Superabsorbent polymer composites: does clay always improve properties?

Kabiri, Kourosh; Hesarian, S.; Zohuriaan‐Mehr, M. J.; Ahmad, Jamal; Boohendi, H.; Pourheravi, M. R.; Hashemi, Seyed Ali; Omidian, Hossein; Fathollahi, Sara

doi:10.1007/s10853-011-5627-0

Cited by 23 publications

(14 citation statements)

References 37 publications

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“…In this part of research, the effects of two redox initiators (I1 and I2) are investigated. The samples have been prepared using crosslinker P. Initiators I1 and I2 are experimentally differed by the index of gelation time in the reaction15; they stand for the short and long time of gelation, respectively 16…”

Section: Resultsmentioning

confidence: 99%

Effects of structural variables on AUL and rheological behavior of SAP gels

Ramazani-Harandi

Zohuriaan‐Mehr

Yousefi

et al. 2009

J of Applied Polymer Sci

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The swelling properties of superabsorbent polymers (SAPs) under real conditions are extremely important for selecting the material suitable for a given application, e.g. feminine napkin or agriculture. This new practical research represents deeper synthetic and physicochemical studies on the structure-property relation in acrylic SAP hydrogels and composites. Thus, the values of saline-absorbency under load (AUL; a measurable simulation of the real circumstances of SAP applications, at pressures 0.3-0.9 psi) were measured for the SAP or SAP composite samples prepared under different conditions, i.e. type and content of crosslinker, type and concentration of initiator, percentage of inorganic filler (kaolin), and type and percentage of porosity generators. The samples were subsequently used to determine the rheological and morphological characteristics. Dynamic storage modulus (G 0 ) measurements were carried out at constant strain in a wide range of frequency. Linear correlations were frequently found to be active between AUL and G 0 data over the rubber-elastic plateau. Thus, for a given SAP:The coefficient k total is a function of (nature and content of crosslinker, initiator, inorganic component, particle morphology, etc.). Therefore, the easily measured AUL values could be simply correlated to the main synthesis variables and molecular structure of SAP gels through a rheological material function (G 0 ).

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Section: Resultsmentioning

confidence: 99%

Effects of structural variables on AUL and rheological behavior of SAP gels

Ramazani-Harandi

Zohuriaan‐Mehr

Yousefi

et al. 2009

J of Applied Polymer Sci

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“…Because of their excellent properties, these SAPs are already well established in various applications, such as disposable diapers, hygienic napkins, cement, drug delivery systems, sensors and agriculture [1]. In such applications high water absorbency or water retention is essential; therefore, [2,3] attempts have been made to improve these absorbent polymers by enhancing their absorbency, gel strength and absorption rate by manipulating the synthesis conditions, such as solvent [4], cross-linking degree [5] and monomer composition. Their use for agriculture-based applications has shown promising results, however in order to reduce cost and effi cacy, very high water absorbency and retention per unit weight of SAPs are essential.…”

Section: Introductionmentioning

confidence: 99%

Effect of cross-linker and initiator concentration on the swelling behaviour and network parameters of superabsorbent hydrogels based on acrylamide and acrylic acid

Singhal

Tomar

Nagpal

2009

Int J Plast Technol

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Poly (acrylamide-co-acrylic acid) [poly (AAm-co-AAc)]-based hydrogels were prepared by varying the cross-linking agent concentration (NMBA) in the range of 0.0077% to 0.077%. The effect of the NMBA content on swelling parameters, such as water absorbency, swelling ratio on the hydrogel was studied by keeping two monomers content, that is, AAm and AAc constant. The effect of KPS as an initiator in the range of 0.1% to 0.5% on the water absorbency of the hydrogels was also studied. The swelling value could be modulated in a great range by varying the cross-linking agent (NMBA) or initiator (KPS) concentration at fi xed monomer concentration. The synthesized hydrogels were characterized by FTIR, SEM and network parameters, such as average molecular weight between cross-links (Mc), cross-link density (q) and mesh size (ξ). The experimental results showed that the equilibrium water absorbency decreases from 707.23 to 389 with increasing the NMBA content from 0.0096 % to 0.0385%. The network parameters, such as average molecular weight between cross-links (Mc) were decreased from 2.33 x 10 12 to 2.30 x 10 11 and cross-link density (q) decreased from 3.07 x 10 -11 to3.09 x 10 -11 ; although mesh size (ξ) increased from 3.00 x 10 6 to 8.89 x 10 6 with increase in percentage of NMBA content from 0.009265% to 0.077%. The equilibrium water absorbency of various hydrogels were studied in distilled water and different types of saline solutions, which exhibited that hydrogels have higher equilibrium water absorbency in 0.009% saline (NaCl) solution than in 0.09% and 0.9% saline solutions. From the results it was clear that water absorbency increased from 302 to 573 g water/g sample with increasing the KPS content from 0.1 to 0.5%.

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“…It means that fewer junctions are formed between the chains and consequently the crosslink densities are diminished. Decreased crosslink densities lead to enhanced swelling capacities 13. According to Figures 2 and 4, the slope of the swelling capacity increase for the SAP prepared by the pair APS/TMEDA is much more than that of the APS/SMBS pair.…”

Section: Resultsmentioning

confidence: 92%

“…Numerous papers have been published in field of SAP hydrogels in last two decades. Different aims were considered in these papers such as enhancing absorption rate through using porogens,5, 6 improving gel strength mostly by preparing superabsorbent composites or nanocomposites,7–9 preparing hybrid superabsorebnts by simultaneous use of natural polymers and acrylic monomers,10, 11 or investigation of reaction parameters such as initiator concentration, monomer concentration, reaction temperature or comonomer content on swelling properties 12, 13. There are nearly 1150 papers on superabsorbents published during years 1976–2008.…”

Section: Introductionmentioning

confidence: 99%

Residual monomer in superabsorbent polymers: Effects of the initiating system

Kabiri

Zohuriaan‐Mehr

Bouhendi

et al. 2009

J of Applied Polymer Sci

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Minimized residual monomer is an essential requirement particularly in hygienic, pharmaceutical, and food packaging polymer products such as superabsorbent polymers (SAPs). The present article is the first non-patent report on the study of a highly effective polymerization variable (e.g. initiator) on the residual monomer of SAPs based on partially neutralized acrylic acid. Two persulfate systems, i.e. ammonium persulfate (APS)/sodium metabisulfite (SMBS) and APS/tetramethyl ethylenediamine (TMEDA), were examined to initiate the free-radical polymerization at room temperature. It was shown that chromatographically measured residual monomer and swelling capacity was strongly dependent on the type and concentration of the initiator. A kinetic model was also derived to describe the experimental results. Dissociation rate of initiation system was recognized to be a key factor to obtain a SAP with low residual monomer. It was found that, in aqueous solution polymerization, the effect of a slowly dissociating system such as APS/TMEDA on decreasing the residual monomer was much higher than that of a rapidly dissociating system like APS/SMBS. Under selected conditions, residual monomer could be reduced up to 5327 AE 138 and 1715 AE 44 ppm for APS/SMBS and APS/TMEDA initiating systems, respectively.

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Superabsorbent polymer composites: does clay always improve properties?

Cited by 23 publications

References 37 publications

Effects of structural variables on AUL and rheological behavior of SAP gels

Effects of structural variables on AUL and rheological behavior of SAP gels

Effect of cross-linker and initiator concentration on the swelling behaviour and network parameters of superabsorbent hydrogels based on acrylamide and acrylic acid

Residual monomer in superabsorbent polymers: Effects of the initiating system

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