Controlled synthesis of high‐ortho‐substitution phenol–formaldehyde resins

Huang, Jianying; Xu, Miao‐Qing; Ge, Qiang; Lin, Min; Lin, Qiang; Chen, Yihong; Jiayan, Chu; Dai, Lizong; Yousi, Zou

doi:10.1002/app.21808

Cited by 40 publications

(40 citation statements)

References 13 publications

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“…2(a)], which was further confirmed by the appearance of a strong peak at 1.3 d. The terminal methyl group of the alkyl side chain was also seen, as there appeared a small peak at 0.8 d. The peak at 3.7 d indicated the presence of methylene protons of C 6 H 5 ACH 2 AC 6 H 5 for the bridge between the phenyl rings. [25][26][27] All these spectral data indicated that the condensation of methyolated cardanol was completed under the experimental conditions [see Fig. 2(b,c)] and was fully consistent with the proposed structure (Scheme 1) resulting from the reaction mechanism shown in our recent article 16 for the cardanol-based novolac resin prepared with a citric acid catalyst.…”

Section: Ftir Spectroscopic Analysis Of Cf 71 and Cf 72supporting

confidence: 80%

Synthesis and properties of cardanol‐based epoxidized novolac resins modified with carboxyl‐terminated butadiene–acrylonitrile copolymer

Yadav

Srivastava

2009

J of Applied Polymer Sci

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Cardanol-based, novolac-type phenolic resins were synthesized with a cardanol-to-formaldehyde molar ratio of 1 : 0.7 with different dicarboxylic acid catalysts, including oxalic and succinic acids. These novolac resins were epoxidized with a molar excess of epichlorohydrin at 120 C in a basic medium. The epoxidized novolac resins were separately blended with different weight ratios of carboxyl-terminated butadiene-acrylonitrile copolymer (CTBN) ranging between 0 and 20 wt % with an interval of 5 wt %. All of the blends were cured at 120 C with a stoichiometric amount of polyamine. The formation of various products during the synthesis of the cardanol-based novolac resin and epoxidized novolac resin and the blending of the epoxidized novolac resin with CTBN was studied by Fourier transform infrared spectroscopy analysis. Furthermore, the products were also confirmed by proton nuclear magnetic resonance and matrix-assisted laser desorption/ionization time-offlight mass spectroscopy analysis. The molecular weights of the prepared novolacs and their epoxidized novolac resins were determined by gel permeation chromatography analysis. The blend samples, in both cases, with 15 wt % CTBN concentrations showed the minimum cure times. These blend samples were also the most thermally stable systems. The blend morphology, studied by scanning electron microscopy analysis, was, finally, correlated with the structural and property changes in the blends.

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Section: Ftir Spectroscopic Analysis Of Cf 71 and Cf 72supporting

confidence: 80%

Synthesis and properties of cardanol‐based epoxidized novolac resins modified with carboxyl‐terminated butadiene–acrylonitrile copolymer

Yadav

Srivastava

2009

J of Applied Polymer Sci

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“…The 13 C-NMR spectra of all PUF resins are presented in Figure 2. The assignments of the most characteristic chemical shifts are listed in Table 2 based on the former studies and literatures [7,8,[14][15][16][17][18][19]. As can be seen, the spectral features of all PUF resin are qualitatively similar to each other.…”

Section: Chemical Structurementioning

confidence: 57%

“…The reasons were that there were twice as many ortho position of phenolic units available than para position; para-methylol groups reacted more easily with urea units to form methylene bridges, therefore, leading to the para/ortho ratio of methylols less than 1. A bivalent metal ion such as Mg 2+ was reported to be beneficial for increasing the proportion of high-ortho linkage in PF resins due to its ortho-directing effect [14]. For our preparation methods of PUF resin, only co-condensed methylene between phenolic components and urea units were formed and none of self-condensation methylene of phenolic rings was present in all PUF resins.…”

Section: Synthesismentioning

confidence: 99%

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Synthesis and Structure Characterization of Phenol-Urea-Formaldehyde Resins in the Presence of Magnesium Oxide as Catalyst

Fan

Qin

et al. 2014

Polymers

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Abstract:The objective of this research was to provide a useful approach of polymer synthesis for accelerating the fast cure of phenol-urea-formaldehyde (PUF) resin as wood adhesive by optimizing its structure and composition. The PUF resins containing high contents of very reactive groups such as para-methylol groups were synthesized by reacting methylolurea, phenol, and formaldehyde in the presence of magnesium oxide (MgO) as catalyst. The effects of synthesis parameters including F/(P + U), OH/P, and MgO/P mole ratios on the structure, composition, curing characteristics, and their relationships of PUF resins were investigated. The results indicated that MgO seemed to be an efficacious catalyst for PUF resin synthesis and promote its faster cure. The increase in the F/(P + U) mole ratio or/and OH/P mole ratio appeared to be beneficial for the formation of para-methylol groups and cocondensed methylene linkages between phenolic methylol groups and urea units, and for the removal of unreacted urea. In case of Catalyst/P mole ratio, an appropriate dosage of added metal-ion was very important for synthesizing the high-content reactive groups of PUF resins, otherwise leading to the reverse effects.

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“…The terminal methyl group of the alkyl side chain may also be seen as there appeared a small peak at 0.8 d. The peak at 3.7 d indicated the presence of methylene protons of C 6 H 5 ACH 2 AC 6 H 5 for the bridge between the phenyl rings. 30 All these spectral data indicated that the condensation of methylolated cardanol has been completed under experimental conditions and was fully consisted with the proposed mechanism.…”

Section: Resultsmentioning

confidence: 91%

Studies on synthesis of modified epoxidized novolac resin from renewable resource material for application in surface coating

Yadav

Srivastava

2009

J of Applied Polymer Sci

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Five blend samples of cardanol-based epoxidized novolac resin containing varying concentrations of carboxyl-terminated poly(butadiene-co-acrylonitrile) (CTBN) ranging between 0 and 25 wt % with an interval of 5 wt % were prepared. The epoxidized novolac resin (ECF) was synthesized from the epoxidation of cardanol-based novolac-type phenolic resin (CF) with molar excess of epichlorohydrin (i.e., about 10 mol at 120 C in basic medium). The CF resin was synthesized with a molar ratio of 1 : 0.5 of CF using dicarboxylic acid catalyst such as succinic acid at 120 C for 5 h. The pure epoxy and its blend were cured with stoichiometric amounts of polyamine curing agent. The formation of various products during the synthesis of cardanol-based novolac resin, epoxidized novolac resin, and blending of epoxidized novolac resin with CTBN have been studied by Fourier transform infrared (FTIR) spectroscopic analysis. Further, a reaction mechanism for the step-growth reaction was proposed on the basis of the results of FTIR analysis. Also, the structures of CF and ECF were proposed on the basis of the results of nuclear magnetic resonance and MALDI-TOF mass spectroscopic analysis along with gel permeation chromatographic (GPC) analysis. GPC analysis resulted in M n of 670 gmol À1 . The blend sample having 15 wt % CTBN concentration showed minimum cure time, whereas the presence of CTBN in blend systems showed marginal change in the values of DH. A clear-cut two-step mass loss in dynamic thermogravimetric trace of unmodified and CTBN-modified systems was observed. Thermal stability of the blend sample containing 15 wt % CTBN into the pure epoxy resin was the highest among all other prepared systems.

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Controlled synthesis of high‐ortho‐substitution phenol–formaldehyde resins

Cited by 40 publications

References 13 publications

Synthesis and properties of cardanol‐based epoxidized novolac resins modified with carboxyl‐terminated butadiene–acrylonitrile copolymer

Synthesis and properties of cardanol‐based epoxidized novolac resins modified with carboxyl‐terminated butadiene–acrylonitrile copolymer

Synthesis and Structure Characterization of Phenol-Urea-Formaldehyde Resins in the Presence of Magnesium Oxide as Catalyst

Studies on synthesis of modified epoxidized novolac resin from renewable resource material for application in surface coating

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