Network characterisation of end-linked poly(dimethylsiloxane) by 1H-NMR-spin-spin relaxation

Simon, Géza; Birnstiel, A.; Schimmel, K.-H.

doi:10.1007/bf00266179

Cited by 42 publications

(20 citation statements)

References 6 publications

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“…The results presented above confirm that the signal in PDMS networks may be analyzed in two components. ,− This was already observed by 1 H NMR in similar PDMS networks . The component relaxing slower may be clearly attributed to dangling chains, as shown in ref .…”

Section: Discussionsupporting

confidence: 85%

Local Order and Induced Orientation in PDMS Model Networks, Studied by ²H NMR

Sotta

1998

Macromolecules

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2H NMR experiments in a series of poly(dimethylsiloxane) end-linked networks are presented. The 2H NMR line shape in the relaxed state consists of a pseudo-solid contribution, with nonzero residual interactions, and a liquid contribution, with no residual interactions. The liquid part is attributed to dangling chains. The magnitude of residual interactions in the pseudo-solid part (elastic chains) is compared to the magnitude of the uniaxial order induced upon stretching uniaxially the networks. The induced order is measured by the splitting of the doublet which appears upon stretching. The splitting correlates also well with the polymer network volume fraction at swelling equilibrium. All these quantities are related to the properties of effectively elastic chains in the networks. The presence of dangling chains does not modify the interpretation given previously for the induced uniaxial order, in terms of a mean orientational field. The analysis which is presented allows one to estimate the strength of orientational interactions between segments.

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Section: Discussionsupporting

confidence: 85%

Local Order and Induced Orientation in PDMS Model Networks, Studied by ²H NMR

Sotta

1998

Macromolecules

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“…It is therefore important when developing such sensors, that there are a range of safe and repeatable reference samples to aid in calibration and testing. For the spin-spin relaxation times different viscosities of polydimethylsiloxane (PDMS) oil provide a suitable range of safe test materials [4,5]. However, for the spin-lattice relaxation times, available options are not as safe to use and typically consist of different concentrations of Nickel Sulphate, which is carcinogenic and toxic or Copper Sulfate solutions [6,7].…”

Section: Introductionmentioning

confidence: 99%

Novel Food-Safe Spin-Lattice Relaxation Time Calibration Samples for Use in Magnetic Resonance Sensor Development

Almazrouei

Newton

Dye

et al. 2017

The 4th International Electronic Conference on Sensors and Applications

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Magnetic Resonance (MR) sensors are an area of increasing interest for the measurement and monitoring of material properties. There are two relaxation times associated with samples that can be measured with MR sensors: The spin-lattice and spin-spin relaxations. When developing new sensors, it is desirable to have a series of standards by which instruments can be assessed. The standard calibration materials available typically comprise different concentrations of Nickel Sulphate which is carcinogenic and toxic. In this work we report the use of solutions containing full fat milk powder as a safe and inexpensive material that shortens the longitudinal relaxation time of water over a wide range of values. We demonstrate that concentrations in distilled water from 5% w/v to 64% w/v give T1 values from 1.7 s down to 469 ms respectively in a 1.5T clinical MRI, while within an MR sensor these times were from 1.6 s down to 431 ms. In addition, both systems have the same exponential coefficient (−0.022× concentration) that demonstrates the effectiveness of the NMR sensor in comparison to the clinical MRI.

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“…The filler aggregates, which are covered by the interface, can be considered as multifunctional, physical cross-links, which provide a significant amount of physical adsorption network junctions for the elastomer matrix . The density of these physical junctions was determined for silica filled PDMS. , The NMR method has also been used for a quantitative determination of the density of chemical cross-links in unfilled and filled rubber networks ,− and chain entanglements …”

Section: Introductionmentioning

confidence: 99%

EPDM−Carbon Black Interactions and the Reinforcement Mechanisms, As Studied by Low-Resolution¹H NMR

1999

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Proton, low-resolution T 2 NMR relaxation experiments are used to study the adsorption of EPDM to the surface of carbon blacks and the structure of the physical EPDM/carbon black network in cured and uncured compounds. It is shown that a layer of immobilized EPDM is formed at the carbon black surface after mixing. The estimated thickness of the interfacial EPDM is in the range of one to two diameters of the monomer unit (≈1 nm). At temperatures of up to 160 °C, the mobility of EPDM chain units in the interface is strongly hindered and is comparable to that in an unfilled EPDM at temperatures 10−15 deg above T g. It is suggested that the sites of the interaction between the carbon black and the EPDM cause physical adsorption network junctions in the rubber matrix. The average molar mass of EPDM chains between the adjacent adsorption junctions in bound EPDM rubber is about 1800−2500 g/mol and depends on the content and the type of the filler. The mean end-to-end distance between the adsorption junctions is comparable to the average distance between the adjacent carbon black aggregates. This suggests that the carbon black aggregates are interconnected by EPDM bridging chains, and a continuous EPDM/carbon black physical network is formed in the bound rubber fraction of the compound. The results obtained for uncured filled rubbers provide strong evidence of a “bimodal” structure of the physical network. The two types of EPDM chains and/or chain fragments, which have strongly different densities of EPDM−carbon black adsorption junctions, are present in the elastomer matrix outside of the EPDM − carbon black interface. There is an EPDM fraction that is loosely bound to the carbon black by adsorption interactions. This loosely bound rubber has numerous adsorption network junctions, similar to those of the bound rubber. The other fraction of EPDM, the extractable (unbound) rubber, has a relatively low number of adsorption network junctions and can apparently be extracted from the compound. The fraction of loosely bound EPDM chains, as measured by NMR, increases as the maximum possible EPDM−carbon black contact area per unit volume of the elastomer increases, regardless of the type of carbon black, and is relatively close to the content of the bound rubber. Results of mechanical property tests on the carbon black filled vulcanisates reveal that several factors contribute to the reinforcing effect of the filler. Besides the hydrodynamic effects, the occluded EPDM, the chemical cross-links, and the formation of the physical EPDM−carbon black network, the filler−filler interactions provide a significant contribution to the modulus in the low-strain region, while they are broken at high strains.

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Network characterisation of end-linked poly(dimethylsiloxane) by 1H-NMR-spin-spin relaxation

Cited by 42 publications

References 6 publications

Local Order and Induced Orientation in PDMS Model Networks, Studied by ²H NMR

Local Order and Induced Orientation in PDMS Model Networks, Studied by ²H NMR

Novel Food-Safe Spin-Lattice Relaxation Time Calibration Samples for Use in Magnetic Resonance Sensor Development

EPDM−Carbon Black Interactions and the Reinforcement Mechanisms, As Studied by Low-Resolution¹H NMR

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Network characterisation of end-linked poly(dimethylsiloxane) by 1H-NMR-spin-spin relaxation

Cited by 42 publications

References 6 publications

Local Order and Induced Orientation in PDMS Model Networks, Studied by 2H NMR

Local Order and Induced Orientation in PDMS Model Networks, Studied by 2H NMR

Novel Food-Safe Spin-Lattice Relaxation Time Calibration Samples for Use in Magnetic Resonance Sensor Development

EPDM−Carbon Black Interactions and the Reinforcement Mechanisms, As Studied by Low-Resolution1H NMR

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Product

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Local Order and Induced Orientation in PDMS Model Networks, Studied by ²H NMR

Local Order and Induced Orientation in PDMS Model Networks, Studied by ²H NMR

EPDM−Carbon Black Interactions and the Reinforcement Mechanisms, As Studied by Low-Resolution¹H NMR