13C NMR study on structure, composition and curing behavior of phenol–urea–formaldehyde resole resins

Gong, He; Yan, Ning

doi:10.1016/j.polymer.2004.08.019

Cited by 58 publications

(61 citation statements)

References 24 publications

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“…The 13 C NMR spectra are shown in Figure 4, and their corresponding assignments of groups' signals are shown in Figure 5 [12,[18][19][20]. The chemical shift of 150.0-158.0 ppm was assigned to phenoxy carbons (C1-OH), which was used as an integral standard and analytical standpoint.…”

Section: Chemical Structure Analysismentioning

confidence: 99%

“…The presence of two ortho positions and one para position in an aromatic ring generally could lead to a PF resin containing mostly ortho hydroxymethyl groups [2]. However, in the process of PF resin synthesis, some catalysts could make more formaldehyde or methylol toward phenol ortho positions to increase the ratio of ortho/para substituted positions [12], leading to more reactive functional groups or more unreacted para positions at the curing stage, which may shorten the curing time and increase the cross-linking degree of cured PF resin.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins

Zhao

Zhang

et al. 2016

Polymers

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Phenol-formaldehyde (PF) resin is a high performance adhesive, but has not been widely developed due to its slow curing rate and high curing temperature. To accelerate the curing rate and to lower the curing temperature of PF resin, four types of metal-mediated catalysts were employed in the synthesis of PF resin; namely, barium hydroxide (Ba(OH) 2 ), sodium carbonate (Na 2 CO 3 ), lithium hydroxide (LiOH), and zinc acetate ((CH 3 COO) 2 Zn). The cure-acceleration effects of these catalysts on the properties of PF resins were measured, and the chemical structures of the PF resins accelerated with the catalysts were investigated by using Fourier transform infrared (FT-IR) spectroscopy and quantitative liquid carbon-13 nuclear magnetic resonance ( 13 C NMR). The results showed that the accelerated efficiency of these catalysts to PF resin could be ordered in the following sequence: Na 2 CO 3 > (CH 3 COO) 2 Zn > Ba(OH) 2 > LiOH. The catalysts (CH 3 COO) 2 Zn and Na 2 CO 3 increased the reaction activity of the phenol ortho position and the condensation reaction of ortho methylol. The accelerating mechanism of (CH 3 COO) 2 Zn on PF resin is probably different from that of Na 2 CO 3 , which can be confirmed by the differences in the differential thermogravimetric (DTG) curve and thermogravimetric (TG) data. Compared to the Na 2 CO 3 -accelerated PF resin, the (CH 3 COO) 2 Zn-accelerated PF resin showed different peaks in the DTG curve and higher weight residues. In the synthesis process, the catalyst (CH 3 COO) 2 Zn may form chelating compounds (containing a metal-ligand bond), which can promote the linkage of formaldehyde to the phenolic hydroxyl ortho position.

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Section: Chemical Structure Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins

Zhao

Zhang

et al. 2016

Polymers

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“…As the U-F weight ratio decreases, the surface of microcapsule gradually gets rough. In general, when the weight ratio of U-F is lower, the content of free-formaldehyde is higher, although the network density of PUF decreases, the condensation rate of U and F increases [35,36], which results in the quick deposition of PUF nanoparticle on the surface of microcapsule, forming rougher and more porous outer layer of the PUF shell. Because the completion of condensation reaction for the higher U-F weight ratio resins needs longer time compared with the lower U-F weight ratio resins, the completion of microencapsulating core with the higher U-F weight ratio resins also needs more time.…”

Section: Effects Of Different Polar Pre-polymermentioning

confidence: 99%

Preparation and characterization of poly(urea-formaldehyde) microcapsules filled with epoxy resins

Yuan

Liang

Xie

et al. 2006

Polymer

339

188

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“…13 C NMR has been used extensively to characterize phenolic resins. The chemical shifts of typical phenolic resins and some reaction intermediates are provided in Table 1, which are based on some former literature [23][24][25]. The 13 C NMR spectra of PTBP-FR are shown in Fig.…”

Section: Structure Of Ptbp-frmentioning

confidence: 99%