Modified carrageenan. 6. crosslinked graft copolymer of methacrylic acid and kappa-carrageenan as a novel superabsorbent hydrogel with low salt- and high pH-sensitivity

2005 ◽  
Vol 13 (6) ◽  
pp. 483-490 ◽  
Author(s):  
A. Pourjavadi ◽  
A. M. Harzandi ◽  
H. Hosseinzadeh
Keyword(s):  
Graft Copolymer ◽  
Methacrylic Acid ◽  
Ph Sensitivity ◽  
Superabsorbent Hydrogel ◽  
High Ph ◽  
Low Salt ◽  
Kappa Carrageenan

A new salt-resistant superabsorbent hydrogel based on kappa-carrageenan

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Hossein Hosseinzadeh
Keyword(s):  
Chemical Structure ◽  
Graft Copolymerization ◽  
Salt Solutions ◽  
Superabsorbent Hydrogel ◽  
Swelling Capacity ◽  
Low Salt ◽  
Free Radical Initiator ◽  
Crosslinker Concentration ◽  
Kappa Carrageenan ◽  
Very High

AbstractIn this work, a novel biopolymer-based superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of 2-hydroxyethyl acrylate (HEA) onto kappa-carrageenan, using potassium persulfate (KPS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The chemical structure of the hydrogels was confirmed by FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The certain variables of the graft copolymerization (i.e. the monomer, the initiator, the polysaccharide, and the crosslinker concentration) were systematically optimized to achieve a hydrogel with maximum swelling capacity. The swelling ratio in various salt solutions was also investigated in detail. Since this hydrogel exhibited a very high absorptivity in saline, it may be referred to as low salt sensitive superabsorbent. The swelling of superabsorbing hydrogels was also measured in solutions with pH ranging from 1 to 13.

Adhesive properties of aluminum-containing functionalized polymer composites obtained in the process of mechano-chemical modification

2021 ◽  
Vol 10 ◽  
pp. 27-36
Author(s):  
K. V. Allahverdiyeva ◽  
Keyword(s):  
Maleic Anhydride ◽  
Polymer Matrix ◽  
Graft Copolymer ◽  
Methacrylic Acid ◽  
Graft Copolymers ◽  
Aluminum Foil ◽  
Adhesive Properties ◽  
Pressing Temperature ◽  
Type Of Fracture ◽  
Dispersed Aluminum

The influence of the concentration of finely dispersed aluminum and compatibilizer on the resistance to peeling of aluminum foil from the surface of a composite based on low density polyethylene and high density polyethylene is considered. To improve the compatibility of the filler with the polymer matrix, a compatibilizer was used, which is a graft copolymer of polyethylene of various grades with methacrylic acid and maleic anhydride. Copper and aluminum foil was used as a substrate. It is shown that the introduction of a compatibilizer into the composition of aluminum-filled composites improves their peeling resistance. It has been found that if an aluminum filled compatibilizer is used directly as an adhesive, then the peeling resistance of copper and aluminum foil is significantly increased. Graft copolymers of polyethylene with maleic anhydride have the highest peel resistance values. The results of the study of the influence of the pressing temperature on the type of adhesive failure are presented. It is shown that with an increase in the pressing temperature, a mixed type of adhesive destruction is observed. It has been experimentally proved that, in percentage terms, the cohesive type of fracture prevails in composites where graft copolymers are used as a polymer matrix. It was found that a 100 % cohesive type of fracture is observed in foil-clad composites pressed at a temperature of 190 °C, where a graft copolymer of polyethylene with methacrylic acid or maleic anhydride is used as an adhesive.

Polyethylenimine wrapped mesoporous silica loaded benzotriazole with high pH-sensitivity for assembling self-healing anti-corrosive coatings

2020 ◽  
Vol 253 ◽  
pp. 123425 ◽  
Author(s):  
Jiaxin Wen ◽  
Jinglei Lei ◽  
Jinlong Chen ◽  
Lei Liu ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Ph Sensitivity ◽  
Self Healing ◽  
High Ph

Preparation and swelling behaviour of a novel anti-salt superabsorbent hydrogel based on kappa-carrageenan and sodium alginate grafted with polyacrylamide

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Ali Pourjavadi ◽  
Hossein Ghasemzadeh ◽  
Hossein Hosseinzadeh
Keyword(s):  
Sodium Alginate ◽  
Graft Copolymerization ◽  
Weight Ratio ◽  
Homogeneous Solution ◽  
Water Soluble ◽  
Swelling Kinetics ◽  
Salt Solutions ◽  
Superabsorbent Hydrogel ◽  
Swelling Capacity ◽  
Kappa Carrageenan

Abstract A novel superabsorbent hydrogel was synthesized via crosslinking graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (κC) and sodium alginate (Na-Alg) backbones in a homogeneous solution. Methylenebisacrylamide (MBA) and potassium persulfate (KPS) were applied as water-soluble crosslinker and initiator, respectively. FTIR spectroscopy was used for confirming the structure of the final product. A mechanism for superabsorbent hydrogel formation was also suggested. The parameters affecting the swelling capacity of the synthesized hydrogel, i.e., κC-Alg weight ratio, concentration of AAm, MBA and KPS, as well as reaction temperature were systematically optimized for obtaining maximum absorbency. The swelling capacity of hydrogels was also measured in various salt solutions (LiCl, NaCl, KCl, MgCl2, CaCl2, SrCl2, BaCl2, and AlCl3). Due to their high swelling ability in salt solutions, the hydrogels may be referred to as ‘anti-salt superabsorbent’ polymers. The overall activation energy for the graft copolymerization reaction was found to be 374 kJ/mol. The swelling kinetics of the hydrogels in distilled water and in saline solution (0.9 wt.-% NaCl) was investigated.

Heterophase grafting polymerization of methacrylic acid onto poly(caproamide) fibres and the structure of the graft copolymer

1991 ◽  
Vol 33 (3) ◽  
pp. 575-580
Author(s):  
L.G. Kazaryan ◽  
V.A. Vasil'ev ◽  
N.V. Smirnova ◽  
G.A. Gabrielyan ◽  
L.S. Gal'braikh
Keyword(s):  
Graft Copolymer ◽  
Methacrylic Acid ◽  
Grafting Polymerization

Modeling Equilibrium Swelling of a Dual pH- and Temperature-Responsive Core/Shell Hydrogel

2016 ◽  
Vol 08 (03) ◽  
pp. 1650039 ◽  
Author(s):  
N. Hamzavi ◽  
A. D. Drozdov ◽  
Y. Gu ◽  
E. Birgersson
Keyword(s):  
Ph Sensitivity ◽  
Core Shell ◽  
Polymer Gel ◽  
Stimuli Responsive ◽  
Degree Of Ionization ◽  
High Ph ◽  
The Core ◽  
Ionic Core ◽  
Ph Values ◽  
Equilibrium Swelling

The equilibrium swelling of a dual stimuli-responsive core/shell hydrogel is studied by a thermodynamic model. This hydrogel shows thermo-sensitivity as well as pH-sensitivity. The model captures the inhomogeneous swelling of core/shell hydrogels and also, accounts for temperature and pH sensitivity. The predictions of this model are verified with the swelling experiments of a core/shell microgel comprising poly N-isopropyl acrylamide (pNIPAM) and acrylic acid (AAc). The model calculates the equilibrium swelling within the ionic core and the neutral shell. Simulation results can reproduce the equilibrium swelling-temperature curves of this microgel at different pH values considering the delay in the volume phase transition temperature (VPTT) of the ionic polymer gel (pNIPAM-co-AAc) in the core. Two transition points are found in the equilibrium swelling behavior of the hydrogel akin to the VPTTs of the core and shell domains at high pH values of bath solutions. Likewise, the degree of ionization in the core domain is predicted to have a two-step transition behavior corresponding to the VPTTs of the core and shell domains at high pH values of bath solutions. It is shown that the equilibrium swelling of the ionic core is mainly influenced by the electrostatic repulsion between bound charges rather than the ionic pressure. Furthermore, it is determined that the maximum radial stress occurs at the core/shell interface and reaches its maximum value about the VPTT of the core.

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