Bentonite–Acrylamide Hydrogels Prepared by the Nonmixing Method: Characterization and Properties

Abstract

A significant amount of research has been conducted on bentonite–acrylamide hydrogels. These gels are usually prepared by uniformly mixing bentonite with reactive monomers. Herein, a new preparation method of bentonite–acrylamide hydrogels has been proposed to cater to one novel application of bentonite–acrylamide hydrogels. In this method, bentonite–acrylamide hydrogel was obtained by pressing bentonite into a thin mud cake and extruding a mixed liquor of acrylamide, a cross-linking agent, an initiator, and water into the thin mud cake and then subjecting the system to water-bath curing. The effects of extrusion pressure, extrusion time, and acrylamide concentration on the tensile strength and elemental composition of bentonite–acrylamide hydrogel were investigated. The results show that the tensile strength of the bentonite–acrylamide hydrogel first increased and then tended to be stable with the further increase in extrusion pressure and extrusion time. As the concentration of acrylamide increased, the tensile strength of the bentonite–acrylamide hydrogel increased first and then decreased slightly. With the increase in extrusion pressure, extrusion time, and acrylamide concentration, the contents of C and N elements in the thin mud cake gradually increased and then tended to be stable, which reflects the state of the monomer entering the thin mud cake. In addition, the elemental composition of the bentonite–acrylamide hydrogel was analyzed via the scanning electron microscopy–energy dispersive X-ray spectrometry method, and it was found that the composition of the hydrogel was relatively uniform in the direction of mixed liquor extrusion.

A new insight on relative permeability modifier as conformance control in carbonate reservoir

“…Guo et al [42] mentioned that as the acrylamide concentration increased, the bentonite-acrylamide hydrogel's tensile strength increased first and then decreased slightly. When the acrylamide concentrations were 10 and 20%, the tensile strength of the gel was zero, as no gelation reactions occurred.…”

Preparation and Study of Polyvinyl Alcohol Gel Structures with Acrylamide and 2-Acrylamido-2-methyl-1-propanesulfonic Acid for Application in Saline Oil Reservoirs for Profile Modification

“…The most widely used polymer profile modification systems mainly include polyacrylamide (PAM) and partially hydrolyzed PAM (HPAM). − These systems can be divided into inorganically crosslinked [using Cr­(III), Al­(III), and Zr­(IV) polyvalent metal ions as crosslinkers to form three-dimensional (3D) network gel structures through ionic bonding] − and organically crosslinked (using phenol-formaldehyde, polyethyleneimine, hydroquinone (HQ), and hexamethylenetetramine as crosslinkers to form 3D network gel structures through covalent bonding) − gel systems. In addition, an acrylamide monomer (AM) can form a composite hydrogel with nanocellulose or nano fly ash through free radical polymerization, improving the gel performance, and is used for oilfield profile modification. − Organically crosslinked polymer gels are formed by intermolecular reactions and have higher thermal stability owing to covalent bonds with higher bond energies than ionic bonds. , However, when subjected to high temperature and salinity, the amide groups (−CONH 2 ) on polymer molecular chains can hydrolyze to form carboxyl groups (−COOH) to become HPAM, which can form ionic bonds with polyvalent metal ions and cause dehydration. − Therefore, applications of conventional polymer gels for EOR are restricted as most of the polymer gels cannot withstand high temperature and salinity and restrict the recovery. − Zhu et al , developed a terpolymer gel system formed by organic crosslinkers (phenol, resorcinol, catechol, and HQ).…”

Mussel-Inspired Self-Adhesive, Antidrying, and Antifreezing Poly(acrylic acid)/Bentonite/Polydopamine Hybrid Glycerol-Hydrogel and the Sensing Application

“…The unique lamellar structure of BT not only exhibits the advantage on the higher water absorption capacity, up to 10-fold of its own mass, but also is favorable for the intercalation between water, small molecules, and polymers. The past research results proved that the combination of BT with water-soluble polymers is an effective method to enhance the toughness of hydrogels. , Kheirabadi and coworkers prepared a tough composite hydrogel by incorporating BT with the copolymer of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylic acid (AA)-sodium acrylate (AANa), exhibiting the maximum breaking strength of 700 kPa.…”

“…The past research results proved that the combination of BT with water-soluble polymers is an effective method to enhance the toughness of hydrogels. 28,29 Kheirabadi and coworkers 30 prepared a tough composite hydrogel by incorporating BT with the copolymer of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylic acid (AA)-sodium acrylate (AANa), exhibiting the maximum breaking strength of 700 kPa.…”