Study of the reaction rates and structures of a phenol-formaldehyde resol resin by carbon-13 NMR and gel permeation chromatography

1990 ◽  
Vol 29 (10) ◽  
pp. 2032-2037 ◽  
Author(s):  
Moon G. Kim ◽  
Larry W. Amos ◽  
Edwin E. Barnes
Keyword(s):  
Phenol Formaldehyde ◽  
Gel Permeation Chromatography ◽  
Reaction Rates ◽  
Gel Permeation ◽  
Resol Resin

Analysis of phenol-formaldehyde resols by gel permeation chromatography

1972 ◽  
Vol 16 (7) ◽  
pp. 1585-1602 ◽  
Author(s):  
M. Duval ◽  
B. Bloch ◽  
S. Kohn
Keyword(s):  
Phenol Formaldehyde ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

scholarly journals Improving the Reactivity of Sugarcane Bagasse Kraft Lignin by a Combination of Fractionation and Phenolation for Phenol–Formaldehyde Adhesive Applications

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1825 ◽  
Author(s):  
Bin Luo ◽  
Zhuan Jia ◽  
Hongrui Jiang ◽  
Shuangfei Wang ◽  
Douyong Min
Keyword(s):  
Sugarcane Bagasse ◽  
Active Sites ◽  
Phenol Formaldehyde ◽  
Gel Permeation Chromatography ◽  
Kraft Lignin ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Formaldehyde Content ◽  
Gel Permeation ◽  
Application Requirements

The low reactivity of lignin hinders its application as a phenol substitute in phenol–formaldehyde (PF) resin. Therefore, the combination of fractionation and phenolation was adopted to enhance the reactivity of lignin for preparing a phenol–formaldehyde resin adhesive. Sugarcane bagasse kraft lignin and its fractions were employed to replace 40 wt% of phenol to prepare a PF adhesive. The fractionation increased the reactivity of lignin, however the as-prepared lignin-based PF (LPF) hardly met its application requirements as an adhesive. Therefore, the phenolation of lignin under an acidic condition was adopted to further improve its reactivity. The phenolated lignin was characterized by FTIR, gel permeation chromatography, and NMR, indicating its active sites increased while its molecular weight decreased. The phenolated lignin was used to replace 40 wt% of phenol to prepare a PF adhesive (PLPF) which was further employed to prepare plywood. The results indicated that the combination of fractionation and phenolation effectively enhanced the reactivity of lignin, and eventually improved the properties of the PLPF and its corresponding plywood. The free formaldehyde content of PLPF decreased to 0.16%. The wet bonding strength of the as-prepared plywood increased to 1.36 MPa, while the emission of formaldehyde decreased to 0.31 mL/L.

Fractionation of phenol-formaldehyde reaction mixtures with gel permeation chromatography

1968 ◽  
Vol 40 (3) ◽  
pp. 547-551 ◽  
Author(s):  
Edwin J. Quinn ◽  
Hans W. Osterhoudt ◽  
John S. Heckles ◽  
D. C. Ziegler
Keyword(s):  
Phenol Formaldehyde ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

Study of the molecular mass characteristics of phenol formaldehyde resins by gel-permeation chromatography

1986 ◽  
Vol 28 (10) ◽  
pp. 2322-2326
Author(s):  
I.A. Vakhtina ◽  
G.V. Shirokova ◽  
Ch.M. Yemelina ◽  
O.G. Tarakanov
Keyword(s):  
Molecular Mass ◽  
Phenol Formaldehyde ◽  
Gel Permeation Chromatography ◽  
Gel Permeation

Aggregated, Conformationally Changed Fibrinogen Exposes the Stimulating Sites for t-PA-Catalysed Plasminogen Activation

1996 ◽  
Vol 75 (02) ◽  
pp. 326-331 ◽  
Author(s):  
Unni Haddeland ◽  
Knut Sletten ◽  
Anne Bennick ◽  
Willem Nieuwenhuizen ◽  
Frank Brosstad
Keyword(s):  
Conformational Changes ◽  
Gel Permeation Chromatography ◽  
Tissue Type ◽  
Plasminogen Activation ◽  
Chromogenic Substrate ◽  
Type Plasminogen Activator ◽  
Gel Permeation ◽  
Self Association ◽  
Fibrin Monomers ◽  
Stimulation Of

SummaryThe present paper shows that conformationally changed fibrinogen can expose the sites Aα-(148-160) and γ-(312-324) involved in stimulation of the tissue-type plasminogen activator (t-PA)-catalysed plasminogen activation. The exposure of the stimulating sites was determined by ELISA using mABs directed to these sites, and was shown to coincide with stimulation of t-PA-catalysed plasminogen activation as assessed in an assay using a chromogenic substrate for plasmin. Gel permeation chromatography of fibrinogen conformationally changed by heat (46.5° C for 25 min) demonstrated the presence of both aggregated and monomeric fibrinogen. The aggregated fibrinogen, but not the monomeric fibrinogen, had exposed the epitopes Aα-(148-160) and γ-(312-324) involved in t-PA-stimulation. Fibrinogen subjected to heat in the presence of 3 mM of the tetrapeptide GPRP neither aggregates nor exposes the rate-enhancing sites. Thus, aggregation and exposure of t-PA-stimulating sites in fibrinogen seem to be related phenomena, and it is tempting to believe that the exposure of stimulating sites is a consequence of the conformational changes that occur during aggregation, or self-association. Fibrin monomers kept in a monomeric state by a final GPRP concentration of 3 mM do not expose the epitopes Aα-(148-160) and γ-(312-324) involved in t-PA-stimulation, whereas dilution of GPRP to a concentration that is no longer anti-polymerizing, results in exposure of these sites. Consequently, the exposure of t-PA-stimulating sites in fibrin as well is due to the conformational changes that occur during selfassociation.

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