Flame Retardant and Antistatic Properties of Foamed Wood-plastic Composite Materials
Domestic and foreign scholars have done a lot of research on solving the flame retardant and antistatic aspects of WPC, but there are few reports on the antistatic, flame retardant and smoke suppression properties of foamed wood plastic composites (FWPC).Therefore, this study uses azodicarbonamide (AC) as the foaming agent, zinc oxide (ZnO) as the initiator, and nanometer calcium carbonate (Nano-CaCO3) as the nucleating agent.The foaming process is used to effectively reduce the density of salix/PE-HD composite material and reduce its own weight.At the same time, the cells can effectively prevent crack expansion and improve the problem of poor toughness of composite materials.In addition, nano-conductive carbon black (Nano-CB) and synergistic flame retardant APP/ZB were added to the FWPC system to prepare a flame-retardant and antistatic salix/PE-HD foam composite material.By compounding APP and ZB as a synergistic flame retardant, FWPC can maintain its mechanical properties.At the same time, it has good flame retardant and smoke suppression properties, and realizes the functionalization and high-value goals of wood-plastic composite materials, which has important practical significance for broadening the application of composite materials.
When the flame retardant addition amount is 20%, the impact of different mass ratios of APP and ZB on the mechanical properties, combustion properties, flame retardant and smoke suppression properties of FWPC,TG and SEM were used to conduct thermogravimetric analysis and microstructural analysis of the carbon layer after combustion on FWPC. The results are as follows.
(1) The combination of flame retardant APP and ZB has a good synergistic effect in improving the flame retardant and smoke suppression properties of salix/PE-HD foamed wood-plastic composite materials.The flame retardant and smoke suppression effect is better than that of APP and ZB used alone, but the mechanical properties of FWPC are reduced. When the APP/ZB mass ratio is 4:1, the comprehensive performance of FWPC is better.
(2) When the mass ratio of the synergistic flame retardant APP/ZB is 4:1, the oxygen index reaches 27.3%, reaching the flame retardant level. Compared with adding the flame retardant ZB alone, the flammable material is transformed into a flame retardant material;It has obvious flame retardant and smoke suppression effects on FWPC. The total smoke release, peak CO production rate and average CO production rate are 9.6m2, 0.0329kg/kg and 0.1014kg/kg respectively.Compared with adding APP alone, they were reduced by 11.93%, 80.6% and 49.3% respectively, indicating better flame retardant and smoke suppression effects.
(3) TG analysis shows that the thermal stability of the composite material is improved when the flame retardants APP, ZB and APP/ZB (ratio 4:1) are added respectively compared to the case where no flame retardant is added.Moreover, when APP and ZB are added together, the weight loss onset temperature decreases by 23.35°C, the total mass fraction decreases by 26.63%, and the thermal stability performance is optimal.
(4) SEM analysis shows that: When APP and ZB are used in combination, they give full play to their respective advantages in different flame retardant mechanisms and cooperate with each other.The surface of FWPC forms a dense protective layer and distributes a large number of carbon layers with a lamellar structure. The barrier layer is uneven, which has an obvious composite effect on the material's flame retardancy and smoke suppression, and the flame retardant and smoke suppression properties of the composite material are improved.
