Superabsorbent polymers properties

Nonaka, T. Yamada, K. Watanabe, T. Kurihara, S. Preparation of superabsorbent polymer hydrogels from trialkyl-4-vinylbenzyl phosphonoium chloride-acrylamide-methylenebis-acrylamide copolymer and their properties. J. Appl. Polym. Sci. 2000, 78, 1883-1884. 

Masuda, F. Properties of superabsorbent polymers. In Super absorbent Polymers Kyoritsu Shuppan Tokyo, 1988 51-80 (written in Japanese). 

Sometimes, the ability of certain polymers to repel water is useful— this property is what keeps you dry when you wear a raincoat. Other times, it is desirable for polymers to absorb water. This is why wool socks keep your feet warm by wicking water away from your skin and why a diaper helps keep a baby dry. Cloth diapers are made of cotton, a natural polymer that absorbs water well. Why do disposable diapers hold so much more water than cloth diapers They contain a superabsorbent polymer that can hold hundreds of times its weight in water. In this MiniLab, you will determine how much water the polymers in two different brands of diapers can hold. 

TABLE 4.1 Physical properties of the control and superabsorbent polymer amended soils... 

The principal useful feature of superabsorbent polymers is their ability to absorb aqueous liquids and expand or swell in size. The swollen polymer—a cross-linked pol5uner solution— holds tightly to the liquid and prevents the liquid from being easily squeezed from the expanded structure. The two principal properties of the pol5uner that define their usefulness are the swelling ratio and the elastic modulus of the swollen polymer. 

The intercalation of poly(acrylamide)-montmoriUonite superabsorbing polymer composites (SAPCs) into an aluminate cement matrix leads to a noticeable improvement in the mechanical properties of the hardened cement paste. The addition of as little as 0.6% SAPCs increases the compressive strength from 36.1 to 44.4MPa, the modulus of elashcity from 7.8 to 11.1 GPa, and the split tensile strength from 3.3 to 7.0MPa, for a W/C ratio of 0.4 (Gao et al, 1997). 

In part 3 (context-related inquiry) students eonduet some praetieal assignments, related to the module s theme, about oflier properties and applieations of superabsorbing polymers. The instructional function of conducting fliese projects is to make students aware of the finitfulness of studying fliese chemical concepts. 

Yu, C., Yun-Fei, L., Huan-Lin, T., Hui-Min, T. (2010). Study of carboxymethyl chitosan based polyampholyte superabsorbent polymer I optimization of synthesis conditions and pH sensitive property study of carboxymethyl chitosan-g-poly(acrylic acid-co-dimethyldi-allylammonium chloride) superabsorbent polymer. Carbohydrate Polymers, 81, 365-371. 

A comprehensive overview of the properties of superabsorbent polymers, specific water absorption and desorption behavior of superabsorbent pol5uners in fresh and hardening concrete, the effects of the superabsorbent pol5uners addition on the rheological properties of fresh concrete, the changes of cement paste microstructure and mechanical properties of concrete have been reviewed (42). 

As already described, superabsorbency criteria depend on the absorbent s properties, the absorption measurement method and use method, and the conditions under which it is used with other materials. Therefore in this section we will not define superabsorbency as the maximum absorption of water with respect to the weight of the absorbent. Rather, it will be defined as optimum water absorption based on the purpose of the application. Employing this definition, we will discuss the synthesis of superabsorbent polymers, measurement of water absorption, absorbency and its water absorption characteristics, change of the required properties for superabsorbency in the main areas of, health applications, other superabsorbency of industrial materials, and moisture absorption of general superabsorbent polymers. 

The water uptake of poly(acrylic acid)-type superabsorbent polymers differs markedly depending upon, in general, the chemical property differences of the absorbate, such as the type or concentration of ions in the absorbate, and the presence of a hydrophilic organic solvent in the aqueous solution. 

Since this is currently the most significant application of superabsorbent polymers, many patent applications have been made. Particular effort has been expended to improve the superabsoibency and high performance properties of superabsorbent polymers. 

Table 2 Change in application methods and the required properties of superabsorbent polymers used in disposable diapers.

Let us consider the example of water swelling of sealant materials. If the polymer is able to swell and stop water leakage when in contact with fresh water but it does not swell when in contact with sea water, then it will not have achieved its function as a sealant. It is desirable for these materials to swell to the same degree regardless of the type of water encountered. Therefore, the required property for this application to be superabsorbent is to swell similarly, independent of ion concentration and type in the absorbate. Furthermore, it must absorb as much water as possible (see Fig. 4b/sulfonic acid-type salt resistant superabsorbent polymer, Aquaric CS-7L). 

Properties Required of Superabsorbent Polymers for Communication Cables 412... 

The most important property of superabsorbent polymers is their ability to absorb water. Traditional water-absorbing materials such as cotton, pulp and sponges absorb water into interstices by capillary phenomenon. By contrast, superabsorbent polymer absorbs water into three-dimensional (3D) networks of a erosslinked polymer by the compatibility of polymer chains and water and by osmotic pressure. Hence, superabsorbent polymers laek absorption speed but have a much better water-absorption eapaeity eompared to cotton or pulp. Products that have a high water-absorption property include sanitary produets, such as disposable diapers, eonstmetion materials, mulch, water sealant for electric cables, freshness maintenance materials in the food industry. Of the sanitary products, of the disposable diaper is the best example of a product that has a high waterabsorbing capacity. The superabsorbent polymer is indispensable for disposable diapers, and it drastically improved the performance of disposable diapers. Here, the development and current status of disposable diapers, the structure of disposable diapers in which a superabsorbent polymer is incorporated, and advances in the development of superabsorbent polymers will be described. 

Because porous superabsorbent polymers possess large surface areas as well as chaimels and capillaries for liquid diffirsion, high blood-absorption rates can be expected. As shown in Fig. 4, the lower the bulk density (the property that relates to porosity) of superabsorbent polymers, the higher the blood-absorption rate. Thus, various porous superabsorbent polymers have been developed and their absorbencies are under investigation. 

Superabsorbent polymer sheets have also been developed. If a particulate superabsorbent polymer is crosslinked between particles by a cationic polymer, for example, an amine-epichlorohydrin adduct, a superabsorbent polymer sheet can be prepared [23]. A particulate superabsorbent polymer, cellulose acetate and a plasticizer are dispersed in an appropriate solvent followed by casting onto a nonwoven cloth substrate. Upon irradiation by ultrasound, a superabsorbent sheet can also be prepared [24]. However, such material has poor compatibility with blood and lacks capillary channels. Thus, further improvement is necessary. Accordingly, various new superabsorbent polymers have been developed. Unfortunately, these polymers show insufficient property improvement or are too costly to be commercially available. 

When the antifungal property of a superabsorbent polymer sheet was evaluated (aceording to JIS-Z2911 standards) using a nonnutrient agar... 

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