The Research On Flame Retardant Property Of Polypropylene/Flame Retardant Wood Flour Composites

Polypropylene (PP) based wood-plastic composite (WPC) is a high performance green composite materials with durable, easy processing, anti-aging, recyclable and other characteristics. It has been widely used in Construction, Automotive Interiors, Product Packaging and other fields. PP-based WPC is easy to burn, but most of its application fields require materials with good flame retardant. Thus giving WPC good flame retardant property is required in the application development.The main method of preparing flame-retardant WPC is adding all kinds of flame retardants in it. This method has the disadvantages of large adding amount, various interfacial interactions, and poor mechanical properties. In this paper, choosing wood retardant FRW and modifying wood flour (WF) to prepare flame-retardant wood flour (FRWF). With FRWF instead of WF added into PP prepares flame-retardant WPC. Therefore, in first chapter, the optimal preparation of FRWF is explored.5 g WF is mixed with 20 mL 10 wt% FRW fire retardant liquid,30 min under vacuum impregnation at 80 ?, drying at 80?100 ?. Compared with WF, the moisture absorption of FRWF in the air becomes weaker with the increasing of drug loading of FRWF. This feather will improve the performance of WPC.The second chapter studies the combustion effect of FRWF in WPC (PP/FRWF). We find that FRWF is easy to be carbonized when burning, but it has little effect on PP. Thus carbonized particles of FRWF dripping with molten PP, it does not form a solid char layer structure. So, by adding Nickel formate (NF), Nickel oxide, fumed silica, boron phosphate and modified sepiolite+bismuth trioxide synergist into PP/FRWF, enhance the strength of the carbon layer and weaken PP droplet effect. Test results show that NF has the strongest synergistic flame retardance, but PP droplet phenomenon in PP/FRWF /NF, does not improve significantly. It indicates that adding FRWF and NF is not enough to achieve good flame retardant performance.The third chapter uses PP/APP/PER for reference. From the theoretical analysis and optimization of content PP/FRWF, perfecting formula of PP/FRWF and enhancing flame-retardant properties of PP matrix. Weakening droplet effect and improving the flame retardant properties of WPC. While m(PP):m(compatibility agent):m(FRWF): m(APP)= 100:6:40:11.73, m(PP):m(compatibility agent):m(FRWF):m(APP) = 100:6: 40:9.591, the material has the best flame retardant. After adding 3.219 phr synergists NF, flame retardant propertiy of WPC is further improved.The fourth chapter, studies the the decomposition kinetics of the material, exploring a variety of measures from the microscopic point of flame retardant effect. With FRWF instead WF added into PP, PP/FRWF can produce more carbon residue at the time of the pyrolysis. But the apparent activation energy of PP/FRWF is lower than PP/WFs', and frequency factor is also reduced. This indicates that FRWF instead of WF makes the WPC easier to break down, but the decomposition rate decreases. Adding APP into PP/ FRWF increases the thermal stability of the char layer in the first stage of weightlessness. But the apparent activation energy and frequency factor of PP/FRWF/APP reduced, compared with PP/FRWF. As compared with PP/FRWF/APP, adding NF makes the largest thermal weight loss rate reduced, but the apparent activation energy and frequency factor of PP/FRWF/APP/NF is higher than PP/FRWF/APP's. This indicates that adding NF makes the material more difficult pyrolyzed, and its thermal stability is improved. The CONE results show that FRWF series have a longer time to ignition, lower heat release, less smoke and toxic gas emissions than WF series'. So flame retardant property of FRWF series is better than WF series', which means a better flame retardant property of WPC can be prepared by adding FRWF.Finally, according to the CONE test results, to evaluate material fire behavior by AHP. It is found that FRWF series has the lowest level of fire danger, wherein PP/ FRWF/APP/NF has the most significant effect. So by FRWF instead of WF preparing flame-retardant WPC can reduce the risk of fire, and improve anti-fire capability of WPC.