Crosslinked starch-urea formaldehyde (St-UF) as a hydrophilic matrix for encapsulation: studies in swelling and release of carbofuran

Shukla, Parshuram G.; Rajagopalan, Natarajan; Bhaskar, C. Vijaya; Sivaram, Swaminathan

doi:10.1016/0168-3659(91)90073-m

Cited by 36 publications

(15 citation statements)

References 14 publications

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“…Bajpai and Giri (2003)have observed the decrease in release rate and release amount of KNO 3 with increase in crosslinker concentrations in (CMC-g-poly(AAm) hydrogels. Shukla et al (1991) have also observed the similar observation for the release of pesticide from the pesticide loaded polymeric matrix based on starch. Mobility experiments have shown that the use of alginate-based on release system containing chloridazon has reduced the presence of herbicides in the leachate compared to technical products, mainly for chloridazon (Flores Céspedes et al 2013).…”

Section: +3supporting

confidence: 65%

Polysaccharides as safer release systems for agrochemicals

Campos

Oliveira

Fraceto

et al. 2014

Agron. Sustain. Dev.

276

175

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Agrochemicals are used to improve the production of crops. Conventional formulations of agrochemicals can contaminate the environment, in particular in the case of intensive cropping. Hence, there is a need for controlledrelease formulations of agrochemicals such as polysaccharides to reduce pollution and health hazards. Natural polysaccharides are hydrophilic, biodegradable polymers. This article reviews the use of polysaccharides in the form of micro-and nanoparticles, beads and hydrogels. The main points are: (1) slow release formulations minimize environmental impact by reducing agrochemical leaching, volatilization and degradation. For example, 50 % of the encapsulated insecticide chlorpyrifos is released in 5 days, whereas free chlorpyrifos is released in 1 day. (2) Slow release formulations increase the water-holding capacity of soil. (3) Slow release formulations better control weeds in the long run. (4) Polymer-clay formulations store ionic plant nutrients. (5) Polymer hydrogel formulations reduce compaction, erosion, and water run-off. They increase soil permeability and aeration, infiltration rates, and microbial activity, and, in turn, plant performance. In conclusion, polysaccharide formulations can be used for safer use of agrochemicals.

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Section: +3supporting

confidence: 65%

Polysaccharides as safer release systems for agrochemicals

Campos

Oliveira

Fraceto

et al. 2014

Agron. Sustain. Dev.

276

175

View full text Add to dashboard Cite

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“…The addition of methanol was to facilitate the dissolution of the AC in the media. The use of methanol as the dissolution aid for investigating the release of a substance that is not readily soluble in water in an aqueous medium is not uncommon [24][25][26].…”

Section: Preparation Of Releasing Mediummentioning

confidence: 99%

Electrospun cellulose acetate fiber mats containing asiaticoside or Centella asiatica crude extract and the release characteristics of asiaticoside

Suwantong

Ruktanonchai

Supaphol

2008

Polymer

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“…This is expected because as the degree of cross-linking is increased, the hydrophilicity of the matrix is decreased, the matrix structure becomes denser, and, thus, the rate of diffusion of the encapsulant through the swollen matrix decreases. The observed anomaly at X = 0.8 is attributed to two causes: (1) The optimum degree of cross-linking is obtained for a molar ratio of -2.0 (urea: anhydroglucose repeating unit in the starch molecule) at X = 0.6; and (2) microvoids and cracks are produced by the internal stresses caused by the rigid nonhydrophilic UF condensates at X = 0.8. Similar to carbofuran, the n value remains almost constant, 0.40 k 0.01, for samples SlA, SlB, and SlC, indicating that the release mechanism is not affected by a change in the degree of cross-linking.…”

Section: Release Of Solid Encapsulantsmentioning

confidence: 91%

Starch urea‐formaldehyde matrix encapsulation. IV. Influence of solubility and physical state of encapsulant on rate and mechanism of release

Shukla

Rajagopalan

Sivaram

1993

J of Applied Polymer Sci

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SYNOPSISThe influence of the physical state and solubility of the encapsulant on the rate and mechanism of release and swelling of the cross-linked starch-urea formaldehyde ( St-UF) matrix has been studied by encapsulating model organic compounds. The release and swelling data have been analyzed in terms of the generalized equation M J M , = kt" applicable for swellable controlled-release systems. This matrix system shows an inverse relationship of release rate with the cross-link ratio for all the encapsulants studied. The solid encapsulants have n values in the range of 0.22-0.41, indicating a Fickian or anomalous mechanism. Further, the release rate increases with solubility of the encapsulant. The liquid encapsulants have n values in the range of 0.5-1.5, indicating Case I1 or Super Case I1 transport mechanism. The release rates for liquid encapsulants are lower by one to three orders of magnitude than those for solid encapsulants and are not influenced by encapsulant solubility. This indicates a polymer chain relaxation-controlled mechanism of release for liquid encapsulants.

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Crosslinked starch-urea formaldehyde (St-UF) as a hydrophilic matrix for encapsulation: studies in swelling and release of carbofuran

Cited by 36 publications

References 14 publications

Polysaccharides as safer release systems for agrochemicals

Polysaccharides as safer release systems for agrochemicals

Electrospun cellulose acetate fiber mats containing asiaticoside or Centella asiatica crude extract and the release characteristics of asiaticoside

Starch urea‐formaldehyde matrix encapsulation. IV. Influence of solubility and physical state of encapsulant on rate and mechanism of release

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