Zaihang Zheng

Preparation of microencapsulated ammonium polyphosphate with carbon source- and blowing agent-containing shell and its flame retardance in polypropylene

In this paper, a novel and facile method was carried out to microencapsulate ammonium polyphosphate (APP) via two-step surface polymerization process, which introduces the carbon source and blowing agent into the microcapsules simultaneously. The chemical composition of microencapsulated APP (MAPP) was confirmed by fourier infrared spectra (FTIR). The surface morphology and thermal behavior of APP and MAPP were investigated by scanning electron microscope (SEM) and thermogravimetric analysis (TGA), respectively. Additionally, transmission electron microscopy (TEM) demonstrates that MAPP particles possess the obvious “core/shell-like” structure. Compared with APP, the water solubility of MAPP greatly decreases that can improve the water resistance of MAPP in polymer materials when exposed to water. Moreover, the flame retardant properties of polypropylene (PP) compositing with MAPP were systematically researched by limiting oxygen index (LOI), vertical burning tests (UL-94) and cone calorimeter. The results show the flame retardant properties of PP composites are enhanced by combining MAPP than that of APP. Besides, the water resistance of PP/MAPP is also enhanced. And the char residue of PP composites after combustion was analyzed by FTIR and X-ray photoelectron spectroscopy (XPS) spectra. Based on these facts, a possible flame retardant mechanism of MAPP in PP composites was proposed.

Synthesis and surface properties of semi-interpenetrating fluorine-containing polyacrylate and epoxy resin networks

Semi-interpenetrating polymer networks (Semi-IPNs) based on fluorine-containing polyacrylate and epoxy resin were synthesized by the simultaneous polymerization of fluorine-containing acrylate and epoxy resin. Fourier transform infrared (FTIR) spectrometry and X-ray photoelectron spectroscopy (XPS) analyses proved that the fluorine-containing groups have been introduced into Semi-IPNs successfully. In addition, XPS analysis intuitively showed that the fluorine content of the film-air interface of the interpenetrating fluorine-containing polyacrylate and epoxy resin networks (FPAER-SIPNs) film was much higher than that of the film-glass interface. It is noted that the introduction of fluorine-containing groups significantly improved the hydrophobic property of polymer networks. Moreover, when the fluorine content increased, the contact angle of water on FPAER-SIPNs film was increased obviously and the water uptake was decreased gradually. These results indicated that introducing fluorine-containing groups to SIPNs has potential advantage for improving the surface properties of epoxy resin.