New aspects of transversal1H-NMR relaxation in natural rubber vulcanizates

Heuert, U.; Knörgen, M.; Menge, H.; Scheler, G.; Schneider, H.

doi:10.1007/bf00556810

Cited by 42 publications

(56 citation statements)

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“…The present study focuses on estimation of the sol fraction and crosslink density of reclaimed GTR for the purpose of further analysis by Horikx's theory. While there are newer methods for determining the crosslink density, swelling measurements were used in this study since they are still widely used in literature and have been shown to be consistent with NMR methods when the Kraus correction is taken into account . Based on refined measurement methods for estimating the sol fraction of the polymer component of GTR, a quantitative selectivity parameter (based on Horikx's theory) is proposed for crosslink scission in devulcanization processes.…”

Section: Introductionmentioning

confidence: 99%

Quantifying and comparing the selectivity for crosslink scission in mechanical and mechanochemical devulcanization processes

Edwards

Danon

Gryp

et al. 2016

J of Applied Polymer Sci

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Devulcanization processes have potential to increase the economic value of ground tire rubber (GTR) derived from waste tires, although the chemistry of the devulcanization process is still poorly understood. This article presents a method, based on sol extraction and swelling measurements, for quantifying the selectivity for crosslink scission over main chain scission, and applies it to extrusion-based mechanical and mechanochemical devulcanization processes at various operating conditions. The mechanochemical devulcanization process, using diphenyl disulfide and process oil, resulted in a higher selectivity for crosslink scission than the mechanical devulcanization process. Furthermore, it was shown that the process oil, along with lower reaction temperature, in the mechanochemical devulcanization process was responsible for the increased selectivity, rather than the presence of diphenyl disulfide.

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Section: Introductionmentioning

confidence: 99%

Quantifying and comparing the selectivity for crosslink scission in mechanical and mechanochemical devulcanization processes

Edwards

Danon

Gryp

et al. 2016

J of Applied Polymer Sci

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“…NMR spectroscopy is a powerful tool for studying the structure and dynamics of a variety of polymer systems such as elastomers, filled rubbers, polymer melts, and block copolymers . The traditional transverse 1 H‐NMR relaxation was recently complemented by multiple quantum nuclear magnetic resonance method (MQ NMR), whose application to unfilled and filled rubbers was extensively described by Valentin .…”

Section: Introductionmentioning

confidence: 99%

Probing small network differences in sulfur‐cured rubber compounds by combining nuclear magnetic resonance and swelling methods

Dibbanti

Mauri

et al. 2015

J of Applied Polymer Sci

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We studied the network structure of elastomers based on polyisoprene, polybutadiene, and their blends in the narrow range of formulations compatible with actual use in the automotive tyre industry. Cross‐link density (CLD) was quantified comparatively by low‐field 1H multiple quantum time domain nuclear magnetic resonance (MQ TD‐NMR) and by equilibrium swelling technique. The robustness and agreement of the two methods was demonstrated in measuring minute alterations of unfilled vulcanizates beyond the optimum cure time. Comparison with samples where polysulfidic bonds were selectively cleaved also demonstrates that the length of the sulfur chain constituting the cross‐link does not significantly affect residual dipolar coupling. Kraus, Lorenz, and Parks correction for filler restriction on swelling is validated by MQ TD‐NMR, which also allows extracting information on cross‐link distribution not provided by swelling measurement. Cross‐link distributions in the blends were demonstrated to be significantly different from the weighted average of the pure samples, while average proton–proton residual dipolar coupling values correspond. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42700.

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“…e formula for the decay process of magnetization with time (t) during the relaxation process is shown as follows [18]:…”

Section: Nmr (Nuclear Magnetic Resonance) Analysismentioning

confidence: 99%

Research on Recovery Mechanism and Process of Waste Thermosetting Phenolic Resins Based on Mechanochemical Method

Dong

Song

2020

Advances in Materials Science and Engineering

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The present study analyzed the recovery mechanism of the thermosetting phenolic resin waste, optimizing the recovery process parameters, based on the mechanochemical recovery method. The physical and chemical structure of the ultrapulverized phenolic resin powder was characterized by the low-field NMR (nuclear magnetic resonance), IR (infrared spectroscopy), and SEM (scanning electron microscopy). The recovery process parameters were designed by using the response surface analysis method, and the multiple quadratic regression model was established and the multiobjective process parameter was optimized. The results show that the body network structure of the material is destroyed during the crushing process. The intensity of the internal cross-linking signal is reduced and tends to be stable at about 60%, when the particle size exceeds 120 mesh. The cross-linking bonds methylene (-CH2-) in the main chain of the molecular chain and the C-O bond in the methylol group on the branch are broken. The tensile strength of the recycled sheet made of the phenolic resin powder is 8.27 MPa, and the bending strength is 17.76 Mpa through the mechanical properties test. The influences on the change rate of the cross-linking signal intensity and the yield of the recycled powder are in the following order: rotation speed, feed size, time, and feed volume. The best recovery parameters are as follows: rotation speed of 2820 r/min, time of 80 min, feed particle diameter of 0.43 mm, and feed volume of 60 g.

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New aspects of transversal1H-NMR relaxation in natural rubber vulcanizates

Cited by 42 publications

References 0 publications

Quantifying and comparing the selectivity for crosslink scission in mechanical and mechanochemical devulcanization processes

Quantifying and comparing the selectivity for crosslink scission in mechanical and mechanochemical devulcanization processes

Probing small network differences in sulfur‐cured rubber compounds by combining nuclear magnetic resonance and swelling methods

Research on Recovery Mechanism and Process of Waste Thermosetting Phenolic Resins Based on Mechanochemical Method

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