Applications of a recycled-flow Fourier transform nuclear magnetic resonance system: molecular weight determination of siloxane polymers by silicon-29 NMR

1986 ◽  
Vol 19 (8) ◽  
pp. 2295-2300 ◽  
Author(s):  
David A. Laude ◽  
Charles L. Wilkins
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Magnetic Resonance ◽  
Molecular Weight Determination ◽  
Resonance System ◽  
Magnetic Resonance System ◽  
Siloxane Polymers ◽  
Nuclear Magnetic

scholarly journals Cleavage of the Graft Bonds in PVDF–g–St Films by Boiling Xylene Extraction and the Determination of the Molecular Weight of the Graft Chains

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1098 ◽  
Author(s):  
Chen ◽  
Seko
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Thermal Degradation ◽  
Gel Permeation Chromatography ◽  
Extraction Time ◽  
Gel Permeation ◽  
Irradiation Graft ◽  
Nuclear Magnetic

To determine the molecular weight of graft chains in grafted films, the polystyrene graft chains of PVDF–g–St films synthesized by a pre-irradiation graft method are cleaved and separated by boiling xylene extraction. The analysis of the extracted material and the residual films by FTIR, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) analyses indicates that most graft chains are removed from the PVDF–g–St films within 72 h of extraction time. Furthermore, the molecular weight of the residual films decreases quickly within 8 h of extraction and then remains virtually unchanged up to 72 h after extraction time. The degradation is due to the cleavage of graft bonds, which is mainly driven by the thermal degradation and the swelling of graft chains in solution. This allows determination of the molecular weight of graft chains by GPC analysis of the extracted material. The results indicate that the PVDF–g–St prepared in this study has the structure where one or two graft chains hang from each PVDF backbone.

Quantum Factorization of 143 on a Dipolar-Coupling Nuclear Magnetic Resonance System

2012 ◽  
Vol 108 (13) ◽  
Author(s):  
Nanyang Xu ◽  
Jing Zhu ◽  
Dawei Lu ◽  
Xianyi Zhou ◽  
Xinhua Peng ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Dipolar Coupling ◽  
Resonance System ◽  
Magnetic Resonance System ◽  
Nuclear Magnetic
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