Synthesis of microencapsulated zinc stannate and its application in flame-retardant poly(vinyl chloride) membrane material
Summary The novel core-shell magnesium dihydroxide (MDH)/zinc stannate (ZS) and melamine-formaldehyde (MF) resin/MDH/ZS microcapsules were prepared. Their structures were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy analysis techniques, then its flame-retardant application in poly(vinyl chloride) (PVC) composites. The PVC composites were investigated by the limited oxygen index, smoke density, vertical burning test (UL-94), cone calorimeter test, scanning electron microscopy, and thermogravimetric analysis. When directly exposed to flame, PVC generated a high-density char layer, giving PVC a self-extinguishing property. Furthermore, when the mass ratio of MDH/ZS and MF/MDH/ZS microcapsules were 2/8 and 10/2/8 with 16 wt% loading, the results showed that the limited oxygen index value reached 29% and 33%, and the smoke density value reached 51% and 41%. Thus, the microencapsulated ZS could greatly suppress the generation of the flame and smoke during combustion, showing potential applications as multifunctional advanced composites. Two aspects of this manuscript will make it interesting to general readers of Fire and Materials. The magnesium dihydroxide (MDH)/zinc stannate (ZS) microcapsule was firstly prepared via chemical deposition method, and then melamine-formaldehyde (MF) resin/MDH/ZS microcapsule was secondly prepared. The smoke density of poly(vinyl chloride) (PVC)/MDH/ZS microcapsule and PVC/MF/MDH/ZS microcapsule composites were less than half of the neat PVC. With the addition of the 16 wt% of MDH/ZS or MF/MDH/ZS microcapsules into PVC, the limited oxygen index value of PVC composites achieved a significantly high limited oxygen index value at 29%, 33%, and the smoke density value of PVC reached 51%, 41%, respectively. They are V-0 rating in UL-94 test. The results indicated that MDH/ZS and MF/MDH/ZS microcapsules behaved as an environmental friendly flame retardant and smoke suppressant. Thus, this study demonstrated the great potentials of the intrinsically flame-retardant MDH/ZS and MF/MDH/ZS microcapsules in the application of high performance matrix resin and composite material.
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