29Si NMR, Sec and Ftir Studies of The Hydrolysis and Condensation of Si(OC2H5 )4 and Si2O(OC2H5)6

1986 ◽  
Vol 73 ◽  
Author(s):  
Chia-Cheng Lin ◽  
John D. Basil
Keyword(s):  
High Resolution ◽  
Ftir Spectroscopy ◽  
Size Exclusion Chromatography ◽  
Reaction Scheme ◽  
Size Exclusion ◽  
29Si Nmr ◽  
Reaction Products ◽  
Ftir Studies ◽  
Hydrolysis And Condensation ◽  
Exclusion Chromatography

ABSTRACTThe hydrolysis and initial condensation reactions of Si(OC2H5)4 and low order polyethoxysiloxanes have been studied with high resolution 29Si NMR and size exclusion chromatography/FTIR spectroscopy. The effects of various parameters such as H2O/TEOS mole ratio, catalyst, pH, solvent, temperature and aging have been observed in the different nature of the reaction products. The products include partially hydrolyzed and unhydrolyzed Si(OC2H5)4, Si2O(CH2H5)6, and Si3O2(OC2H5)8. The rate of formation and concentration of each product obtained under different conditions provides information about the reactivity of various silanol-containing species and the factors that affect the overall reaction scheme.

Monitoring the grafting of epoxidized natural rubber by size-exclusion chromatography coupled to FTIR spectroscopy

2003 ◽  
Vol 88 (10) ◽  
pp. 2539-2549 ◽  
Author(s):  
Andr� J. P. Van Zyl ◽  
Sven M. Graef ◽  
Ronald D. Sanderson ◽  
Bert Klumperman ◽  
Harald Pasch
Keyword(s):  
Natural Rubber ◽  
Ftir Spectroscopy ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Epoxidized Natural Rubber ◽  
Exclusion Chromatography

UNRAVELING THE MYSTERY OF NATURAL RUBBER BIOSYNTHESIS. PART II: COMPOSITION AND GROWTH OF IN VITRO NATURAL RUBBER USING HIGH-RESOLUTION SIZE EXCLUSION CHROMATOGRAPHY

2014 ◽  
Vol 87 (3) ◽  
pp. 451-458 ◽  
Author(s):  
Cheng Ching K. Chiang ◽  
Balaka Barkakaty ◽  
Judit E. Puskas ◽  
Wenshuang Xie ◽  
Katrina Cornish ◽  
...  
Keyword(s):  
High Resolution ◽  
Natural Rubber ◽  
Size Exclusion Chromatography ◽  
Rubber Tree ◽  
Size Exclusion ◽  
Common Source ◽  
Rubber Biosynthesis ◽  
Flight Mass Spectrometry ◽  
Exclusion Chromatography

ABSTRACT The superior properties of natural rubber (cis-1,4-polyisoprene [NR]) are a function of its structure and composition, properties that still remain a mystery and that are irreplaceable by any synthetic rubber. NR from guayule (Parthenium argentatum) has been gaining special interest for its hypoallergenic properties while maintaining superior mechanical properties that are commonly associated with the Brazilian rubber tree (Hevea brasiliensis), the most common source of NR. Techniques exist to isolate washed rubber particles (WRPs) that contain enzymatically active rubber transferase, to study NR biosynthesis, and previous work on the in vitro NR growth in Hevea has demonstrated the presence of around 50 wt% of a low molecular weight ([MW], Mn <10 000 g/mol) fraction. Structural and compositional analyses of this low MW fraction in Hevea are challenging due to the high protein content. We discuss the analysis and composition of guayule latex and WRPs using high-resolution Size Exclusion Chromatography. We also discuss the composition of the soluble fraction of inactive guayule latex using matrix-assisted laser desorption ionization/time of flight mass spectrometry.

UNRAVELING THE MYSTERY OF NATURAL RUBBER BIOSYNTHESIS. PART I: INVESTIGATION OF THE COMPOSITION AND GROWTH OF IN VITRO NATURAL RUBBER USING HIGH RESOLUTION SIZE EXCLUSION CHROMATOGRAPHY

2011 ◽  
Vol 84 (2) ◽  
pp. 166-177 ◽  
Author(s):  
Chengching K. Chiang ◽  
Wenshuang Xie ◽  
Colleen McMahan ◽  
Judit E. Puskas
Keyword(s):  
High Resolution ◽  
Natural Rubber ◽  
Size Exclusion Chromatography ◽  
Weight Fraction ◽  
Size Exclusion ◽  
Gravimetric Analysis ◽  
In Vitro Synthesis ◽  
Rubber Biosynthesis ◽  
Exclusion Chromatography

Abstract Monitoring the growth of in vitro natural rubber was accomplished by high resolution size exclusion chromatography, SEC. Washed rubber particles isolated from H. brasiliensis latex, containing the rubber transferase enzyme, were used to catalyze the polymerization of synthetic isopentenyl pyrophosphate monomer in the presence of farnesyl pyrophosphate initiator. The high-resolution SEC was able to detect the formation of new rubber. Changes in the low molecular weight fraction were also detected. Gravimetric analysis revealed ∼30% mass gain after the in vitro synthesis. The overall gel content was found to be reduced, which further supported the formation of new rubber. This is the first report that utilizes high-resolution SEC to monitor the in vitro NR growth without the use of radiolabeling.

scholarly journals Synthesis of Polysilsesquioxanes with Double-Decker Silsesquioxane Repeating Units

2016 ◽  
Vol 8 (2) ◽  
pp. 217-227 ◽  
Author(s):  
M. A. Hoque ◽  
Y. Kawakami
Keyword(s):  
Thermal Properties ◽  
Size Exclusion Chromatography ◽  
1H Nmr ◽  
Nitrogen Atmosphere ◽  
Size Exclusion ◽  
29Si Nmr ◽  
Air Atmosphere ◽  
Double Decker ◽  
Average Residual ◽  
Exclusion Chromatography

Polysilsesquioxanes were synthesized with end functional double-decker silsesquioxanes (DDSQ) and the polymers were characterized with 1H NMR, 29Si NMR and size exclusion chromatography (SEC). Polysilsesquioxane containing iso-butyl end capped DDSQ showed better solubility compared to that of methyl end capped DDSQ. Thermal properties investigated with TGA showed that the polymers exhibited exceptionally high stabilities in the range of 470-530°C even in both nitrogen and air atmosphere. The average residual weights of the polymers at 760°C were around 80% in the nitrogen atmosphere.

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