A Novel Superabsorbent Polymer from Crosslinked Carboxymethyl Tragacanth Gum with Glutaraldehyde: Synthesis, Characterization, and Swelling Properties.

Yahya Bachra,Ayoub Grouli,Mohammed Talbi,Fouad Damiri,Mohammed Berrada,Nicholas Dunne

doi:10.1155/2021/5008833

Yahya Bachra, Ayoub Grouli + Show 4 more

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https://doi.org/10.1155/2021/5008833

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Abstract

Nowadays, current global environmental problems include measures to eliminate or reduce the negative impact of chemicals from petroleum sources and, therefore, the use of materials from natural resources is increasingly recommended. In this context, natural-based superabsorbent polymers derived from polypeptides and polysaccharides have undergone chemical and biochemical modifications to improve their ability to absorb and retain large amounts of liquids. In the present paper, a new process has been used to overcome the side effects of radical polymerization in the manufacture of conventional polyacrylate superabsorbents (SAPs). Tragacanth gum (TG) was selected to prepare a new superabsorbent material (CMTG-GA) based on carboxymethyl tragacanth (CMTG) crosslinked with glutaraldehyde (GA). The characterization of the polymer was carried out by FTIR, TGA, XRD, and SEM. The effect of the amount of crosslinking agent and the pH on the water absorption capacity was also examined. Subsequently, swelling studies were performed using free swelling capacity (FSC) and centrifuge retention capacity (CRC) techniques in distilled water, tap water, and saline solution. The results showed that the CRC of the new material is not less than 42.1 g/g, which was observed for a ratio of 20% by weight of GA to CMTG. Likewise, the maximum absorption results were 43.9 and 32.14 g/g, respectively, for FSC and CRC at pH 8.0. In addition, a comparison of the swelling capacities of the synthesized product with a commercial SAP extracted from a baby diaper, well known in the Moroccan market, showed that the performances were very similar.

Highlights

It is well known that superabsorbent polymers (SAPs) are highly consumable products in everyday life, and the demand for products prepared with these polymers is very high [1]. e products currently on the market are almost entirely synthetic materials derived from petroleum, which have negative effects on the environment on the one hand and, on the other hand, their price is relatively high and depends on the market price of petroleum [2]. e step of investing in the research and development of alternatives is very promising.SAPs have high water absorption due to the increase in specific surface area, resulting in greater exposure of water to hydrophilic groups in the polymer backbone
The swelling capacity in water can be improved by increasing the hydrophilic parts and the hydrogen bonds of the polysaccharide backbone. This synthesis aimed to increase the swelling capacity of Tragacanth gum (TG) to convert it into a superabsorbent polymer. e process consisted of increasing the number of anionic groups on the glycosidic chains and partially crosslinking these chains by an organic synthesis instead of radical polymerization based on acrylic or acrylamide monomers
According to the experimental results, Fourier Transform Infrared Spectroscopy (FTIR) analysis has emphasized the confirmation of the formation of the crosslinked polymer. e thermal properties of TG, carboxymethyl tragacanth (CMTG), and CMTG-GA are strongly influenced by the crosslinking of the polymer chains. e TGA has shown better thermal stability of the crosslinked product compared with CMTG and pure tragacanth gum

Summary

Introduction

SAPs have high water absorption due to the increase in specific surface area, resulting in greater exposure of water to hydrophilic groups in the polymer backbone. Ese include hydrogen bonding, the effect of crosslinking, and the content of hydrophilic groups in the polymer backbone such as carboxylate ions in the case of anionic polymers. Petrochemical-based SAPs are most often technically prepared by radical polymerization of vinyl monomers in the presence of multifunctional crosslinking agents [5, 6]. It is clear that synthetic polymers suffer from such disadvantages as environmental pollution and toxicity of the synthesis process, side effects of traces of initiator and residual acrylic monomers, poor consumer compliance, and sometimes high price. Eir synthesis requires a long development time compared with natural polymers [7,8,9]. Natural SAPs are prepared from polypeptides or polysaccharides such as cellulose, starch, agarose, chitosan, alginates, carrageenan, and their derivatives. ese polymers lend themselves to chemical and biochemical synthesis modifications to improve their ecological characteristics [10,11,12]

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