A New Apparatus for the Characterization of the Swelling Behavior of Micro-Gel Particles

Selic, E.; Borchard, W.

doi:10.1002/1521-3935(20010201)202:4<516::aid-macp516>3.0.co;2-a

Cited by 6 publications

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References 3 publications

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“…The existence of an induction period is probably caused by the glassy state of the dry polymer where the diffusion coefficient is very small. , The polymer requires a conditioning time, during which is swelled and platicized by water absorption to allow accessibility to complexed sites. This induction period probably exists in all the copolymers but in the copolymer with higher degree of hydrogen bonds is a very limiting factor.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Hydrogen-Bonding Effects on the Dynamic Swelling of P(N-iPAAm-co-MAA) Copolymers. A Case of Autocatalytic Swelling Kinetics

2002

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The swelling kinetics of a series of P(N-iPAAm-co-MAA) copolymers and their P(N-iPAAm) and P(MAA) homopolymers previously soaked under different acidic and neutral conditions have been studied at pH 7 to probe the hydrogen-bonding ability of comonomers. Experimental data analysis has revealed that although the state due to the previous soaking pH does not exert any influence on the equilibrium swelling value of copolymers, it exerts a strong influence on their swelling kinetics. Copolymers gels ranging in composition between 30 and 70 mol % of N-iPAAm previously soaked under acidic conditions exhibit, when subsequently immersed in water at a neutral pH, sigmoidal swelling curves. This behavior has been interpreted according to an autocatalytic mechanism, suggesting that cooperativity on the hydrogen bond disruption controls the swelling behavior. The dynamic swelling of these hydrogels under pH 7 after soaking at this same pH is in very good agreement with a second-order kinetics. This fact corroborates that anomalous features found on the swelling dynamics of these copolymers are related to the strong hydrogen-bonding arrangement between both comonomeric units as well as to the hydrophobicity strongly enhanced by intra-or/and interchain hydrogen bonding.

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Section: Discussion Of Resultsmentioning

confidence: 99%

Hydrogen-Bonding Effects on the Dynamic Swelling of P(N-iPAAm-co-MAA) Copolymers. A Case of Autocatalytic Swelling Kinetics

2002

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“…However, the swelling rate is most often measured by determining the specific absorbency as a function of time, for example, by means of the centrifuge capacity analysis. An absorption rate may also be obtained from data of swelling vs time using the demand absorbency method (48).…”

Section: Analytical and Test Methodsmentioning

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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Superabsorbent Polymers

Buchholz

2002

Encyclopedia of Polymer Science and Technology

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Superabsorbent polymers are very high molecular mass, cross‐linked polyelectrolytes that can absorb more than 10 times their mass of water or aqueous solutions. The commercially available superabsorbent polymers are alkali matal salts of poly(acrylic acid) cross‐linked with multifunctional monomers. The polymers are usually made by means of free‐radical‐initiated polymerization of an aqueous solution of the monomers, followed by drying the resulting hydrogel, and grinding the dry polymers to a granular powder. The principal use of superabsorbent polymers is as a liquid absorbent in baby diapers, feminine hygiene products, and adult incontinence products. Smaller volumes are used in food packaging and in water‐blocking tapes for electrical and telecommunication cables. Total global usage of superabsorbent polymers in 2001 amounted to about 1093 kt.

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A New Apparatus for the Characterization of the Swelling Behavior of Micro-Gel Particles

Cited by 6 publications

References 3 publications

Hydrogen-Bonding Effects on the Dynamic Swelling of P(N-iPAAm-co-MAA) Copolymers. A Case of Autocatalytic Swelling Kinetics

Hydrogen-Bonding Effects on the Dynamic Swelling of P(N-iPAAm-co-MAA) Copolymers. A Case of Autocatalytic Swelling Kinetics

Superabsorbent Polymers

Superabsorbent Polymers

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