磷-锡环保复合协效阻燃剂制备及其在PVC中的应用

Ecofriendly phosphorus-tin composite synergistic flame retardant:preparation and application in polyvinyl chloride

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 hydroxystannate(ZHS@Sn-Phyt)particles with different ratios,which were incorporated into soft polyvinyl chloride(PVC)as a composite synergistic flame retardant.The synthesized 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 advantageous characteristics of ecofriendliness and simplicity of the preparation process.