title: Low molecular weight polylactic acid as a matrix for the delayed release of pesticides.
abstract: Low molecular weight polylactic acid (LMW PLA) was used as a matrix to formulate biodegradable matrix granules and films with bromacil using a melt process. The compatibility of the PLA with bromacil was evaluated. The release characteristics of the formulations were investigated in vitro. The degradation and erosion of the formulations were monitored by pH and gravimetric analysis during the course of release. Various granules and films had similar biphasic release patterns, a delayed release followed by an explosive release. The release rates were independent of bromacil content in the matrix, but varied with the geometry of matrices. The mechanisms of diffusion and erosion were involved in the release. The delayed release of the formulations was dominantly governed by the degradation and erosion of PLA. LMW PLA underwent bulk erosion. LMW PLA-based matrix formulations could thus be useful for the application of pesticides to sensitive targets such as seed treatment.
authors.affiliation: School of Biology, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Richard M
authors.initials: RM
authors.lastname: Wilkins
mesh_terms: D001976:Bromouracil / Q000008:administration & dosage / Q000031:analogs & derivatives*; D003692:Delayed-Action Preparations; D006540:Herbicides; D019344:Lactic Acid / Q000737:chemistry*; D008970:Molecular Weight; D010575:Pesticides; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D006540:Herbicides; D010575:Pesticides; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D001976:Bromouracil; C004590:bromacil