Investigation of urea–formaldehyde polymer cure by infrared

Myers, George E.

doi:10.1002/app.1981.070260301

Cited by 54 publications

(51 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, this result was also compatible with the occurrence of the 1320 cm Ϫ1 band assigned to ACON or -CHON structure as reported. 25 The spectra of both resins from alkaline and strong-acid reaction conditions showed strong bands at 1032 and 1024 cm Ϫ1 , respectively. The band from 1030 to 1050 cm Ϫ1 could be assigned to CON stretching from CON or CON 2 , of amides in the resins.…”

Section: Resultsmentioning

confidence: 98%

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state ¹³C CP/MAS NMR spectroscopy

Park¹,

Kim²,

Singh³

et al. 2003

J of Applied Polymer Sci

View full text Add to dashboard Cite

This study was conducted to investigate the effects of reaction pH condition and hardener type on the reactivity, chemical structure, and molecular mobility of urea-formaldehyde (UF) resins. Three different reaction pH conditions, such as alkaline (7.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins, which were cured by adding four different hardeners (ammonium chloride, ammonium sulfate, ammonium citrate, and zinc nitrate) to measure gel time as the reactivity. FTIR and 13 C-NMR spectroscopies were used to study the chemical structure of the resin prepared under three different reaction pH conditions. The gel time of UF resins decreased with an increase in the amount of ammonium chloride, ammonium sulfate, and ammonium citrate added in the resins, whereas the gel time increased when zinc nitrate was added. Both FTIR and 13 C-NMR spectroscopies showed that the strong reaction pH condition produced uronic structures in UF resin, whereas both alkaline and weak-acid conditions produced quite similar chemical species in the resins. The proton rotating-frame spin-lattice relaxation time (T 1H ) decreased with a decrease in the reaction pH of UF resin. This result indicates that the molecular mobility of UF resin increases with a decrease in the reaction pH used during its synthesis.

show abstract

Section: Resultsmentioning

confidence: 98%

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state ¹³C CP/MAS NMR spectroscopy

Park¹,

Kim²,

Singh³

et al. 2003

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Figure 7 shows the FTIR spectra of the cured UF0 and MUF resins. In addition, the assignments of absorption bands are tabulated in Table 4 according to the literature (Padgett and Hamner 1958;Myers 1981;Jada 1988;Socrates 1994). A distinct peak at 814 cm -1 was detected for each MUF resin, which was attributed to the stretching of the triazine ring structure of melamine.…”

Section: Structure Of Cured Muf Resinsmentioning

confidence: 99%

Effects of Melamine Addition Stage on the Performance and Curing Behavior of Melamine-Urea-Formaldehyde (MUF) Resin

Zhang¹,

Wang²,

Zhang³

et al. 2013

BioResources

View full text Add to dashboard Cite

Three formaldehyde-based resins were prepared: urea-formaldehyde (UF) resin without melamine modifier (named UF0 resin) and melamineurea-formaldehyde (MUF) resins with melamine modifier added at two different synthesis stages (named MUF1 resin and MUF2 resin). The effects of the melamine addition stage on the performance and curing behavior of MUF resin were studied. Three-ply plywood bonded by these adhesives was manufactured, and its bond strength and formaldehyde emissions were measured. The curing behavior and functional groups of the resins were measured by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). Their activation energies were calculated using the Kissinger equation and the KissingerAkahira-Sunose (KAS) method. The results showed that melamine addition and the addition stage had significant influences on the characteristics of resins. The plywood bonded by MUF1 resin showed the highest bond strength and the lowest formaldehyde emissions. The activation energies of UF0 resin, MUF1 resin, and MUF2 resin were significantly different; the values were 99.44 kJ/mol, 105.75 kJ/mol, and 150.65 kJ/mol, respectively. According to the FT-IR spectra, the amount of methylene and methylene-ether bonds in cured MUF2 resin was the lowest, which meant that the cross-linking degree of MUF2 resin was the lowest.

show abstract

“…The polymerization conversion is determined by the change of the absorbed peak in FTIR characterization. 17,18 The conversion of the respective time is given by…”

Section: Up/pu Network Formationmentioning

confidence: 99%

Effect of reactive polyurethane on toughness of unsaturated polyester resin

Min

Hwang

Choi

et al. 2002

J of Applied Polymer Sci

View full text Add to dashboard Cite

Unsaturated polyester (UP) resin is one of the major thermosetting resins and is very useful as a matrix resin of composite material for its processibility. UP resin, however, has several shortcomings: it is weak in alkalis, volume shrinkage occurs during the crosslinking reaction of the oligomeric UP resin with a styrene monomer, and it is also brittle. The mechanical properties of UP resin can be enhanced by blending it with various materials. In this study, polyurethane (PU) was used as a modifier to improve the toughness of the UP resin. The effect of the polyol molecular weight as a PU soft segment and the PU contents on the toughness of PU-modified UP resins were studied. A UP/PU polymer network may occur through a reaction between an isocyanate group in the methyl diisocyanate (MDI) and a hydroxyl one in the UP molecules. The maximum toughness was observed at approximately 2 wt % of the PU content. These results can be rationalized by the incorporation of a rubbery PU segment into a brittle UP resin.

show abstract

Investigation of urea–formaldehyde polymer cure by infrared

Cited by 54 publications

References 26 publications

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state ¹³C CP/MAS NMR spectroscopy

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state ¹³C CP/MAS NMR spectroscopy

Effects of Melamine Addition Stage on the Performance and Curing Behavior of Melamine-Urea-Formaldehyde (MUF) Resin

Effect of reactive polyurethane on toughness of unsaturated polyester resin

Contact Info

Product

Resources

About

Investigation of urea–formaldehyde polymer cure by infrared

Cited by 54 publications

References 26 publications

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state 13C CP/MAS NMR spectroscopy

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state 13C CP/MAS NMR spectroscopy

Effects of Melamine Addition Stage on the Performance and Curing Behavior of Melamine-Urea-Formaldehyde (MUF) Resin

Effect of reactive polyurethane on toughness of unsaturated polyester resin

Contact Info

Product

Resources

About

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state ¹³C CP/MAS NMR spectroscopy

Reactivity, chemical structure, and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state ¹³C CP/MAS NMR spectroscopy