Effects of Processing Conditions on the Properties of Monoammonium Phosphate Microcapsules with Melamine-Formaldehyde Resin Shell

Shenjie Han; Jingpeng Li; Qingyun Ding; Jian Zang; Yulian Lu; Longfei Zhang; La Hu

doi:10.3390/polym15142991

Effects of Processing Conditions on the Properties of Monoammonium Phosphate Microcapsules with Melamine-Formaldehyde Resin Shell

Polymers (Basel). 2023 Jul 10;15(14):2991. doi: 10.3390/polym15142991.

Authors

Shenjie Han¹, Jingpeng Li², Qingyun Ding³, Jian Zang³, Yulian Lu⁴, Longfei Zhang⁵, La Hu⁶

Affiliations

¹ Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng 224051, China.
² Key Laboratory of High Efficient Processing of Bamboo of Zhejiang Province, China National Bamboo Research Center, Hangzhou 310012, China.
³ College of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China.
⁴ School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng 224051, China.
⁵ Key Laboratory of Wood Science and Technology of State Forestry Administration, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China.
⁶ Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Engineering Research Center of Masson Pine of State Forestry Administration, Guangxi Forestry Research Institute, Nanning 530002, China.

Abstract

To develop monoammonium phosphate (MAP) as a novel acid source for durable intumescent fire retardants (IFR), MAP microcapsules (MCMAPs) containing MAP as the internal core and melamine-formaldehyde (MF) as the external shell were prepared by in situ polymerization in this study. The influences of synthesis conditions (including reaction temperature, polymerization time, and reaction pH value) on the properties of obtained MCMAPs (MAP content, yield, morphologies, and thermal properties) were then investigated systematically. The morphologies, chemical structures, and thermal properties were characterized by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetry analyzer (TGA). The results show that MAP was well encapsulated by MF resin. No microcapsules are obtained at <55 °C or with polymerization times <1 h. Optimal preparation conditions of reaction temperature, polymerization time, and reaction pH value are 75 °C, 3 h, and 5.5, respectively. Those results provide process reference and theoretical basis for preparing MCMAPs and could promote the application of MAP microcapsules in wood flame-retardant materials.

Keywords: in situ polymerization; melamine-formaldehyde; microcapsule; monoammonium phosphate; processing conditions.

Grants and funding

The work was financially supported by the Open Fund of Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province (JBGS009) and the Key Laboratory of Plant Fiber Functional Materials, National Forestry and Grassland Administration (2022KFJJ04).