Prparation And Combustion Properties Of Flame Retard Ant Polyurethane Elastomer

Due to polyurethane elastomer (PUE) has high strength, high elasticity, high abrasion resitance and excellent low temperature performance, it is one of the widely used polymer materials. However, it is easy to burn and produces a large amount of smoke in combustion process, which leads a huge threat to people’s life and property security. Therefore, developing low-smoke non-halogen flame retardant PUE composite materials is an important research direction of functional flame retardant materials.Because of the problems existing in the traditional flame retardant PUE material, several typical flame retardant PUE compound materials have been prepared using modified expandable graphite (MEG), aluminum phosphate,50A type intumescent flame retardant and TCEP as flame retardants. The combustion performance, smoke properties and thermal stability were studied by cone calorimeter test (CCT), thermogravimetric (TG) analysis, electron microscopy (SEM) and TG-IR analysis. The main contents of this paper are showing in the following.(1) Combustion properties of flame retardant polyurethane based on modified expandable graphite (MEG) using situ polymerization method. The CCT results showed that MEG can improve the flame retardant and smoke suppression performance of PUE composites. The addition of 15% MEG makes the PHRR value of PUE materals decrease from 2384 kW/m2 to 103 kW/m2, and TSR value decrease from 836.7 m2/m2 to 23 m2/m2. The SEM test showed that MEG has a promoting effect on the formation of a dense carbon layer, and improve the structure of carbon layer. The TG results showed that MEG can improve the thermal stability of high temperature range, and the addition of 15% MEG makes the residue weight increase to 16.51wt% from 9.08wt%. TG-IR showed that MEG can greatly reduce the production of CO when it is incorporated in the composites.(2) The combustion performance, smoke properties and thermal stability of flame retardant PUE composites based on aluminium hypophosphite. The CCT results showed that aluminium hypophosphite has excellent flame retardant abilities and smoke suppression effect. The addition of 20% aluminium hypophosphite makes the PHRR value of PUE materals decrease from 2000 kW/m2 to 385 kW/m2, and the weight of char layer increase from 7% to 28%. The results of SEM showed that aluminium hypophosphite had a promoting effect on the formation of a dense carbon layer. The TG showed that aluminium hypophosphite has good ability of char formation and can improve the thermal stability of high temperature range. The formation of carbon layer reduces the release of the burning smoke of material, and increases nonflammable gases, such as CO2.(3) Synergistic flame retardant effects of iron series compounds (FeOOH, Fe and Fe2O3) with 50A in PUE composites. The results showed that 50A has excellent flame retardant abilities, good smoke suppression effect and good ability of char formation for PUE. The addition of 20% 50A makes the PHRR value of PUE decrease from 1950 kW/m2 to 282 kW/m2. What’s more, the synergistic flame retardant and smoke suppression effect of iron series compounds is remarkable. The CCT results suggested that iron series compounds can improve flame retardant and smoke suppression performance. The sample with 1.25% FeOOH and 8.75% 50A makes the PHRR value of PUE decreased from 725 kW/m2 (containing 10% 50A) to 398 kW/m2. The PHRR value of the sample with 0.625% Fe and 9.375% 50A is 552 kW/m2, and the PHRR value of sample with 1.25% Fe2O3 and 8.75% 50A is 383 kW/m2. The SEM and TG results showed that synergistic system can increase the weight of carbon layer and improve thermal stability for flame retardant PUE at high temperature range. TG-IR showed that the synergistic system can reduce the production of toxic gases with -NCO and -NHC=O functional groups.(4) Combustion performance and thermal degradation kinetics of flame retardant PUE composites based on TCEP. The CCT results showed that TCEP has good flame retardant effect for PUE. With the increase of TCEP, the peak heat release rate (PHRR) and total heat release (THR) values decrease. The addition of 20% TCEP makes the PHRR value of PUE decreased from 2940 kW/m2 to 1598 kW/m2. TG test results showed that 20% TCEP can improve the weight of char residue from 5.8wt% to 10.4wt% in the pyrolysis process.The kinetics parameters from Kissinger and Flynn-Wall-Ozawa (FWO) indicated that the sample containing TCEP has two decomposition stages, but pure PUE has only one decomposition stage. The results from Kissinger method showed the activation energy of pure PUE is 130 kJ/mol, and the activation energy valued of the sample with TCEP are 67.4 and 67.5 kJ/mol, respectively. And, the FWO results indicated the activation energy of pure PUE is 81 kJ/mol; the activation energy values of the sample containing TCEP are 48 and 58.7 kJ/mol, respectively.