scholarly journals SELECTED PROPERTIES OF COMPREGNATED WOOD USING LOW MOLECULAR WEIGHT PHENOL FORMALDEHYDE AND SUCCINIC ANHYDRIDE

Wood Research ◽  
2021 ◽  
Vol 66 (5) ◽  
pp. 762-776
Author(s):  
SARAH AUGUSTINA ◽  
IMAM WAHYUDI ◽  
WAYAN DARMAWAN ◽  
JAMALUDIN MALIK ◽  
NAOKI OKANO ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Specific Gravity ◽  
Dimensional Stability ◽  
Succinic Anhydride ◽  
Phenol Formaldehyde ◽  
Densified Wood ◽  
Low Molecular Weight ◽  
Spring Back ◽  
Initial Thickness ◽  
Better Than

The aim of this study was to investigate the effect of impregnating materials (low molecular weight phenol formaldehyde or LmwPF and succinic anhydride or SA), their concentrations (5and 10%), and compression ratios (20 and 40% from initial thickness)on improvement of specific gravity (SG) and dimensional stability on nyatoh, sepetir, and pisang putih wood; and then compared them to control and densified wood. The results showed that SG and dimensional stability of compregnated wood were affected by all parameters studied. Higher compression ratio and concentration will result in a greater improvement.In general, SG and dimensional stability of compregnated wood were better than the control.SG of LmwPF-and SA-compregnated wood increased by 10.69‒22.31% and 6.96‒23.09%, respectively. Utilization of LmwPF and SA has significantly reduced the spring-back, butthe latter is better. Thecompression-set recovery after compregnation was 18.34‒33.99%, while after densification was 47.86‒71.49%.

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

2017 ◽  
Vol 19 (3) ◽  
pp. 1-11 ◽  
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.

The Chemistry of Phenol-Formaldehyde Resin Vulcanization of EPDM: Part I. Evidence for Methylene Crosslinks

1995 ◽  
Vol 68 (5) ◽  
pp. 717-727 ◽  
Author(s):  
Martin van Duin ◽  
Aniko Souphanthong
Keyword(s):  
Molecular Weight ◽  
Phenol Formaldehyde ◽  
Polymer System ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Low Molecular Weight ◽  
Hydroxyl Groups ◽  
Reaction Products ◽  
Cure Reaction ◽  
Weight Model

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.

Effect of Various Curing Agents On the Chemical Stability of Epoxy Resins

CORROSION ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 11t-20t ◽  
Author(s):  
RONALD L. DeHOFF
Keyword(s):  
Molecular Weight ◽  
Chemical Stability ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Curing Agent ◽  
Corrosion Prevention ◽  
Curing Agents ◽  
Outdoor Weathering ◽  
Better Than

Abstract The epoxy resins most widely used in corrosion prevention are liquids of low molecular weight which can be converted to hard, tough, chemically resistant polymers by the use of various curing agents. Unlike other thermosetting resins such as polyesters, the curing agents may produce chemical linkages in the final polymers that differ from those present in the uncured form. Hence, the properties of cured epoxy resins are likely dependent upon, and may even reflect the properties of the curing agent used. Some seven different epoxy resin systems were exposed to various chemical environments and evaluatd for changes in dimensional stability and flexural strengths over a six month period. From the data presented herein, only limited conclusions may be drawn. Heat cured systems fare better than room temperature cured systems in every case. Anhydride cured epoxy resins show greater resistance to outdoor weathering than amine cured systems. 5.4.5, 6.6.8

Comparative Study on the Anticoagulant Effects of Low Molecular Weight Heparins as Measured by Whole Blood Act, Anti-Xa and a Newly Developed Prothrombinase Induced Clotting Time (PiCT) Assay.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4148-4148
Author(s):  
D. Hoppensteadt ◽  
M. Tobu ◽  
R. Wahi ◽  
O. Iqbal ◽  
J. M. Walenga ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Whole Blood ◽  
Low Molecular Weight ◽  
Plasma Samples ◽  
Clotting Time ◽  
Low Molecular Weight Heparins ◽  
Blood Samples ◽  
Good Relationship ◽  
Surgical Conditions ◽  
Better Than

Abstract Low Molecular Weight Heparins (LMWHs) are currently developed for anticoagulation in various intravenous indications such as DVT treatment and percutaneous interventions (PCI). Traditionally, these drugs are administered in anti-Xa units. The purpose of this study was to compare the relative levels of anticoagulation produced by different LMWHs in whole blood ACT (Hemochron), an amidolytic anti-Xa method and a plasma-based global anticoagulant assay, the PiCT test (Pentapharm, Basel, Switzerland). Various LMWHs such as dalteparin, enoxaparin, reviparin and a synthetic pentasaccharide were supplemented to freshly drawn native blood samples to simulate patient samples containing 1 U/ml anti-Xa levels. Three generic versions of enoxaparin were also included in this study. In addition to the ACT measurement in whole blood, citrated plasma samples were also tested for APTT, Heptest, PiCT, amidolytic anti-Xa and IIa activities, and protease generation assays. All agents produced assay-based effects on different tests, which were not proportional to the adjusted anti-Xa activity. Correlation of the ACT data resulted in a good relationship with PiCT for the commercially available branded products(r2=0.97). ACT and Heptest (r2=0.51), ACT and anti-Xa (r2<0.3), ACT and anti-IIa (r2= 0.93). The correlation of PiCT and Heptest was (r2=0.73) better than ACT and Heptest. However, the generic versions of enoxaparin did not provide similar results. PiCT and Heptest also gave the good correlation. These results clearly suggest that for the global anticoagulant actions of LMWHs, anti-Xa measurements are of limited value and should not be used to asses the anticoagulant efficacy of LMWHs in PCI and other surgical conditions. These differences may be more obvious in the generic versions of LMWHs, which are apparently produced using pharmacopeial specifications. Thus, it is important to include a clot-based method in the cross referencing and standardization of LMWHs.

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