Natural rubber base matrix containing Calendula officinalis plant as a source of molluscicidal saponin

Natural rubber (NR) has been used as a binding matrix for Calendula officin alis, where it is used as a vulcanizate. Various doses of the plant coverin g the range from 100 up to 200 parts per 100 of rubber (phr) were found sui table for processing conditions using conventional rubber mixing equipment. The release rate of saponin was extended to over 4 months. Incorporation o f fillers, such as HAF and Hisil, in the compounded rubber decreased the re lease of saponin; especially in the first period of immersion. The amount o f saponin released was affected by the environmental temperature and the ty pe of fillers present in the formulations. The scanning electron micrograph s illustrate the presence of a tortuous pass and pore structure that formed after soaking in water and leaching process occurred. (C) 1999 Elsevier Sc ience B.V. All rights reserved.