Kinetics of water absorbency in AA/AMPS copolymers: applications of a diffusion–relaxation model

Rosa, Fátima; Bordado, João; Casquilho, Miguel

doi:10.1016/s0032-3861(01)00596-1

Cited by 58 publications

(33 citation statements)

References 13 publications

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“…and 2-acrylamido-2-methylpropanesulfonic acid (1,2) are the principal ionizable monomers useful for making superabsorbent polymers. Other comonomers such as acrylamide and N-isopropylacrylamide can also be incorporated into the polymer chain.…”

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confidence: 99%

Superabsorbent Polymers

Buchholz¹

2006

Encyclopedia of Polymer Science and Technology

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IntroductionSuperabsorbent polymers are very high molecular mass, cross-linked Polyelectrolytes (qv) that can absorb or imbibe more than ten times their mass of water or aqueous solutions. In order to absorb this large quantity of aqueous fluid, the polymers must be only slightly cross-linked so that the polymer chains can adopt widely spaced configurations. And in order to remain largely insoluble, while at the same time being highly expanded, the polymer chains must have very high molecular mass so that the small number of cross-links connect together all the chains. Cross-linked polyelectrolytes absorb more aqueous liquid than do neutral polymers as a result of the added osmotic, swelling pressure of the counterions that balance the high electric charge of the ionized functional groups spaced along the polymer chains (see POLYELECTROLYTES).Although any high molecular mass, cross-linked polyelectrolyte can function as a superabsorbent polymer, the commercially available superabsorbent polymers are alkali metal salts of poly(acrylic acid) cross-linked with multifunctional cross-linkers (see ACRYLIC (AND METHACRYLIC) ACID POLYMERS). Most often the cross-links are formed from comonomers that are incorporated into the polymer during the free-radical-initiated addition polymerization. Common cross-linkers are di-and tri-acrylates or methacrylates. The polymer chains can also be crosslinked after the main polymer chains have been formed. In this case, the crosslinker is multifunctional with groups that can react with the carboxylic acid or carboxylate groups present along the polymer chains. Examples of this type of cross-linker are polyols, polyepoxides, polyamines, and the like. Most commonly, the polymers are made by means of free-radical-initiated polymerization of an aqueous solution of the monomers, followed by drying the hydrogel that is formed and grinding the dry polymer to a granular powder.The principal use of superabsorbent polymers is as a liquid absorbent in disposable hygiene products, which include baby diapers, feminine hygiene products, and adult incontinence products. Smaller volume uses include liquid absorbent pads for packaged meats and water-blocking tapes and coatings for electrical and telecommunication cables.

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confidence: 99%

Superabsorbent Polymers

Buchholz¹

2006

Encyclopedia of Polymer Science and Technology

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“…27 Calculations were performed using the Microsoft Excel program (Office Professional Version 2003).…”

Section: Resultsmentioning

confidence: 99%

Method and Model for the Analysis of Gel-Blocking Effects during the Swelling of Polymeric Hydrogels

Wack

Ulbricht

2006

Ind. Eng. Chem. Res.

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This paper focuses on a method to determine the swelling pressure of polymeric hydrogels. The method is based on determining the swelling pressure at a defined volume of swelling that is smaller than the volume the gel can attain by free swelling to equlibrium. Data for one type of polymer particles made from weakly cross-linked and partly neutralized poly(acrylic acid) are presented for swelling in deionized water. For polymer volume fractions (φ P ) in the range of 0.05-0.30, swelling pressures in the range of 0.25-4.31 MPa were obtained. The kinetic data are discussed with a combined diffusion-relaxation model for low and medium polymer volume fractions. A novel model is presented for higher polymer volume fractions. The mechanism of the gel-blocking effect that is evident in this φ P range is explained and considered in the novel model, in the form of a blocking factor. The results obtained may be used for the design of improved sealing concepts that are based on "super absorbing polymers".

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“…As several other studies have concluded, this can be attributed to a higher water affinity, which attracts water molecules during absorption [10,[21][22][23][24]. This attraction can cause swelling within the cavities of the polymer network, which further increases M ∞ (%) and D. The diffusion coefficients of individual layers were also compared with those of multi-layer coatings as shown in Table 3.…”

Section: Water Uptake Processmentioning

confidence: 96%

Water Absorption and Degraded Stress Relaxation Behavior in Water-Borne Anticorrosive Urethane/Epoxy Coatings

Takeshita¹,

Becker²,

Sakata³

et al. 2015

JCCE

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Abstract:The kinetics of water absorption in water-borne anticorrosive urethane/epoxy coatings, which were actually introduced in the industrial field, are studied. It is found that the high water affinity of a water-borne coating supports a higher saturated water content, M ∞ , and helps to facilitate absorption D. The three parameters of stretched exponential function called the William-Watt equation, E o , τ, and β, are determined to fit the degraded stress relaxation behavior in the water absorption process because this function quantitatively describes the relaxing ability and has been successfully used by a number of researchers. An increasing in the water content is shown to correlate strongly with a decrease in E o and β early in the absorption process between M t /M ∞ = 0 and M t /M ∞ ≈ 0.5. The adhesive characteristics of the coatings are correlated with water content, and shown to exhibit higher cohesive failure in coating epoxies under saturated conditions. This suggests that water interferes with the intermolecular bonding between polymer chains which degrades the bulk materials ability to diffuse stress concentrations and reduces its overall strength.

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Kinetics of water absorbency in AA/AMPS copolymers: applications of a diffusion–relaxation model

Cited by 58 publications

References 13 publications

Superabsorbent Polymers

Superabsorbent Polymers

Method and Model for the Analysis of Gel-Blocking Effects during the Swelling of Polymeric Hydrogels

Water Absorption and Degraded Stress Relaxation Behavior in Water-Borne Anticorrosive Urethane/Epoxy Coatings

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