Molecular Mobility in Ultrasonically Devulcanized Unfilled Butadiene Rubber

2004 ◽  
Vol 77 (4) ◽  
pp. 745-758 ◽  
Author(s):  
Jeong Seok Oh ◽  
A. I. Isayev ◽  
E. von Meerwall
Keyword(s):  
Silicone Rubber ◽  
Mean Diffusivity ◽  
Nmr Relaxation ◽  
Butadiene Rubber ◽  
Nmr Studies ◽  
Transverse Relaxation ◽  
Gradient Diffusion ◽  
Before And After ◽  
Rubber Recycling ◽  
Crosslinked Networks

Abstract We have used NMR relaxation and pulsed-gradient diffusion measurements at 70 °C in unfilled butadiene rubber (BR) before and after crosslinking, and after subsequent devulcanization by intense ultrasound. In an effort to support this method of rubber recycling, characterization has been performed at the molecular level. The transverse relaxation (T2) decay was successfully described using a three-component model. The components are attributed to entangled and crosslinked networks; light sol and dangling network fragments; and partially unreactive oligomers. All component molecular mobilities and the relative contributions of the components to the echo were investigated. Devulcanization decreases the diffusivity of the oligomer remnants and increases mean diffusivity of the light sol. The additional amount of extractable sol produced by devulcanization of BR is more than that of silicone rubber, indicating that the ultrasonic devulcanization of BR is more efficient than that of silicone rubber. The present results are compared with our previous NMR studies of devulcanized rubbers.

Ultrasound Devulcanization of SBR: Molecular Mobility of Gel and Sol

1997 ◽  
Vol 70 (2) ◽  
pp. 183-193 ◽  
Author(s):  
S. T. Johnston ◽  
J. Massey ◽  
E. von Meerwall ◽  
S. H. Kim ◽  
V. Yu Levin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Main Chain ◽  
Molecular Level ◽  
Spin Echo ◽  
Mean Diffusivity ◽  
Nmr Relaxation ◽  
Butadiene Rubber ◽  
Ultrasound Technique ◽  
Large Molecules ◽  
Nmr Methods

Abstract In an effort to support the recycling of rubbery polymers and composites, 1H NMR relaxation and pulsedgradient spin echo diffusion measurements have been performed on virgin and unfilled vulcanized strene-butadiene rubber (SBR), and networks after various extents of devulcanization using an ultrasound technique. The NMR methods recognize unentangled light molecules (e.g. sol), but do not distinguish between unattached entangled large molecules and chemical network segments. Devulcanization generates additional sol with a wide mass distribution, thus increasing both sol and gel mobility, but decreasing sol mean diffusivity. The latter effect is accounted for by the increasing mean sol molecular mass but also by the increasing glass transition temperature, which is related to main-chain stiffening seen in our earlier 13C NMR experiments. In addition to improving the molecular-level understanding of devulcanization, this study provides guidance for the optimization of the devulcanization parameters.

scholarly journals Investigation of Hydrothermally Stressed Silicone Rubber/Silica Micro and Nanocomposite for the Coating High Voltage Insulation Applications

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3567
Author(s):  
Faiza Faiza ◽  
Abraiz Khattak ◽  
Safi Ullah Butt ◽  
Kashif Imran ◽  
Abasin Ulasyar ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Structural Changes ◽  
Polymer Chains ◽  
Hydrothermal Conditions ◽  
Silica Filler ◽  
Before And After ◽  
Aging Conditions ◽  
The Stability ◽  
Micro Silica ◽  
Applied Stresses

Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

THERMOPHYSICAL AND DYNAMIC PROPERTIES OF BUTADIENE-NITRILE RUBBER FILLED WITH ULTRA HIGH-MOLECULAR WEIGHT POLYETHYLENE

2021 ◽  
Vol 0 (2) ◽  
pp. 36-43
Author(s):  
N.V. Shadrinov ◽  
◽  
A.A. Khristoforova ◽  
Keyword(s):  
Molecular Weight ◽  
Dynamic Properties ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Physicomechanical Properties ◽  
Butadiene Rubber ◽  
Rubber Compounds ◽  
Ultrahigh Molecular Weight ◽  
Before And After ◽  
Butadiene Nitrile Rubber ◽  
Ultra High Molecular Weight

The results of the study of the complex of properties of an elastomeric composite material based on nitrile butadiene rubber BNKS-18 and ultrahigh molecular weight polyethylene are presented. The effect of UHMWPE on the vulcanization characteristics of rubber compounds, the physicomechanical properties of vulcanizates before and after thermal aging in a hydrocarbon environment and air, and also on the dynamic properties before and after curing are investigated.

Na+ alters the affinity for glucose and phosphate in rat renal brush-border membranes: a study of NMR relaxation rates

1992 ◽  
Vol 263 (2) ◽  
pp. C509-C515
Author(s):  
M. Barac-Nieto ◽  
S. M. Liu ◽  
R. K. Gupta
Keyword(s):  
Magnetic Field ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Substrate Binding ◽  
Nmr Relaxation ◽  
Membrane Vesicles ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Rapid Exchange ◽  
Renal Brush Border Membranes

Transport of D-glucose (Glc) and Pi across renal microvilli brush-border membrane vesicles (BBMV) is coupled to Na+.Na+ may alter substrate binding and dissociation or the mobility of the translocator and its complexes. To evaluate substrate binding in NaCl or KCl solutions containing BBMV, we measured nuclear magnetic resonance transverse relaxation rates (1/T2) of [1-13C]Glc and 31P(i), as well as their temperature, magnetic field, and pH dependencies. The data indicate the following: 1) the alpha-anomer, but not the beta-anomer, of Glc binds to BBMV, more in the presence of Na+ than of K+; 2) interactions of P(i) with BBMV that increase its 1/T2 are significant in the presence of K+ but not of Na+; 3) temperature and magnetic field dependencies of the 1/T2 of P(i) bound to BBMV are consistent with more rapid exchange with free P(i) in the presence of Na+ than of K+; and 4) in the presence of Na+, [H+] promoted interactions of P(i) with BBMV that increase its 1/T2, probably by interfering with formation of rapidly dissociating Na(+)-P(i)-carrier complexes. In conclusion, Na+ promotes association of alpha-Glc to BBMV but promotes rapid exchange and dissociation of P(i) from BBMV. In both cases, Na+ effects coupling by altering the affinity of the cotransporters for the substrate.

UV Weathering Effect on Antibacterial Performance in Silicone Rubber Compounds

2011 ◽  
Vol 410 ◽  
pp. 325-328
Author(s):  
Kulnida Taptim ◽  
Narongrit Sombatsompop
Keyword(s):  
Antibacterial Activity ◽  
Silicone Rubber ◽  
Uv Light ◽  
Inhibition Zone ◽  
Uv Aging ◽  
Antibacterial Performance ◽  
Rubber Compounds ◽  
Quinoline Carboxylic Acid ◽  
Different Types ◽  
Before And After

Silicone rubber compounded with three different types of antibacterial agents: namely; nanoAg colloids, Silver substituted Zeolite compound (SSZ) and 2-Hydroxypropyl-3-Piperazinyl-Quinoline Carboxylic Acid Methacrylate (HPQM) were prepared and changes in antibacterial performance were assessed before and after exposure to UV light at different aging times. Drop plate and halo tests were performed to study the antibacterial performance of silicone rubber compounds. The results indicated that antibacterial activity of silicone compound changed when the UV aging time was increased. The antibacterial activity of the rubber added with HPQM extremely decreased considered by the inhibition zone and %reductions of Staphylococcus aureus and Escherichia coli bacteria for any given contact times. On the other hand, the UV light did not affect the antibacterial activity of silicone rubber compounds added with nanoAg colloids and SSZ agents.

NMR studies of hydrocarbons solubilized in aqueous micellar solutions

1991 ◽  
Vol 69 (5) ◽  
pp. 822-833 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Jan C. T. Kwak ◽  
Zhisheng Gao ◽  
Elisabeth Verpoorte ◽  
J. Bruce MacDonald ◽  
...  
Keyword(s):  
Alkyl Chain ◽  
Chemical Shifts ◽  
Nmr Relaxation ◽  
Spin Lattice Relaxation ◽  
Ionic Surfactant ◽  
Nmr Studies ◽  
Unsaturated Hydrocarbons ◽  
Saturated Hydrocarbons ◽  
Surfactant Micelle ◽  
H Nmr

Information concerning the solubilization of hydrocarbons in ionic surfactant micelles was obtained from 2H NMR relaxation, 1H NMR chemical shifts, and 1H NMR paramagnetic relaxation measurements. The rotational motion of deuterated hydrocarbons, which is related to the micellar microviscosity at the location of the hydrocarbons, was probed by 2H NMR relaxation. The relaxation data are interpreted using both the two-step and the single-step models, and the results are discussed in terms of the micellar microviscosity and the location of the hydrocarbons in micelles. The location of the hydrocarbons in micelles was further investigated by determining the aromatic ring current-induced 1H chemical shifts along the surfactant alkyl chain and by comparing the 1H spin-lattice relaxation enhancement of the hydrocarbons and the surfactant alkyl chain, induced by Mn2+ on the micellar surface. The hydrocarbons used include benzene, naphthalene, acenaphthalene, triphenylene, cyclohexane, cyclododecane, and tert-butylcyclohexane and the surfactants studied are hexadecyl-, tetradecyl-, and dodecyltrimethylammonium bromide; hexadecyl-, tetradecyl-, and dodecylpyridinium halide; and sodium dodecyl sulfate. The results indicate that the micellar microviscosity at the location of saturated hydrocarbons is approximately 5 cP for both the cationic and anionic micelles, whereas the micellar microviscosity at the location of unsaturated hydrocarbons is much higher. The unsaturated hydrocarbons are found to reside primarily near the surfactant headgroup in the cationic micelles, but are distributed evenly throughout the anionic SDS micelles. The saturated hydrocarbons appear to be located in the interior of the micelles. Key words: NMR, relaxation, solubilization, surfactant, micelle.

1H nuclear magnetic resonance relaxometric characterization of fat and water states in soft and hard cheese

2000 ◽  
Vol 67 (4) ◽  
pp. 609-618 ◽  
Author(s):  
BEATRICE CHALAND ◽  
FRANÇOIS MARIETTE ◽  
PHILIPPE MARCHAL ◽  
JACQUES DE CERTAINES
Keyword(s):  
Milk Fat ◽  
Nmr Relaxation ◽  
Transverse Relaxation ◽  
Anhydrous Milk Fat ◽  
Solid Ratio ◽  
Nmr Relaxometry ◽  
1H Nuclear Magnetic Resonance ◽  
Relaxation Component ◽  
Hard Cheese

The aim of this work was to study the spin–spin (T2) relaxation components of one hard cheese and three soft cheeses to characterize fat and water states. NMR signals were measured at 6 °C with a 0·47 T NMR device. The transverse relaxation decay was fitted using the Marquardt method. The T2 relaxometric behaviour of the cheeses under consideration was characterized by four relaxation components. To understand the chemical composition of each NMR component, we studied anhydrous milk fat extracted from each cheese analysed. At 6 °C, the fat was 60% crystalline. In cheese, the solid fat was found mainly in the shorter relaxation component with a T2 of 17 μs. The intensity of the NMR relaxation with a T2 > 1 ms was explained by the amount of water, liquid fat and proteins, and the associated relaxation time varied as a function of the process used. The composition of each relaxation component was confirmed by the temperature effect and the influence of the fat content on the NMR cheese signal. NMR relaxometry was able to provide information on water behaviour (i.e. the quantity and level of interactions with proteins) and on the solid[ratio ]liquid ratio of anhydrous milk fat in the cheese.

scholarly journals Enhanced Hydrofobicity of Polymers for Personal Protective Equipment Achieved by Chemical and Physical Modification

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 106
Author(s):  
Emilia Irzmańska ◽  
Ewa Korzeniewska ◽  
Ryszard Pawlak ◽  
Mariusz Tomczyk ◽  
Aleksandra Smejda-Krzewicka ◽  
...  
Keyword(s):  
Contact Angle ◽  
Silicone Rubber ◽  
Pulse Repetition Frequency ◽  
Surface Condition ◽  
Scanning Speed ◽  
Beam Power ◽  
Laser Surface Modification ◽  
Power Pulse ◽  
Nanosecond Pulsed Laser ◽  
Before And After

The article presents significant results in research on creating superhydrophobic properties of materials which can be used as an interesting material for use in self-cleaning polymer protective gloves and similar applications where the superhydrophobicity plays a significant role. In this work the influence of laser surface modification of MVQ silicone rubber was investigated. The research was conducted using a nanosecond-pulsed laser at 1060 nm wavelength. After a process of laser ablation, the surface condition was examined using a SEM microscope and infrared spectroscopy. During the tests, the contact angle was checked both before and after the laser modification of samples pre-geometrised in the process of their production. The test results presented in the paper indicate that the chemical and physical modifications contribute to the change in the MVQ silicone rubber contact angle. A significant increase (by more than 30°) in the contact angle to 138° was observed. It was confirmed that surface geometrisation is not the only factor contributing to an increase in the contact angle of the analyzed material; other factors include a change in laser texturing parameters, such as mean beam power, pulse duration, scanning speed and pulse repetition frequency.

scholarly journals Laser-Textured Rubbers with Carbon Nanotube Fillers

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1091 ◽  
Author(s):  
Mariusz Siciński ◽  
Ewa Korzeniewska ◽  
Mariusz Tomczyk ◽  
Ryszard Pawlak ◽  
Dariusz Bieliński ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Surface Condition ◽  
Pulsed Laser ◽  
Contact Angles ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Vulcanized Rubber ◽  
Nanosecond Pulsed Laser ◽  
Before And After ◽  
Styrene Butadiene

This paper describes a method of laser ablation for improving the hydrophobic properties of vulcanized rubber. The treatment was tested on acrylonitrile rubber (NBR) and styrene butadiene rubber (SBR) containing carbon nanotubes and soot as fillers. The surface layer of the vulcanizates was modified using a nanosecond-pulsed laser at 1060 nm wavelength. The parameters of the ablation process were congruent, so no chemical changes in the polymeric material were observed. Evaluation of the surface condition of the laser-textured samples was performed using a Leica MZ6 stereoscopic microscope, operating with MultiScan 8.0 image analysis software. The contact angles were determined for all the samples before and after the surface modification process. Following modification of the surface morphology, with the best parameters of laser ablation, the contact angle increased, reaching 147°, which is very close to the threshold of superhydrophobicity (150°). On the basis of the results from several tests, laser ablation with a fiber-pulsed laser can be considered a very useful method for producing rubbers with superhydrophobic surfaces.

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