Structurally stable polyvinyl alcohol/sodium alginate-based optimally designed electrospun mats as mechanistically robust controlled-urea-release-systems
Krishna Priyadarshini Das, Deepika Sharma, Bhabani K. Satapathy
Abstract
The present study deals with the development of uniform, bead-free, and urea-loaded PVA/SA-based sustainable electrospun fibrous constructs as a controlled release fertilizer system. Taguchi L 9 OA was used to predict the optimal level of control parameters i.e., urea loading (∼ 45 phr), flow rate (∼ 1 ml/h), polymeric concentration (∼ 8 wt%), and an applied voltage of ∼ 25 kV, to fabricate EMs with minimum fiber diameter (∼ 0.208 µm) and diametral variation (∼ 0.017 µm). Microstructural analysis confirmed the presence of hydrogen bonding interactions between urea and the polymer matrix , as well as successful ionic crosslinking. The contact angle and thermogravimetric analysis indicated an increase in hydrophobicity (from ∼ 30.64º to ∼ 74.13º) and thermal stability (from 164 ºC to ∼ 290 ºC) for PVA/SA-based EMs upon urea incorporation and post crosslinking, respectively. Further, the effect of urea loading and crosslinking on swelling and degradation behavior revealed a subsequent increase in water absorption capacity up to ∼ 296 % accompanied by a decrease in degradation rate up to ∼ 13%. The swelling behavior of EMs exhibited a desirably good level of pH level, salt/alkali solution sensitivity, and water retention potential lasting up to ∼16 days in soil. Spectroscopic analysis revealed a non-Fickian diffusion-induced sustained release of urea in water (> 21 days) and soil media (> 30 days). Soil burial studies of crosslinked urea-loaded EMs exhibited excellent biodegradability (> 80 % in 60 days) and structural stability (∼30 days). Thus, the study demonstrated the design of mechano-functionally engineered urea-loaded optimized PVA/SA-based EMs as potential controlled nutrient release substrates with improved and sustainable physicomechanical performance for agricultural practices.