Swelling capacity

The swelling capacity of a polymer is the amount of a liquid that can be absorbed by it. This test can done by two methods:

1. Beaker test method ^[1]
2. Tea bag test method ^[2]

Beaker test method

In this method

• A small amount of superabsorbent polymer material is taken (0.1g) and it is placed in the beaker.
• 100 ml of deionized water is poured into the beaker.
• After 20 min the swollen polymer was separated by using filter paper
• By weighing the polymer, one can find the swollen capacity of the SAP material. ^[3]

Tea bag test method

• In this method, 0.1 g of SAP material is placed into a permeable bag, which is suspended over excess water in a beaker.
• Wait 20 min. and weigh the bag and then calculate the percentage of swelling through the following formula:

  (w2-w1)/(w1)  %

  w1= weight of the polymer (Before swelling)

  w2= weight of the polymer (After swelling)

• Note: Filter paper only for removing water.

Schroeder's paradox

Main article: Schroeder's paradox

Some polymers exhibit larger experimentally measured swelling capacity when immersed in pure liquid compared to testing with saturated vapor. This phenomenon is known as the Schroeder's paradox.

References

1. Anandan, Dhivyaa; Madhumathi, G.; Nambiraj, N. Arunai; Jaiswal, Amit K. (June 15, 2019). "Gum based 3D composite scaffolds for bone tissue engineering applications" . Carbohydrate Polymers. 214: 62–70. doi:10.1016/j.carbpol.2019.03.020. ISSN   0144-8617. PMID   30926008. S2CID   88481556.
2. Zhong, Peihua; Wang, Jun; Wang, Xiaoxian; Liu, Jiaping; Li, Zhen; Zhou, Yichuan (2020). "Comparison of Different Approaches for Testing Sorption by a Superabsorbent Polymer to Be Used in Cement-Based Materials". Materials. 13 (21): 5015. Bibcode:2020Mate...13.5015Z. doi: 10.3390/ma13215015 . ISSN   1996-1944. PMC   7664450 . PMID   33172166.
3. Yang, Zijiang; Arakawa, Hisayuki (2023). "A beaker method for determination of microplastic concentration by micro-Raman spectroscopy". MethodsX. 11. doi:10.1016/j.mex.2023.102251. PMC   10336159 . PMID   37448948.