Low-Frequency Vibrational Motions of Polystyrene in Carbon Tetrachloride: Comparison with Model Monomer and Dependence on Concentration and Molecular Weight

2020 ◽  
Vol 124 (10) ◽  
pp. 2006-2016 ◽  
Author(s):  
Hideaki Shirota ◽  
Katsuhiko Moriyama
Keyword(s):  
Molecular Weight ◽  
Carbon Tetrachloride ◽  
Low Frequency

Organomercury compounds. XXIII. Organomercuric Quinolin-8-olates

1978 ◽  
Vol 31 (3) ◽  
pp. 527 ◽  
Author(s):  
RJ Bertino ◽  
GB Deacon ◽  
JM Miller
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Solid State ◽  
Carbon Tetrachloride ◽  
Crystal Structures ◽  
Supporting Evidence ◽  
Visible Spectroscopy ◽  
Organomercury Compounds ◽  
Weight Data

The complexes RHg(ox) (R = C6F5, p-HC6F4, or p-MeOC6F4; ox = quinolin-8- olate) have been prepared by reaction of thallous quinofin-8-olate with the appropriate organomercuric chlorides whilst PhHg(ox or meox), MeHg(ox),H2O, and MeHg(meox) (meox = 2-methylquinolin-8-olate) have been obtained from phenyl- or methyl-mercuric hydroxide and quinolin-8-ol or 2-methyl-quinolin-8-ol. Although MeHg(ox),H2O was readily dehydrated, the water could not be displaced by ligands (e.g. Ph3PO, Me2SO). Chelation of the quinolin-8-olate ligands (rather than unidentate O- bonding) was established for all complexes by ultraviolet/visible spectroscopy. Molecular weight data indicated that all complexes except MeHg(ox) and MeHg(ox),H2O are partly associated in benzene, chloroform and/or carbon tetrachloride [K(2 monomer ↔ dimer) in the range 1-40 mol-1 dm3]; this suggests an associated structure in the solid state. Some supporting evidence for associated structures was obtained by mass spectrometry. The structural conclusions are discussed in the light of crystal structures of PhHg(ox) and PhHg(meox) carried out in a concurrent investigation.

Donor-acceptor complexes formed by perfluoro-organo bromides and iodides with nitrogenous and other bases. III. Qualitative examination of condensed phase spectra of CF3I and CF3Br and of their complexes with trimethylamine and other bases

1974 ◽  
Vol 27 (5) ◽  
pp. 973 ◽  
Author(s):  
NF Cheetham ◽  
IJ McNaught ◽  
ADE Pullin
Keyword(s):  
Carbon Tetrachloride ◽  
Room Temperature ◽  
Low Frequency ◽  
Vapour Phase ◽  
Liquid Solution ◽  
Liquid Mixtures ◽  
Electron Donors ◽  
Solid Films ◽  
Donor Acceptor ◽  
Phase Spectra

This paper reports the spectra of (i) CF3I, CF3Br and N(CH3)3 as solutions in carbon tetrachloride at room temperature, as liquids at lowered temperatures and as solid films at 80 K and (ii) equimolar solutions of CF3I and N(CH3)3 in carbon tetrachloride at room temperature, equimolar liquid mixtures of CF3I and N(CH3)3 at both room and lowered temperatures and annealed solid films at 80 K of CF3I-N(CH3)3 and CF3Br-N(CH3)3. The spectra clearly show the existence of complexes to which, on the bases of evidence reported in Part I, we assign the structures CF3I.N(CH3), and CF3Br.N(CH3),. Differences between the spectra of the complexes and the spectra of the free components for the same phase include (a) the appearance in the spectrum of the complex of a low frequency band which we attribute to the N-I or N-Br stretching mode, (b) a strong band at a lower frequency than the carbon-halogen stretching mode in CF3I or CF3Br which we assign to the modified carbon-halogen stretching mode in the complex, much enhanced in intensity, (c) an increased frequency of the symmetric carbon fluorine stretching mode and a decreased frequency of the degener- ate carbon-fluorine stretching mode in the complex compared with the free components, (d) increase in intensity and frequency of v7 (CNC symmetric bend) of trimethylamine, (e) doubling of several C-H stretching frequencies. The dependence on phase of the magnitudes of the differences in frequencies of corresponding modes in the complex and free components are solid (80 K) > liquid ≈ solution in CCI4 > vapour phase. Some details of complexes of CF3I and CF3Br with some other electron donors are reported briefly.

Influence of Preparation Method and Molecular parameters on the Rheology of Model PEO/ Laponite Nanocomposites

2011 ◽  
Vol 1312 ◽  
Author(s):  
Jesmy Jose ◽  
Abakar Adam Omar ◽  
Guillaume Brotons ◽  
Jean-François Tassin
Keyword(s):  
Molecular Weight ◽  
Preparation Method ◽  
Low Frequency ◽  
Elastic Solid ◽  
Polymer Chains ◽  
Correlation Peak ◽  
Preparation Methods ◽  
Molecular Weights ◽  
Twin Screw ◽  
High Concentrations

ABSTRACTModel polymer nanocomposites based on geometrically well defined and protected Laponite particles dispersed in Poly(ethylene oxide) were investigated in order to improve the understanding of the filler dispersion effects on rheology by varying two experimental factors, namely preparation method and PEO matrix molecular weight. Preparation methods are divided into a solution dispersion and a melt dispersion by twin screw extrusion. The linear viscoelastic properties of the samples prepared by solution method revealed an elastic solid like behaviour at Laponite weight fractions as low as 0.1%, dramatically lower than the percolation threshold so far reported for such kind of systems. The sample preparation by melt dispersion, although leading to dispersed particles, does not achieve the same levels of modulus as compared to solution prepared mixtures. We propose a qualitative interpretation of this phenomenon, based on the mixture between a liquid and a dispersed phase of rather solid character. Further experiments using small angle X-ray scattering techniques (SAXS) show that the modulus level is not necessarily related to the height of the correlation peak characteristic of the Laponite stacks. However, for samples prepared with varying PEO matrix molecular weight the fraction of Laponite stacks decreases with increasing PEO molecular weight. The rheology master curve analyses show that confinements of polymer chains arising from high concentrations of particles and high molecular weight matrix chains do not impact the level of the low frequency modulus. However, a slower polymer dynamics, as observed for higher molecular weights, leads to an increase of the modulus at low particle loadings.

scholarly journals Effect of Low-Frequency Ultrasonic-Assisted Enzymolysis on the Physicochemical and Antioxidant Properties of Corn Protein Hydrolysates

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Qiufang Liang ◽  
Xiaofeng Ren ◽  
Haile Ma ◽  
Suyun Li ◽  
Kangkang Xu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Orthogonal Design ◽  
Protein A ◽  
Antioxidant Properties ◽  
Low Frequency ◽  
Antioxidant Peptides ◽  
Corn Protein ◽  
Ultrasonic Assisted ◽  
Pretreatment Conditions ◽  
Ultrasound Pretreatment

The aim of this study was to investigate the effect of low-frequency ultrasound on the enzymolysis of corn protein. A L9(34) orthogonal design was used to optimize ultrasound pretreatment conditions. Degree hydrolysis (DH), conversion rate of protein (CR), and DPPH IC50were selected as analytical indicators. Under the optimal ultrasound conditions (5 W/L power, 2 s/2 s on/off time, 50°C temperature, and 25 min time), the DH, CR, and radical (DPPH∙,OH∙) scavenging capacities were significantly increased. Molecular weight distribution and amino acid profile analysis showed that ultrasound pretreatment enhanced the formation of short-chain peptides with molecular weight of 200–3000 Da, especially the peptides containing hydrophobic amino acids. Moreover, 40 potential antioxidant peptides were purified by C18 semipreparative column and identified by UPLC-ESI-MS. The results suggest that the optimal ultrasonic-assisted enzymolysis technology could be useful for preparation of antioxidant peptides from corn.

Dynamic Mechanical Properties of Cross-Linked Rubbers. II. Effects of Crosslink Spacing and Initial Molecular Weight in Polybutadiene

1966 ◽  
Vol 39 (4) ◽  
pp. 905-914
Author(s):  
Etsuji Maekawa ◽  
Ralph G. Mancke ◽  
John D. Ferry
Keyword(s):  
Molecular Weight ◽  
Crosslink Density ◽  
Low Frequency ◽  
Dynamic Mechanical Properties ◽  
Cross Linking ◽  
Loss Mechanism ◽  
Low Frequencies ◽  
Molecular Weights ◽  
Monomeric Friction Coefficient ◽  
Lower Frequencies

Abstract The complex shear compliances of eight samples of polybutadiene crosslinked by cumyl peroxide and four samples crosslinked by sulfur have been measured over a frequency range from 0.2 to 2 cps at temperatures from − 6 to 45° C by a torsion pendulum. On four of the samples, measurements were extended by the Fitzgerald transducer from 45 to 600 cps at temperatures from − 71 to 55°. The vulcanizates had been prepared from polymers of two different molecular weights (180,000 and 510,000) with sharp molecular weight distribution; the physical crosslink density ranged from 0.57 to 2.68×10−4 mole/cm3, and the chemical crosslink density calculated following Kraus ranged from 0.22 to 1.49×10−4 mole/cm3. The mechanical data were all reduced to T0=298° K by shift factors calculated from the equation log aT=−3.64(T−T0)/(186.5+T−T0). In the transition zone of frequencies, the viscoelastic functions of the cumyl peroxide vulcanizates were closely similar, except for a shift toward lower frequencies with increasing crosslinking, corresponding to a small but unexpected increase in the monomeric friction coefficient. Cross-linking by sulfur caused a somewhat larger shift toward lower frequencies at a comparable crosslink density. In the rubbery zone, the sample with least cross-linking exhibited a substantial secondary loss mechanism at very low frequencies. The low-frequency losses are evident in all the samples, but their magnitude falls rapidly with increasing crosslink density as previously found for natural rubber. It also falls somewhat with increasing initial molecular weight, indicating a contribution from network strands with loose ends. The possible relation of the low-frequency losses to trapped entanglements is discussed.

Effect of Viscosity Stabilizer on the Properties and Structure of Raw Constant Viscosity Rubber

2012 ◽  
Vol 557-559 ◽  
pp. 947-951
Author(s):  
Yong Zhou Wang ◽  
Ping Yue Wang ◽  
Bei Long Zhang ◽  
Hong Hai Huang ◽  
Li Ding ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Low Frequency ◽  
Hydroxylamine Hydrochloride ◽  
Dynamic Mechanical Properties ◽  
Linear Viscoelastic ◽  
Strain Sweep ◽  
Constant Viscosity

The properties of raw constant viscosity natural rubber were measured using a rubber processing analyzer. The results show that the rubber processing analyzer can characterize well the effect of viscosity stabilizer on the dynamic mechanical properties of raw constant viscosity rubber by applied strain sweep or frequency sweep. In linear viscoelastic region, the increment of the dynamic torque S’ of the constant viscosity natural rubber prepared with hydroxylamine hydrochloride decreases with the increase in the level of hydroxylamine hydrochloride . In the range of low frequency, the increment of the dynamic modulus G’ of constant viscosity natural rubber prepared with hydroxylamine hydrochloride is obvious lower than those of natural rubber and constant viscosity natural rubber prepared with aniline. G’ of the constant viscosity natural rubber prepared with aniline is just only a little higher than that of natural rubber. Hydroxylamine hydrochloride and aniline can decrease the molecular weight of rubber, and change the molecular weight distribution. The dynamical properties of constant viscosity natural rubber are dependent on the molecular weight and the molecular weight distribution.

Low molecular weight heparin prevents hepatic fibrogenesis caused by carbon tetrachloride in the rat

2007 ◽  
Vol 46 (2) ◽  
pp. 286-294 ◽  
Author(s):  
Wataru Abe ◽  
Kenichi Ikejima ◽  
Tie Lang ◽  
Kyoko Okumura ◽  
Nobuyuki Enomoto ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Carbon Tetrachloride ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Hepatic Fibrogenesis

scholarly journals The value of low-molecular-weight DNA of blood plasma in the diagnostic of the patological processes of different genesis

2013 ◽  
Vol 59 (3) ◽  
pp. 358-373 ◽  
Author(s):  
I.N. Vasilyeva ◽  
V.N. Zinkin
Keyword(s):  
Molecular Weight ◽  
Blood Plasma ◽  
Low Frequency ◽  
The Body ◽  
Chronic Obstructive ◽  
Low Molecular Weight ◽  
Frequency Noise ◽  
Obstructive Pulmonary Disease ◽  
Blood Concentrations ◽  
In Blood Plasma

The low-molecular-weight DNA appears in blood plasma of irradiated rats, and its content correlates directly with the irradiation dose. Cloning has shown, that enrichment of low-molecular-weight DNA with G+C content and features of its nucleotide sequences point to its ability to form rather stable nucleosomes. DNA obtained after irradiation of rats with principally different doses 8 and 100 Gy differed not only quantitatively, but also by content of the dinucleotides CpG and CpT; this suggests their origin from different sites of genome. For the first time it has been shown that exposure to low-frequency noise results in an increase of the contents of blood plasma low-molecular-weight DNA. In stroke patients blood concentrations of this DNA increased 3 days after the beginning of the acute period, and dynamics of its excretion differs in ischemic and hemorrhagic forms; in the case of ischemia low-molecular-weight DNA appears in cerebrospinal fluid. The chronic obstructive pulmonary disease in the state of remission is characterized by the decline of the level of low-molecular-weight DNA in the blood plasma unlike in the case of the chronic nonobstructive bronchitis. The clear dependence between formation and special features of the low-molecular-weight DNA fraction in blood plasma makes it possible to consider the low-molecular fraction as an universal index of apoptosis, which allows to distinguish basically different conditions of the body.

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