Surface modification of pyrophyllite for optimizing properties of castor oil-based polyurethane composite and its application in controlled-release fertilizer

The high cost and difficulty in sustainability have hindered the wide application of the general synthetic resins in the controlled-release fertilizers (CRF). Here, the degradable castor oil-based polyurethane (PU) was filled by the natural pyrophyllite (PY) powders, which were pre-modified with few amount (<0.5 %) of NDZ-201 coupling agent though a simple and economic mechanochemical method. Furthermore, the composite materials of PU and the modified PY (MPY/PU) with enhanced comprehensive properties were prepared and applied in CRF. Moreover, the release behaviors of the coated fertilizers were investigated while tuning the addition amount of modifier or the filling amount of MPY, and it was confirmed that the release performance was highly depended on the hydrophobic and mechanical properties of the composite coating. As a result, the best optimized MPY/PU coating exhibited significantly superior performance to the pure PU materials, and the duration of 80 % nitrogen release was more than 40 days. This confirms that the MPY/PU composite is a promising coating material for the CRF granules.(c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The degradable castor oil-based polyurethane (PU) filled with modified pyrophyllite (PY) powders was used as a coating material for controlled-release fertilizers (CRF). The release performance of the coated fertilizers depended on the hydrophobic and mechanical properties of the composite coating, and the optimized MPY/PU coating showed superior performance with a nitrogen release duration of more than 40 days.