Characterization of the trans-structure in the molecular chain structure of natural rubber

2021 ◽  
pp. 131209
Author(s):  
Zechun Li ◽  
Changjin Yang ◽  
Yanchan Wei ◽  
Yuanbing Zhou ◽  
Shuangquan Liao
Keyword(s):  
Natural Rubber ◽  
Chain Structure ◽  
Molecular Chain ◽  
Trans Structure

Solid-State 13C NMR Characterization of Irradiation-Cross-Linked Natural Rubber

1987 ◽  
Vol 41 (3) ◽  
pp. 441-446 ◽  
Author(s):  
Dwight J. Patterson ◽  
Jack L. Koenig
Keyword(s):  
Solid State ◽  
Natural Rubber ◽  
Mobile Phase ◽  
Chain Scission ◽  
Structure Changes ◽  
Nmr Characterization ◽  
Cross Links ◽  
Gamma Irradiated ◽  
Trans Structure

Solid-state 13C NMR was used to characterize the structure changes produced in gamma irradiation in natural rubber. The structure of the irradiated natural rubber was found to be heterogeneous, consisting of a mobile phase and a semi-rigid phase. Cis-trans chain isomerization was detected in the mobile phase of the gamma-irradiated samples. The CP/MAS spectra of the more rigid phase contained resonances due to quaternary carbons arising from cross-links and vinyl end groups caused by main chain scission. The calculated values of β and G( X) agreed with earlier published results. Peroxide-cured natural rubber of an equivalent amount of network density showed a higher amount of trans structure than did the gamma-irradiated natural rubber.

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

scholarly journals Material parametrization of natural rubber based compound and characterization of crack propagation under consideration of dissipative effects

2021 ◽  
Author(s):  
Dan Pornhagen ◽  
Konrad Schneider ◽  
Markus Stommel
Keyword(s):  
Energy Dissipation ◽  
Crack Propagation ◽  
Natural Rubber ◽  
Experimental Tests ◽  
Material Behavior ◽  
Prony Series ◽  
Material Forces ◽  
Cracking Behavior ◽  
Dissipative Effects

AbstractMost concepts to characterize crack propagation were developed for elastic materials. When applying these methods to elastomers, the question is how the inherent energy dissipation of the material affects the cracking behavior. This contribution presents a numerical analysis of crack growth in natural rubber taking energy dissipation due to the visco-elastic material behavior into account. For this purpose, experimental tests were first carried out under different load conditions to parameterize a Prony series as well as a Bergström–Boyce model with the results. The parameterized Prony series was then used to perform numerical investigations with respect to the cracking behavior. Using the FE-software system ANSYS and the concept of material forces, the influence and proportion of the dissipative components were discussed.

Adhesion of Vulcanized Rubber Surfaces: Characterization of Unmodified and Electron Beam Modified EPDM Surfaces and Their Co-vulcanization with Natural Rubber

2009 ◽  
Vol 23 (13-14) ◽  
pp. 1763-1786 ◽  
Author(s):  
Ganesh C. Basak ◽  
Abhijit Bandyopadhyay ◽  
Y. K. Bharadwaj ◽  
S. Sabharwal ◽  
Anil K. Bhowmick
Keyword(s):  
Electron Beam ◽  
Natural Rubber ◽  
Vulcanized Rubber

scholarly journals Multiblock Copolymers of Norbornene and Cyclododecene: Chain Structure and Properties

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1756
Author(s):  
Yulia I. Denisova ◽  
Georgiy A. Shandryuk ◽  
Marianna P. Arinina ◽  
Ivan S. Levin ◽  
Vsevolod A. Zhigarev ◽  
...  
Keyword(s):  
First Generation ◽  
Average Length ◽  
Chain Structure ◽  
Random Copolymers ◽  
Multiblock Copolymers ◽  
Structure Property ◽  
Reaction Conditions ◽  
Property Relations ◽  
Cross Metathesis

We investigate the structure–property relations of the multiblock copolymers of norbornene with cyclododecene synthesized via the macromolecular cross-metathesis reaction between amorphous polynorbornene and semicrystalline polydodecenamer in the presence of the first-generation Grubbs catalyst. By adjusting the reaction time, catalyst amount, and composition of the initial system, we obtain a set of statistical multiblock copolymers that differ in the composition and average length of norbornene and dodecenylene unit sequences. Structural, thermal, and mechanical characterization of the copolymers with NMR, XRD, DSC (including thermal fractionation by successive self-nucleation and annealing), and rotational rheology allows us to relate the reaction conditions to the average length of crystallizable unit sequences, thicknesses of corresponding lamellas, and temperatures of their melting. We demonstrate that isolated dodecenylene units can be incorporated into crystalline lamellas so that even nearly random copolymers should retain crystallinity. Weak high-temperature endotherms observed in the multiblock copolymers of norbornene with cyclododecene and other cycloolefins could indicate that the corresponding systems are microphase-separated in the melt state.

Synthesis and characterization of novel natural rubber based cationic waterborne polyurethane-Effect of emulsifier and diol class chain extender

2017 ◽  
Vol 135 (3) ◽  
pp. 45715 ◽  
Author(s):  
Nathapong Sukhawipat ◽  
Nitinart Saetung ◽  
Jean-Francois Pilard ◽  
Sophie Bistac ◽  
Anuwat Saetung
Keyword(s):  
Natural Rubber ◽  
Waterborne Polyurethane ◽  
Chain Extender ◽  
Synthesis And Characterization ◽  
Cationic Waterborne Polyurethane
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