通过沉淀包覆法制备不同包覆比例的植酸锡包覆羟基锡酸锌 (tin phytate coated zinc hydroxystannate, ZHS@Sn-Phyt) 复合协效阻燃剂, 并应用在软质聚氯乙烯 (polyvinyl chloride, PVC) 中. 采用 X 射线衍射 (X-ray diffraction, XRD)、扫描电子显微镜 (scanning electron microscope, SEM)、傅里叶变换红外光谱(Fourier transform infrared spectroscopy, FTIR)、X 射线光电子能谱 (X-ray photoelectron spectroscopy, XPS) 和热重分析 (thermo-gravimetric analysis, TGA) 对包覆结构进行分析表征, 同时对 PVC 复合材料进行极限氧指数 (limiting oxygen indexand, LOI)、锥形量热 (cone calorimetry, CONE) 和力学性能测试. 结果表明: 在羟基锡酸锌 (zinc hydroxystannate, ZHS) 表面和植酸锡 (tin phytate, Sn-Phyt) 包覆层之间以 Sn—O—P—O—Zn 离子键的形式形成稳定的包覆结构; 当复合阻燃剂中 Sn-Phyt∶ZHS 质量比为 1∶9 时, 对 PVC 的阻燃效果最佳, 表现出较好的协同阻燃作用, LOI 比加入相同份数ZHS 的PVC 样品增加了1.6%, 热释放速率峰值和热释放总量分别降低了18.9% 和31.7%, 残炭率提高了6.1%, 烟释放总量相差不大, 拉伸强度和断裂伸长率分别为26.79 MPa 和 296.5%, 也均优于后者. 因此, 制备了一种高效绿色阻燃剂用以阻燃 PVC, 所制备的磷-锡协效阻燃剂具有绿色环保和工艺简单的优点.
This article presents a synthetic method for tin phytate-coated zinc hydrox-ystannate (ZHS@Sn-Phyt) particles with different ratios, which were incorporated into soft polyvinyl chloride (PVC) as a composite synergistic flame retardant. The synthe-sized ZHS@Sn-Phyt particles were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results revealed that a stable coating structure was formed in the form of Sn—O—P—O—Zn ionic bonds at the interface between the zinc hydroxystannate (ZHS) surface and the tin phytate (Sn-Phyt) coating layer. The PVC composites were evaluated through limiting oxygen index (LOI), cone calorimetry, and mechanical studies. When the mass ratio of ZHS@Sn-Phyt in the flame retardant was 1∶9, the best flame retardant properties of PVC were achieved, indicating that combining phosphorus and tin results in a better synergistic flame retardant effect. The LOI of the PVC/ZHS@Sn-Phyt composite was 1.6% higher than that of the PVC composite with only ZHS (without the Sn-Phyt coating). Moreover, the peak heat release rate and total heat release decreased by 18.9% and 31.7%, respectively. In addition, the carbon residue rate increased by 6.1% and the total smoke release of PVC/ZHS@Sn-Phyt and PVC/ZHS were similar. Both the tensile strength and the elongation at break of PVC/ZHS@Sn-Phyt were also better than those of PVC/ZHS at 26.79 MPa and 296.5%, respectively. Thus, this study provides a method for preparing efficient and green flame retardants for PVC. The phosphorus/tin-based synergistic flame retardant prepared by our method has the advan-tageous characteristics of ecofriendliness and simplicity of the preparation process.
