NMR characterization of elastomers reinforced with in situ precipitated silica

1991 ◽  
Vol 24 (14) ◽  
pp. 4067-4072 ◽  
Author(s):  
Leoncio Garrido ◽  
James E. Mark ◽  
Chen C. Sun ◽  
Jerome L. Ackerman ◽  
Chen Chang
Keyword(s):  
Precipitated Silica ◽  
Nmr Characterization

Vanadia Gel Synthesis via Peroxovanadate Precursors. 1. In Situ Laser Raman and51V NMR Characterization of the Gelation Process

2000 ◽  
Vol 104 (49) ◽  
pp. 11622-11631 ◽  
Author(s):  
Craig J. Fontenot ◽  
Jerzy W. Wiench ◽  
M. Pruski ◽  
G. L. Schrader
Keyword(s):  
Gelation Process ◽  
Laser Raman ◽  
Nmr Characterization

Reinforcement from In-Situ Precipitated Silica in Polysiloxane Elastomers under Various Types of Deformation

1992 ◽  
Vol 274 ◽  
Author(s):  
James E. Mark ◽  
Shuhong Wang ◽  
Ping Xu ◽  
Jianye Wen
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Elongation ◽  
Compression Set ◽  
Precipitated Silica ◽  
Equilibrium Swelling ◽  
Rupture Energy ◽  
End Linking ◽  
Reinforcing Effects

ABSTRACTElastomeric networks prepared by tetrafunctionally end linking hydroxyl-terminated poly(dimethylsiloxane) chains (PDMS) were filled by the in-situ precipitation of silica. The resulting networks were investigated under uniaxial elongation, biaxial extension, shear, and torsion in order to characterize the resulting changes in mechanical properties. Compared with the unfilled networks, the silica-filled materials showed large reinforcing effects. Specifically, their values of the modulus, ultimate strength, and rupture energy increased significantly. The results thus indicate that the PDMS networks filled by the in-situ precipitation of silica have very good mechanical properties in several, rather different deformations. Examples of other deformations of interest are equilibrium swelling, and dynamic cycling for characterization of compression set.

scholarly journals Unambiguous Ex Situ and in Cell 2D 13C Solid-State NMR Characterization of Starch and Its Constituents

2018 ◽  
Vol 19 (12) ◽  
pp. 3817 ◽  
Author(s):  
Alexandre Poulhazan ◽  
Alexandre Arnold ◽  
Dror Warschawski ◽  
Isabelle Marcotte
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Amylose Content ◽  
Amorphous State ◽  
Ex Situ ◽  
Starch Structure ◽  
Nmr Characterization ◽  
Crystalline Domains

Starch is the most abundant energy storage molecule in plants and is an essential part of the human diet. This glucose polymer is composed of amorphous and crystalline domains in different forms (A and B types) with specific physicochemical properties that determine its bioavailability for an organism, as well as its value in the food industry. Using two-dimensional (2D) high resolution solid-state nuclear magnetic resonance (SS-NMR) on 13C-labelled starches that were obtained from Chlamydomonas reinhardtii microalgae, we established a complete and unambiguous assignment for starch and its constituents (amylopectin and amylose) in the two crystalline forms and in the amorphous state. We also assigned so far unreported non-reducing end groups and assessed starch chain length, crystallinity and amylose content. Starch was then characterized in situ, i.e., by 13C solid-state NMR of intact microalgal cells. Our in-cell methodology also enabled the identification of the effect of nitrogen starvation on starch metabolism. This work shows how solid-state NMR can enable the identification of starch structure, chemical modifications and biosynthesis in situ in intact microorganisms, eliminating time consuming and potentially altering purification steps.

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