Structural features of resorcinol–formaldehyde resin chars and interfacial behavior of water co-adsorbed with low-molecular weight organics

Abstract The application of phenol-formaldehyde resins as crosslinking agents is increasing in importance due to the good high temperature properties of the corresponding vulcanizate and the use in thermoplastic vulcanizates. With respect to the chemistry of phenol-formaldehyde cure (reaction mechanism and structure of crosslink) there are still problems that have to be resolved. The reaction products of the phenol-formaldehyde resin curing of EPDM, contain 2-ethylidene norbornene (ENB) as the third monomer, have been studied. Since such an investigation is rather difficult to perform for the polymer system, a low molecular weight model for EPDM was used: 2-ethylidene norbornane (ENBH). Reaction of ENBH and a resole results in scission of the dimethylene ether bridges, i.e. in degradation of the resole into mono-, bis- and terisooctylphenol units. These are consequently converted into products, consisting of two ENBH molecules linked by mono-, bis- and terisooctylphenol units. The solid resole seems to be a technological solution for storing phenol in combination with formaldehyde. These results support the use of 2-hydroxymethylphenol (HMP) as a low molecular weight model for the resole. At low temperatures and/or short reaction times HMP oligomers (= resoles) and HMP oligomers linked to one ENBH molecule are formed, which are converted into ENBH/HMP (1:1) condensation products. The reaction products of ENBH with both the resole and HMP are shown to contain methylene linked structures, as demonstrated by the formation of monisooctylphenol crosslinks and the presence of residual unsaturation and hydroxyl groups, besides chroman linked structures. This is the first experimental evidence that during phenol-formaldehyde resin cure of rubber, formation of methylene bridges occurs.

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New Application of Proton Nuclear Spin Relaxation Unraveling the Intermolecular Structural Features of Low-Molecular-Weight Organogel Fibers

Journal of the American Chemical Society ◽

10.1021/ja303679z ◽

2012 ◽

Vol 134 (25) ◽

pp. 10621-10627 ◽

Cited By ~ 18

Author(s):

Sabine Bouguet-Bonnet ◽

Mehdi Yemloul ◽

Daniel Canet

Keyword(s):

Molecular Weight ◽

Spin Relaxation ◽

Nuclear Spin ◽

Structural Features ◽

Nuclear Spin Relaxation ◽

Low Molecular Weight

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Structural features of low-molecular-weight heparins affecting their affinity to antithrombin

Thrombosis and Haemostasis ◽

10.1160/th09-02-0081 ◽

2009 ◽

Vol 102 (11) ◽

pp. 865-873 ◽

Cited By ~ 61

Author(s):

Antonella Bisio ◽

Davide Vecchietti ◽

Laura Citterio ◽

Marco Guerrini ◽

Rahul Raman ◽

...

Keyword(s):

Molecular Weight ◽

Nmr Spectra ◽

Biological Activities ◽

Anticoagulant Activity ◽

2D Nmr ◽

Structural Features ◽

Size Exclusion ◽

Low Molecular Weight ◽

Low Molecular Weight Heparins ◽

2D Nmr Spectra

SummaryAs part of a more extensive investigation on structural features of different low-molecular-weight heparins (LMWHs) that can affect their biological activities, Enoxaparin,Tinzaparin and Dalteparin were characterised with regards to the distribution of different chain length oligosaccharides as determined by size-exclusion (SE) chromatography, as well as their structure as defined by 2D-NMR spectra (HSQC). The three LMWHs were also fractionated into high affinity (HA) and no affinity (NA) pools with regards to their ability to bind antithrombin (AT).The HA fractions were further subfractionated and characterised. For the parent LMWHs and selected fractions,molecular weight parameters were measured using a SE chromatographic system with a triple detector (TDA) to obtain absolute molecular weights. The SE chromatograms clearly indicate that Enoxaparin is consistently richer in shorter oligosaccharides than Tinzaparin and Dalteparin. Besides providing the content of terminal groups and individual glucosamine and uronic acid residues with different sulfate substituents, the HSQC-NMR spectra permitted us to evaluate and correlate the content of the pentasaccharide, AT-binding sequence A-G-A*-I-A (AT-bs) through quantification of signals of the disaccharide sequence G-A*.Whereas the percent content of HA species is approximately the same for the three LMWHs, substantial differences were observed for the chain distribution of AT-bs as a function of length, with the AT-bs being preferentially contained in the longest chains of each LMWH. The above information will be useful in establishing structure-activity relationships currently under way. This study is therefore critical for establishing correlations between structural features of LMWHs and their AT-mediated anticoagulant activity.

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A comparison between the properties of low and medium molecular weight phenol formaldehyde resin-treated laminated compreg oil palm wood

International Forestry Review ◽

10.1505/146554817828562305 ◽

2017 ◽

Vol 19 (3) ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

G. Aizat ◽

A. Zaidon ◽

S. H. Lee ◽

S. B. Edi ◽

B. Paiman

Keyword(s):

Molecular Weight ◽

Oil Palm ◽

Phenolic Resin ◽

Phenol Formaldehyde ◽

Phenol Formaldehyde Resin ◽

Formaldehyde Resin ◽

Low Molecular Weight ◽

Hot Press ◽

Plastic Bag ◽

Better Than

In order to improve the inherently poor properties of oil palm wood (OPW), this study examines the effects of resin molecular weight, diffusion time and compression ratio on the properties of laminated compreg OPW. Treating solutions used were medium molecular weight phenol formaldehyde (MmwPF) and low molecular weight phenol formaldehyde (LmwPF). OPW strips were soaked in the treating solutions for 24 h before wrapping in a plastic bag and leaving them for diffusion for 2, 4 and 6 days, respectively. Then, three-layer laminated compreg OPW were fabricated and compressed in hot press at 150°C for 20 minutes to achieve compression ratios of 55%, 70% and 80%. Results indicated that dimensional stability and mechanical properties of the phenolic resin treated laminated compreg OPW were significantly better than the untreated laminates. MmwPF-treated laminates exhibited inferior properties in comparison to that of LmwPF-treated laminates. Nevertheless, MmwPF-treated laminated compreg OPW emitted significantly lesser formaldehyde.

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Characterization of Low Mololecular Weight Factor VIII.

10.1055/s-0039-1687038 ◽

1979 ◽

Author(s):

G. Rock ◽

D. Palmer ◽

E. Kang ◽

G. Jamieson ◽

W. Cruickshank

Keyword(s):

Molecular Weight ◽

Factor Viii ◽

Polyacrylamide Gel Electrophoresis ◽

Structural Features ◽

Protein Characterization ◽

Low Molecular Weight ◽

Weight Factor ◽

High Molecular Weight Complex ◽

Peptide Map ◽

Polyethylene Glycol Precipitation

The high molecular weight complex of Factor VIII was isolated from resolubilized cryoprecipitate by polyethylene glycol precipitation followed by chromatography on Bio Gel A15M. Upon rechromatography of this compound in buffer containing 1M NaCl and 1mM benzamidine the low molecular weight sub-unit possessing the procoagulant activity eluted at a volume of 2.3V. SDS polyacrylamide gel electrophoresis of this material in 5% acrylamide gave a single band whose Rf indicated a molecular weight of 150,000. The isoelectric point was determined to be 7.4. A peptide map of pepsin digested, I125 labelled material showed very few peptides which were radioactive and/or fluorescamine positive; as well, there was a relatively large amount of radioactive, non-fluorescamine positive material which was slow moving on pH 2.1 electrophoresis and immobile on chromatography. Amino acid analysis yielded data consistent with the presence of a small amount of protein. Carbohydrate analysis indicated a large amount of neutral hexoses, a very small amount of hexosamines and no detectable sialic acid. These results suggest that the structural features of low molecular weight Factor VIII may account for its anomalous behaviour in standard protein characterization procedures.

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