Effect of single- and double-layer encapsulated ZnSnO3 on flame retardancy and smoke suppression properties of poly(vinyl chloride) membrane composites

The influence of single layer ZnSnO3@Mg(OH)2 microcapsule and double layer ZnSnO3@Mg(OH)2@melamine formaldehyde resin(MF) microcapsule on the flame retardancy and smoke suppression properties of polyvinyl chloride(PVC) membranes were analyzed by limiting oxygen index(LOI), horizontal and vertical burning test, smoke density(SDR) test, SEM and TG instrument. The results show that ZnSnO3@Mg(OH)2 and ZnSnO3@Mg(OH)2@MF microcapsules can effectively enhance the flame retardancy, smoke suppression, anti-dripping and self-extinguishing properties of PVC membranes. The LOI value of ZnSnO3@Mg(OH)2/PVC and ZnSnO3@Mg(OH)2@MF/PVC membrane composites obviously increases, with increasing the content of the microcapsules. However, when the content of the microcapsules increases, the smoke density and self-extinguishing time of ZnSnO3@Mg(OH)2/PVC and ZnSnO3@Mg(OH)2@MF/PVC membrane composites decreases. The TG results show that the initial degradation temperature of ZnSnO3@Mg(OH)2/PVC and ZnSnO3@Mg(OH)2@MF/PVC membrane composites move to low temperature and the amount of residual carbon increases with the content of the microcapsules. The SEM micrographs of residual carbon of ZnSnO3@Mg(OH)2/PVC and ZnSnO3@Mg(OH)2@MF/PVC membrane composites show that the addition of the microcapsules effectively promotes the form compact carbon layer of ZnSnO3@Mg(OH)2/PVC and ZnSnO3@Mg(OH)2@MF/PVC membrane composites during burning, which not only can inhibit oxygen and heat to go into the PVC bulk, but also inhibit combustion gases to go out the PVC bulk. SEM and tensile strength results show that double layer microcapsule can availably improve the dispersion and compatibility between inorganic particles and PVC matrix. © 2017, Chinese Society for Composite Materials. All right reserved.