An investigation of the crosslinking of polyacrylamide with formaldehyde using <sup>13</sup>C nuclear magnetic resonance spectroscopy

Fong, Dodd W.; Kowalski, David J.

doi:10.1002/pola.1993.080310633

Cited by 14 publications

(11 citation statements)

References 3 publications

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“…The main reacting was the NH 2 groups of AM and the OH groups of NMA at pH < 2, and this result has already been reported by Fong and Kowalski 31. The maximum double‐bond content (1.82%) is obtained at hydrochloric acid 0.8 mL as shown in Figure 4.…”

Section: Resultssupporting

confidence: 81%

Chemical modification and synthesizing conditions of nanocomposite hydrogels with high mechanical strength crosslinked by hydrophilic reactive microgels

Qin

Fang

Feng

2011

J of Applied Polymer Sci

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Series of polyacrylamide hydrogels with high mechanical strength were synthesized using hydrophilic reactive microgels (HRM) with C¼ ¼C double bonds as crosslinkers. The hydrophilic microgels were prepared by inverse emulsion photopolymerization and then were chemical modified by N-methylolacrylamide (NMA) to obtain HRM. Chemical-modifying conditions affecting the HRM double bound content were investigated. The maximum double-bond content was 1.82% at the optimum conditions of NMA 8 g, hydrochloric acid 0.8 mL, reaction temperature 60 C, and time 4 h. The mechanical properties of the hydrogels were significantly enhanced by using HRM as crosslinkers instead of the conventional crosslinkers. These HRM hydrogels were studied by varying such parameters as HRM content, monomer concentration, HRM double-bond content, and the initiator dosage.

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Section: Resultssupporting

confidence: 81%

Chemical modification and synthesizing conditions of nanocomposite hydrogels with high mechanical strength crosslinked by hydrophilic reactive microgels

Qin

Fang

Feng

2011

J of Applied Polymer Sci

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“…Similar to polyacrylamide (PAM), the Mannich reaction takes place at the AM unit of P(DMDAAC‐ co ‐AM). Thus, the aminomethylation reaction conditions of PAM during the Mannich reaction can be used as Refs 28–30,. as confirmed by this experiments.…”

Section: Resultsmentioning

confidence: 99%

“…However, the change in AR is not obvious with increased CD when the [η] values of P(DMDAAC‐ co ‐AM) are close. This result can be attributed to the increased crimp degree and neighboring group effect of macromolecular chains with increased [η] of P(DMDAAC‐ co ‐AM), which hinders the reaction of P(DMDAAC‐ co ‐AM) with HCHO and TETA 28…”

Section: Resultsmentioning

confidence: 99%

Synthesis of a novel amphoteric chelating polymer flocculant and its performance in Cu²⁺ removal

Liu

Ling

et al. 2012

J of Applied Polymer Sci

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A novel amphoteric chelating polymer flocculant (ACPF) was synthesized. The synthesis involved the copolymerization of dimethyldiallylammonium chloride and acrylamide to prepare poly(dimethyldiallylammonium chloride-co-acrylamide) [P(DMDAACco-AM)], Mannich reaction of P(DMDAAC-co-AM) with triethylenetetramine and formaldehyde to prepare P(DMDAAC-co-AM)graft-TETA, and xanthogenation of P(DMDAAC-co-AM)-graft-TETA with CS 2 and NaOH. The removal performance of ACPF toward Cu 2þ was investigated, and the ACPF structure was characterized. ACPF performance considerably improved at 121-187 mL/g intrinsic viscosity, 20.78-28.32 mol % cationic degree of P(DMDAAC-co-AM), and 22.11-28.44% sulphur content of ACPF. The Cu 2þ removal rate was above 99% at a 1.98 : 1 molar ratio of -CSS À to Cu 2þ . This rate was 5.86% higher than that using polyacrylamidegraft-triethylenetetramine-dithiocarbamate (PAM-graft-TETA-DTC). The zeta potential and sedimentation rate of flocs obtained from ACPF were higher and their volume was smaller than those from sodium triethylenetetramine-multidithiocarbamate and PAM-graft-TETA-DTC at the same sulphur dosage. This result indicates that the positive charges of ACPF polymeric chains effectively neutralize excess negative charges in flocs, which benefits the bridging of flocs with negative charges to promote their formation and growth. These positive charges can also cause the flocs to become larger and tighter, thereby improving flocculation and settling performance.

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“…Normally, salts (retarders) are used to delay the gelation and slow down the cross-linking process. Almost all of the previous gelation kinetics studies have used rheological measurements [14][15][16][17] and nuclear magnetic resonance (NMR) spectroscopy techniques [18,19].…”

Section: Introductionmentioning

confidence: 99%

DSC investigation of the gelation kinetics of emulsified PAM/PEI system

Mohamed

Hussein

Sultan

et al. 2015

J Therm Anal Calorim

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Water production in the oilfields has a negative impact on the production and economy. It is highly desired to shut off water paths without affecting the hydrocarbon zones. Polymer gels are frequently used for water control in oil and gas wells. However, a risk will be taken, which is blocking the oil-producing zones alongside the water zones. Hence, a selective system is proposed, which is based on emulsified polymer gel that contains a water phase which will form a gel, and an oil phase remains mobile to secure the flow of oil. The gels formed in situ by breaking up of an emulsified gel made of an oil phase and an aqueous water-soluble polymers (gelant). Breaking of the emulsion and the subsequent gelation is a function of temperature, time, salinity of mixing water, and concentration of the various components, including surfactants and salts. The gelant was prepared by mixing polyacrylamide (PAM) with a mixing brine and then adding polyethylenimine (PEI) as a cross-linker. Diesel and a surfactant were used to form the emulsified gel. In this study, differential scanning calorimetry (DSC) is utilized to study the emulsified gel reaction kinetics for the first time. The rate of increase in temperature and the final temperature used in DSC were chosen to approximate (mimic) the field injection conditions. The impact of parameters such as temperature, water salinity, surfactant, and retarder type on gelation is investigated to compare the kinetics of the polymeric gels and their emulsified forms. At a given emulsifier concentration, emulsified PAM/PEI has a lower rate of cross-linking (gelation) when compared to that of PAM/PEI. This is most likely due to less heat conducted to the gelant. As a result, the cross-linking density will be less. Ammonium chloride is found to be more efficient than sodium chloride in retarding the gelation process. The type of surfactant is an additional parameter which can be used to control gelation in emulsified gel systems.

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An investigation of the crosslinking of polyacrylamide with formaldehyde using ¹³C nuclear magnetic resonance spectroscopy

Cited by 14 publications

References 3 publications

Chemical modification and synthesizing conditions of nanocomposite hydrogels with high mechanical strength crosslinked by hydrophilic reactive microgels

Chemical modification and synthesizing conditions of nanocomposite hydrogels with high mechanical strength crosslinked by hydrophilic reactive microgels

Synthesis of a novel amphoteric chelating polymer flocculant and its performance in Cu²⁺ removal

DSC investigation of the gelation kinetics of emulsified PAM/PEI system

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An investigation of the crosslinking of polyacrylamide with formaldehyde using 13C nuclear magnetic resonance spectroscopy

Cited by 14 publications

References 3 publications

Chemical modification and synthesizing conditions of nanocomposite hydrogels with high mechanical strength crosslinked by hydrophilic reactive microgels

Chemical modification and synthesizing conditions of nanocomposite hydrogels with high mechanical strength crosslinked by hydrophilic reactive microgels

Synthesis of a novel amphoteric chelating polymer flocculant and its performance in Cu2+ removal

DSC investigation of the gelation kinetics of emulsified PAM/PEI system

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An investigation of the crosslinking of polyacrylamide with formaldehyde using ¹³C nuclear magnetic resonance spectroscopy

Synthesis of a novel amphoteric chelating polymer flocculant and its performance in Cu²⁺ removal