scholarly journals Kinetic Study of Curing Phenol-Formaldehyde/Tannin-Formaldehyde Composite Resins

2015 ◽  
Vol 06 (10) ◽  
pp. 503-513 ◽  
Author(s):  
Hussein Ali Shnawa ◽  
Ibraheem Kadum Ibraheem ◽  
Ashwaq Aboud Shenta
2013 ◽  
Vol 9 (2) ◽  
pp. 1921-1932
Author(s):  
R. K. Seenivasan ◽  
D. Ragavan ◽  
A. Girija ◽  
R. Muthuramalingam

Phenol – Formaldehyde Resin (PFR) is blended with Sulphonated Phyllanthus emblica, Linn., Carbon (SPEC) in various proportions by weight percentage (0-50%w/w). A few composite cation-exchangers were prepared by varying the amount of SPEC (a source of cheap and renevable plant material) in the blends from 10 to 50% (w/w). Reaction conditions for the preparation of blends were optimised. IR spectra, TGA traces, and SEM photos were taken for the characterization of  resins. Physico-chemical, properties of the composite resins have been determined. The composites are insoluble in various solvents and reagents and stable towards heat.   Cation exchange capacity (CEC) of the composite resins, decreased with the increasing percentage of SPEC in the blend. Thermodynamic equilibrium constants (lnK) are calculated for H+ - Zn2+ exchanges on the resins having a different amount of SPEC. Thermodynamic parameters are also calculated and suitable explanations are given. The composites up to 20% (w/w) blending retains all the essential properties of the original PFR, since the Phyllanthus emblica, Linn., is the low cost, freely available plant material. Therefore, the composites could be used as low cost ion-exchangers, when SPEC partly replaces the original PFR up to 20% (w/w) blending without affecting the properties of PFR.


2008 ◽  
Vol 105 (12) ◽  
pp. 601-608
Author(s):  
Seung Min Han ◽  
Dong Joon Min ◽  
Joo Hyun Park ◽  
Jung Ho Park ◽  
Jong Min Park
Keyword(s):  

1983 ◽  
Vol 49 (03) ◽  
pp. 199-203 ◽  
Author(s):  
V M Yomtova ◽  
N A Stambolieva ◽  
B M Blagoev

SummaryIt was found that the effect of heparin on the amidase activity of urokinase (E C 3.4.21.31), plasmin (E C 3.4.21.7) and trypsin (E C 3.4.21.4) depended on the substrate used. No effect of heparin on the amidase activity of urokinase and trypsin was observed when Pyro Glu-Gly-Arg-p-nitroanilide (S-2444) and α-N-acetyl-L-lysine-p-nitroanilide (ALNA) were used as substrates. Heparin acted as a uncompetitive inhibitor of trypsin (Ki = 1.2×10-6 M), plasmin (Ki = 4.9×10-6 M) and urokinase (Ki = l.0×10-7 M) when Bz-Phe-Val-Arg-p-nitroanilide (S-2160), H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and plasminogen, respectively, were used as substrates. These results, as well as the data obtained by studying the effect of the simultaneous presence of heparin and competitive inhibitors suggest that although heparin is not bound at the active center of these enzymes, it may influence the effectivity of catalysis.


1981 ◽  
Vol 31 (1) ◽  
pp. 388-394 ◽  
Author(s):  
Mahmoud El-Sawi ◽  
Antonio Iannibello ◽  
Fernando Morelli ◽  
Ganfranco Gatalano ◽  
Francesco Intrieri ◽  
...  
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document