/or molecular weights of CR1-like in erythrocytes represent diversity in different individuals, and if so, whether this diversity influences the immune adherence of erythrocytes and/or whether the diversity is associated with CR1-like polymorphisms. At present, five candidate genes that are related to the differences above were found. Research examining erythrocyte immune adherence and CR1-like genes is under way. These results will provide theoretical data for future studies of the immunological mechanism of CR1-like in porcine erythrocytes.

Molecular-weight dependence of the formation of highly ordered lamellar structures of poly(N-dodecyl acrylamide) by humid annealing

2019 ◽  
Vol 10 (7) ◽  
pp. 835-842 ◽  
Author(s):  
Kazuki Ebata ◽  
Yuki Hashimoto ◽  
Kohei Ebara ◽  
Mayu Tsukamoto ◽  
Shunsuke Yamamoto ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
Side Chains ◽  
Molecular Weights ◽  
Lamellar Structures ◽  
Molecular Weight Dependence ◽  
Alkyl Side Chains

Highly oriented lamellar films of poly(N-dodecylacrylamide) with high molecular weights were formed by nanosegregation between alkyl side chains and a water-adsorbed main chain.

Molecular-weight changes in the degradation of long-chain polymers

1954 ◽  
Vol 224 (1156) ◽  
pp. 120-128 ◽  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
High Energy ◽  
Initial Distribution ◽  
Weight Changes ◽  
Chain Polymer ◽  
High Energy Radiation ◽  
Molecular Weights ◽  
Random Fracture ◽  
Long Chain

The changes in molecular weight of a long-chain polymer (initially of arbitrary molecular-weight distribution) are studied when the main chain is subjected to random fracture, such as occurs when certain polymers are exposed to high-energy radiation. For several distributions studied, all trace of the initial distribution curve is lost after an average of some 3 to 8 main-chain fractures per molecule. For lower degrees of degradation the shape of the curve of weight average against degradation can provide information as to the initial weight average, z average, z + 1 average molecular weights. The initial number-average can be obtained by a method of extrapolation.

scholarly journals Differences in expression density and molecular weight of CR1-Like in erythrocytes of landrace swine

2018 ◽  
Author(s):  
Jingjing Zhang ◽  
Wei Yin ◽  
Chun Wang ◽  
Ruipu Jia ◽  
Kuohai Fan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Theoretical Data ◽  
Flow Cytometry Analysis ◽  
Immunological Mechanism ◽  
Future Studies ◽  
Molecular Weights ◽  
Immune Adherence ◽  
Sds Page ◽  
Complement Receptor 1 ◽  
Porcine Erythrocyte

Background. Porcine erythrocytes express complement receptor 1-like (CR1-like), which is involved in immune adherence. Methods. In this study, porcine erythrocyte samples were collected from fifty-five individual Landrace swine to characterize differences in porcine CR1-like. Flow cytometry analysis was performed to examine the porcine differences in CR1-like expression density and immunoprecipitation, SDS-PAGE and Western blot were performed to detect variations in porcine CR1-like molecular weights. Results. Different mean fluorescence intensities (MFI) of porcine erythrocytes were identified in three groups as 33.016±2.889 (40.0%), 59.974±9.299 (45.5%) and 131.241±8.375 (14.5%). Under reduced condition, three porcine CR1-like molecular weight variants were identified as 85.280±0.935 kDa (9.09%), 123.939±2.752 kDa (14.55%) and 136.696±2.028 kDa (76.36%). Discussion. CR1-like was dispersed on the surface of porcine erythrocytes and promoted immune adherence. There have been no reports on whether differences in the expression levels and/or molecular weights of CR1-like in erythrocytes represent diversity in different individuals, and if so, whether this diversity influences the immune adherence of erythrocytes and/or whether the diversity is associated with CR1-like polymorphisms. At present, five candidate genes that are related to the differences above were found. Research examining erythrocyte immune adherence and CR1-like genes is under way. These results will provide theoretical data for future studies of the immunological mechanism of CR1-like in porcine erythrocytes.

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