Preparation And Performance Of Cellulose Based Flame Retardant Materials

Cellulose,the natural renewable resources with the most memory space on the earth,is always used in the field of household supplies,textile and clothes,aviation and military,food packing,et al as well as replacing some synthetic resin and fibers for the imminent shortage of fossil fuels,which are all because of its characters that are good biocompatibility,fine biodegradability and well moisture absorbing and releasing behavior,et al.It is considered to be the most promising substitution of synthetic fibers,synthetic resins and other petrochemical materials.As a result,improving the flame retardant of cellulose materials with environmental and efficient fire retardant is one of the most important things on regenerated cellulose based functional materials at present.In this paper,the author prepared the cellulose based flame retardant materials with self-prepared Mg/Al layered double hydroxides?Mg/Al-LDHs?,adjusted the anions during the layers of Mg/Al-LDHs via the response surface optimization method?RSM?,and investigated the combustibility by the means of limit oxygen index tests,vertical flammability tests and conical calorimetry tests.What's more,the flame-retardant mechanism was also researched by the TGA-FTIR analysis.The results were showed as following:?1?Preparation of Mg/Al-LDHs:Mg/Al-LDHs with CO₃^2-,HPO₄^2-,H₂PO₄^-and B₄O₇^2-were prepared by co-precipitation method and roasting recovery method,respectively,and controlled the intercalation anions of Mg/Al?H₂PO₄?-LDHs between the layers via the RSM.It is fined that different anions have different ability during interacting,and the CO₃^2-had the strongest intercalation ability,which had a fully ordered crystalline phase structure,HPO₄^2-and H₂PO₄^-are the second,the B₄O₇^2-is worst;What's more,Mg/Al?H₂PO₄?-LDHs had the best thermal stability,and Mg/Al?CO₃?-LDHs was the worst,the difference of their loss mass ratio was 12.38%.?2?Preparation and characterization of cellulose based flame retardant materials:The cellulose based flame retardant materials with different compositions were prepared with solution of NaOH/urea,crosslinking agent named N,N-methylenebisacrylamide?MBA?,and the main fire retardants—self-prepared Mg/Al-LDHs,and then investigated the thermal stability and mechanical property of which by thermogravimetric analysis,compression tests and dynamic thermal mechanical analysis.It was found that the thermal stability and mechanical properties were improved with the increased of LDHs,when Cellulose:Mg/Al?CO₃?-LDHs=1:0.6,the decomposition temperature of materials increased by more than 13°C,and occurred a case of turning ductile materials into ductile reinforce.What's more,the maximum compressive stress of materials with Mg/Al?CO₃?-LDHs and Mg/Al?H₂PO₄?-LDHs were twice and three times of the pure cellulose materials respectively,and the existing of sepiolite made it become softer.?3?Flame retardant properties and mechanism of cellulose based flame retardant materials:Combustion performance and flame retardant mechanism of the composite materials were investigated by limit oxygen index tests,vertical flammability tests,conical calorimetry tests and TGA-FTIR analysis.The study found that the fire resistance improved with the increased of LDHs,when cellulose:Mg/Al?CO₃?-LDHs=1:0.4,LOI>27,which were 59.11%higher than pure cellulose materials,in equal proportions,LOI of cellulose based flame retardant materials contain Mg/Al?H₂PO₄?-LDHs was going to be 63.00%.By the way,the existence of sepiolite resulted in prolonging the smoldering time.Furthermore,the heat release rate?HRR?reduced dramatically when there were LDHs and sepiolite,when cellulose:Mg/Al?CO₃?-LDHs=1:0.4,HRR went down from 144.80 k J/m² to68.23 kJ/m²,down by 52.88%,in equal properties,HRR of cellulose based flame retardant materials contain Mg/Al?H₂PO₄?-LDHs was 50.38 kJ/m²,down by 65.21%,by the way,the combustion process is free of smoke and tixic gases.According to the TCA-FTIR analysis,LDHs worked mainly in the gas phase when burning,also worked in solid phase.There are many approaches to improve the fire resistance of cellulose basic materials,for instance,blending boron-/nitrogen-/phosphorous-flame retardants with it or chemical modifying the cellulose with halogen like chlorine and bromine,but all these ways will affect the property of materials,what's more,it will release smoke and toxic gas once burn.The cellulose flame retardant materials were prepared with self-prepared Mg/Al-LDHs.The aim of improving flame retardant properties of cellulose based materials were achieved,it have good flame retardant,low HRR,excellent comprehensive performance et al,which were expected to be used in the field of environmentally friendly flame retardant thermal insulation panels et al.