Ethylcellulose and lignin as bearer polymers in controlled release formulations of chloridazon

Polymeric materials like ethylcellulose and lignin have been used to improve the application of the herbicide chloridazon, preparing controlled release formulations (CRFs). The lignin-based formulations prepared were coated in a Wurster-type fluidized-bed equipment using ethylcellulose and dibutylsebacate. Chloridazon has been successfully trapped, with values of encapsulation efficiency (EE) higher than 94% in all cases. FT-IR and DSC studies indicate the compatibility between polymers and chloridazon in lignin based CRFs. SEM pictures show a homogeneous film in ethylcellulose coated CRFs. Using experimental equations, the time taken for 50% of the active ingredient to be released into water (T-50) was calculated. From the analysis of the T-50 values, it can be deduced that the release rate of chloridazon can be mainly controlled either by selecting the granule size of controlled release lignin matrixes, or by changing the thickness of the coating film and modifying its surface properties adding a plasticizer for ethylcellulose coated CRFs. (C) 2010 Elsevier Ltd. All rights reserved.