Drying and shrinkage of polymer gels
The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 ºC) in presence of Photo-initiator (IrgacureR) and Cross-linker (NN'-methylene bisacrylamide; MBAM). In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM), concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 <FONT FACE=Symbol>´</FONT> 10-10-5.93 <FONT FACE=Symbol>´</FONT> 10-10 m²/s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H2O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.
| Main Authors: | , , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Brazilian Society of Chemical Engineering
2005
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322005000200007 |
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