3. Swelling Capacity Swelling is one of the distinctive physical properties of the gel copolymer, which is related to the ability to absorb water. The gel ability to absorb water is influenced by the present of free functional groups in the copolymer, such as -OH, -NH2, and -SO3H and can also be influenced by the environment, for example, the alteration in pH, temperature, and electrical current (Erizal et, al., 2002). Swelling properties that is possessed by this gel copolymer can be used as a determination of the swelling ability of the copolymer, which is based on the value of swelling ratio until the maximum limit gel to swells in particular immersion time. The swelling ratio values is obtained through the mass ratio between the gel which …show more content…
The conditions that happening are known as protonation process. Positive ions arising from -OH2+ and -NH3 + pull with the anion PO43-, so that will be captured in the copolymer. Then to process the phosphate desorption in distilled water almost like at pH 3.09 (H+ height) solution. This is presumably due to ionic interactions of phosphate anion with -NH3+ that more slightly due to the number of H + only comes from natural dissociation process of distilled water. Moreover, the desorpsi interaction of phosphate in the copolymer is more dominated by inter and intra-molecular interactions and hydrogen bonding between the functional groups in the copolymer with phosphate anion. At pH 10.05 solution is suspected OH- ion will take the H atom in -NH2, so that it make -NH- group because an excess of electrons. The negatively charged copolymer repel each other with a phosphate anion so that the amount of phosphoric is out of the copolymer