Study On Preparation And Properties Of Castor Oil Based Flame Retardant Polyurethane

Polyurethane(PU) is an organic polymeric material and has been widely used in many fields, such as aerospace, automotive, electronics, construction insulation, light industry, chemical industry and national defense due to its excellent performance. The conventional PU materials were prepared by petroleum-based polyether/polyester polyols and isocyanate. With the increasing depletion of petroleum/petrochemical resources and serious environmental pollution, renewable biomass resource has being gotten the attention and development. Castor oil(CO) and its derivatives have been widely used in many fields such as elastomer, adhesives and coatings due to its extensive sources, renewable and cheap prices. Castor oil and its derivatives contained hydroxyl, ester, double bond and carboxyl functional groups, which can be modified as hydroxyl groups through esterification, hydrolysis and epoxidation reaction, and then react with isocyanate for polyurethane materials. The application and development of castor oil and its derivatives is of great significance to the sustainable development of the polyurethane material industry. However, bio-based polyurethane material is highly flammable and its oxygen index(LOI) is low, this seriously limits its wide application. Therefore, the research of flame retardant bio-based polyurethane material has been a significant issue. A review on the flame retardant mechanism and the research progress of polymer(polyurethane) was carried out, the additive flame retardants have some disadvantages such as low flame retardant efficiency and the decrease of mechanical properties. Therefore, in this paper, APP/AHP flame retardant system, P-N Containing polyurethane prepolymer and castor oil/ricinoleic acid based flame retardant polyether polyol were prepared and used to prepare polyurethane materials, which provide some new ways to solve the mentioned problems. On the basis, the thermal degradation mechanism and flame retardant mechanism were studied. The main research contents and results are as follows:1. Based on castor oil(CO), the flame retardant polyurethane sealant(FRPUS) with ammonium polyphosphate(APP) and aluminum phosphate(AHP) was prepared. The effects of APP/AHP on the flame retardancy, thermal stability and the mechanical properties of PUS were investigated; the gas pyrolysis products were investigated by TGA-FTIR, TGA-MS and Py-GS-MS, the residual were investigated by FTIR, SEM and XPS, the thermal degradation mechanism and flame retardant mechanism were explored by the above methods. The results showed that when the mass ratio of APP to AHP was 5:1, and the total content of APP/AHP was 50 %, the limiting oxygen index(LOI) of FRPUS reached 35.1 %, which was increased by 74.6 %, the peak heat release rate(pHRR), total heat release(THR) of FRPUS were reduced by 82.3 % and 68.8 %. APP/AHP flame retardant composite enhanced the thermal stability and the quality of char layer of FRPUS at high temperature. The TGA-FTIR and TGA-MS results showed that APP/AHP flame retardant composite can effectively reduce the combustible gas amount, and produce non combustible gas and phosphorus free radical scavenger. TGA and thermal degradation kinetics showed that APP/AHP flame retardant composite enhanced the thermal stability of FRPUS. Combined with the results of residual carbon analysis, it was showed that the flame retardant mechanism of APP/AHP system was the combination of gas phase and condensed phase flame retardant mechanism.2. A novel phosphorus and nitrogen-containing flame retardant polyurethane prepolymer(FRPUP) was successfully synthesized and characterized by FTIR, 1H NMR and 31 P NMR. The flame retardant polyurethane sealants(FRPUS) were prepared by curing FRPUP with castor oil(CO). The thermal degradation behavior and flame retardant behavior of FRPUS were investigated. The results showed that FRPUP could increase the LOI of FRPUS to 23.0 %, which was increased by 20.4 %; the pHRR and THR of FRPUS were reduced by 48.0 % and 14.0 %. FRPUP enhanced the thermal decomposition temperature and char residue, decreased the thermal decomposition rate. Combined with the results of residual carbon analysis, the flame retardant mechanism of FRPUP was the combination of gas phase and condensed phase flame retardant mechanism. FRPUP reduced the hardness of FRPUS and the tensile strength, increased the elongation at break.3. A novel phosphorus and nitrogen- containing flame retardant polyols(FRPE) was successfully synthesized by ricinoleic acid(RA) with phenyl dichlorophosphate(PDCP) and characterized by FTIR, 1H NMR and 13 C NMR. The results showed that FRPE reduced the pHRR and THR of FRPE/PUS, which were reduced by 52.0 % and 11.0 %, increased the LOI of FRPE/PUS to 24.1 %, which was increased by 31.7 %. The thermal degradation process of FRPE/PUS were investigated by TGA、TGA-FTIR and TGA-MS. The results showed that FRPE enhanced the thermal decomposition temperature and char residue, decreased the thermal decomposition rate; the types of thermal degradation gas products were not change, the release time and amount of gaseous products were change. Combined with the FTIR、SEM �'�XPS analysis results of residual carbon, it was showed that the flame retardant mechanism of FRPE was the combination of gas phase and condensed phase flame retardant mechanism. FRPE can enhance the hardness, tensile strength and storage modulus of PUS.4. A novel phosphorus and nitrogen- containing flame retardant polyols(FRPE) was successfully synthesized by castor oil(CO) with DOPO and characterized by FTIR, 1H NMR and 13 C NMR. The flame retardant polyurethane foam(PUF) was prepared FRPE and flame retardant dibasic alcohol(BHAPE) with isocyanate. The results showed that the optimal mass ratio of FRPE to BHAPE was 6:4. FRPE/BHAPE increased the LOI of PUF to 25.4 %, which was increased by 30.3 %. FRPE/BHAPE significantly reduced the HRR and THR of PUF and improved the thermal stability of PUF. Through the analysis of residual carbon by FTIR, XPS and SEM and the analysis of gas phase pyrolysis products by TGA-FTIR, TGA-MS, the flame retardant mechanism of FRPUF was the combination of gas phase and condensed phase flame retardant mechanism.