scholarly journals Simultaneous DSC-FTIR spectroscopy: Comparison of cross-linking kinetics of an epoxy/amine resin system

2012 ◽  
Vol 543 ◽  
pp. 9-17 ◽  
Author(s):  
Surya D. Pandita ◽  
Liwei Wang ◽  
Ramani S. Mahendran ◽  
Venkata R. Machavaram ◽  
Muhammad S. Irfan ◽  
...  
2014 ◽  
Vol 881-883 ◽  
pp. 905-908
Author(s):  
Li Wei Wang ◽  
Gerard F. Fernando

The cross-linking kinetics of an epoxy/amine resin system was studied using the conventional DSC and FTIR spectroscopy, respectively. Conventional DSC was modified to accommodate two fibre optic probes which could be used to monitor the spectra of epoxy/amine resin system during cure. The cross-linking kinetics for the epoxy/amine resin system obtained via the conventional DSC and FTIR and simultaneous DSC/FTIR were similar. The feasibility of using a simple bifurcated fibre optic probe to link the DSC to the FTIR spectrometer was demonstrated.


2006 ◽  
Vol 71 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Yuanhua Sun ◽  
Tonglai Zhang ◽  
Jianguo Zhang ◽  
Xiaojing Qiao ◽  
Li Yang ◽  
...  

A "snapshot" simulation of the surface reaction zone is captured by a thin film of material heated rapidly to temperatures characteristic of the burning surface by using the T-jump/FTIR spectroscopy. The time-to-exotherm (tx) kinetics method derived from the control voltage trace of the Pt filament can be introduced to resolve the kinetics of an energetic material owing to its high sensitivity to the thermochemical reactions. The kinetic parameters of the two title compounds are determined under different pressures. The results show that Li(NTO)·2H2O and Na(NTO)·H2O (NTO = anion of 3-nitro-1,2,4-triazol-5-one) exhibit weak pressure dependence, their decomposition is dominated by the condensed phase chemistry irrespective of the pressure in the 0.1-1.1 MPa range. The values of Ea determined here are smaller than those given by a traditional non-isothermal differential scanning colorimetry (DSC) method, which might be resembled as the surface of explosion more closely and enabled the pyrolysis surface to be incorporated into models of steady and possibly unsteady combustion. The kinetics can also be successfully used to understand the behavior of the energetic material in practical combustion problems.


1974 ◽  
Vol 249 (8) ◽  
pp. 2478-2482
Author(s):  
William D. Fordham ◽  
Charles Gilvarg

1980 ◽  
Vol 85 (2) ◽  
pp. 414-428 ◽  
Author(s):  
S D MacLean-Fletcher ◽  
T D Pollard

We have studied the kinetics of the gelation process that occurs upon warming cold extracts of Acanthamoeba using a low-shear falling ball assay. We find that the reaction has at least two steps, requires 0.5 mM ATP and 1.5 mM MgCl2, and is inhibited by micromolar Ca++. The optimum pH is 7.0 and temperature, 25 degrees-30 degrees C. The rate of the reaction is increased by cold preincubation with both MgCl2 and ATP. Nonhydrolyzable analogues of ATP will not substitute for ATP either in this "potentiation reaction" or in the gelation process. Either of two purified or any one of four partially purified Acanthamoeba proteins will cross-link purified actin to form a gel, but none can account for the dependence of the reaction in the crude extract on Mg-ATP or its regulation by Ca++. This suggests that the extract contains, in addition to actin-cross-linking proteins, factors dependent on Mg-ATP and Ca++ that regulate the gelation process.


2018 ◽  
Vol 7 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Norbert Halmen ◽  
Christoph Kugler ◽  
Eduard Kraus ◽  
Benjamin Baudrit ◽  
Thomas Hochrein ◽  
...  

Abstract. The degree of cross-linking and curing is one of the most important values concerning the quality of cross-linked polyethylene (PE-X) and the functionality of adhesives and resin-based components. Up to now, the measurement of this property has mostly been time-consuming and usually destructive. Within the shown work the feasibility of single-sided nuclear magnetic resonance (NMR) for the non-destructive determination of the degree of cross-linking and curing as process monitoring was investigated. First results indicate the possibility of distinguishing between PE-X samples with different degrees of cross-linking. The homogeneity of the samples and the curing kinetics of adhesives can also be monitored. The measurements show good agreement with reference tests (wet chemical analysis, differential scanning calorimetry, dielectric analysis). Furthermore, the influence of sample temperature on the characteristic relaxation times can be observed.


2017 ◽  
Vol 23 (4) ◽  
pp. 495-506 ◽  
Author(s):  
Larissa Falleiros ◽  
Bruna Cabral ◽  
Janaína Fischer ◽  
Carla Guidini ◽  
Vicelma Cardoso ◽  
...  

The immobilization and stabilization of Aspergillus oryzae ?-galactosidase on Duolite??A568 was achieved using a combination of physical adsorption, incubation step in buffer at pH 9.0 and cross-linking with glutaraldehyde and in this sequence promoted a 44% increase in enzymatic activity as compared with the biocatalyst obtained after a two-step immobilization process (adsorption and cross-linking). The stability of the biocatalyst obtained by three-step immobilization process (adsorption, incubation in buffer at pH 9.0 and cross-linking) was higher than that obtained by two-steps (adsorption and cross-linking) and for free enzyme in relation to pH, storage and reusability. The immobilized biocatalyst was characterized with respect to thermal stability in the range 55-65 ?C. The kinetics of thermal deactivation was well described by the first-order model, which resulted in the immobilized biocatalyst activation energy of thermal deactivation of 71.03 kcal/mol and 5.48 h half-life at 55.0 ?C.


1997 ◽  
Vol 13 (09) ◽  
pp. 848-852
Author(s):  
Chen Tong-Hui ◽  
◽  
Bai Yao-Wen ◽  
Sun Ren-Hui

Sign in / Sign up

Export Citation Format

Share Document