Preparation And Fire Retardant Mechanism Of Recycled Paper Foaming Material With Silicon-aluminum Compounds

Recycled Paper Foaming Material (RPFM) which is made of old corrugated fiber is a kind of ecological and environmental compatibility materials by applying the principle of liquid frothing in pulp solution. However, the combustible waste paper fibers result in the flammability of RPFM which will affect its scope of application. Therefore, it is particularly important to improve the flame resistance property of RPFM and scientifically analysis its combustion characteristics as well as the mechanism.In order to investigate the effect of silica-alumina compounded system on fire resistance of RPFM, three factors including Al/SiO2 dosage, Al/SiO2 mole ratio and its adding patterns were optimized with orthogonal design and data analysis with range-method and variance-method. The results showed that addition ways affect the fire properties of RPFM most, Al/SiO2 mole ratio took the second place and Al/SiO2 dosage was the least. Only with the Al/SiO2 dosage of 900 mL, Al/SiO2 mole ratio of 1:1 and by adding aluminum sulfate solution first can the limited oxygen index (LOI) and char yield of RPFM reach the highest value of 32.0 and 53.51% in the investigation, respectively. Secondly, we used the following techniques and instruments in our analyses: X-ray Diffraction (XRD), Scanning Electron Microscopy-energy-dispersive X-ray (SEM-EDS), Thermal Analysis Techniques (TG-DSC) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The results included that silicon aluminum compounds did exist in RPFM. And SEM-EDS analysis showed that Al and Si evenly covered on the surface of the fiber by adding aluminum sulfate solution first and sodium silicate solution next. Thermal analysis showed that thermos-stability of RPFM improved significantly and the residual weight increased by 3.2 times to 37.99%. FTIR analysis indicated the pyrolysis process of RPFM decreases greatly.Finally, burning behavior of RPFM was evaluated by bench scale test with Cone calorimeter (CONE), including heat, smoke, charring, weight loss and features such as production of toxic products. Besides, SEM and EDS was conducted to further study the morphology of combustion residues and its elements distribution, respectively. The results included that the pk-HRR of RPFM reduced from 128 kW·m-2 to 67 kW·m-2 by modification,46.8% lower than the original sample. What is more, carbon yield rose from 23% to 42%, increase by 82.6%. The silicon-aluminum complexes can significantly reduce smoke-release and off-gas. In addition, the structure of the control group was completely collapsed, while the modified one still maintained an integrity structure. EDS analysis showed that the carbon content increased too, which also coincides with the char yield mentioned above.As a consequence, by reasonably designing and optimizing the silica-alumina compounded system, the flame retardant properties of RPFM can be enhanced, which also means reaching to the level B1 or level A2 in the national flame retardant material standard test.