The Phosphorus And Nitrogen Containing Flame Retardants Designed, And Investigated On The Preparation And Properties Of Its Polystyrene Composites

In this dissertation, to overcome the disadvantage of the easy flammability and high gas toxity of polystyrene during combustion, some new additive flame retardant, reactive flame retardant and layered nanomaterials have been designed and synthesized and applied into preparing flame retardant polystyrene and polystyrene nanocomposites, and then the thermal properties, flame retardancy and toxity of composites were investigated. Following the aspect of molecular design, the effective additive and reactive flame retardants were synthesized to incorporate to the polystyrene matix. Meanwhile, by the way of the nanotechnology, the layered OAHPi and FGO were synthesized to prepare the polystyrene nanocomposites. The thermal stability and flame retardancy of flame retardant polystyrene and polystyrene nanocomposites were investigated, and the flame retardant mechanism was illustrated. The specific research work of this dissertation was illustrated as follows:1. ODOMP and PEPA were traditional phosphorus-containing flame retardants in the previous research, which mainly functioned in the gas and condensed-phases. Two new phosphorus-containing additive flame retardants, BDMP and BPMP, were synthesized by esterifcation between ODOMP or PEPA and MDCP. The structure of BDMP and BPMP were confirmed by fourier transform infrared spectroscopy and nuclear magnetic resonance. Thermal gravity analysis results indicated that the thermal stability of BDMP and BPMP could meet the processing temperature of polystyrene. Although incorporating BDMP and BPMP into the polystyrene matrix, lowered the initial decomposition temperature of polystyrene, flame retardant polystyrene exhibited high flame retardancy and thermal stability compared to the pure polystyrene, such as increased the maxium decomposition temperature and char yields and delayed the process of thermal decopositon.2. To compare the flame retardant effects on additive and reactive flame retardant on the polystyrene matrix, two different phosphorous and nitrogen-containing reactive monomer, DMPMA and PMPMA, were firstly synthesized by esterification of ODOMP or PEPA, MDCP and NMA, and their structure were comfirmed using the analysis of FTIR and NMR. Then the monomers were incorporated into PS matrix by in situ bulk polymerization. The thermal stability and flame retardancy of copolymers were characterized by TGA, DSC, MCC, LOI, UL-94, TG-IR and Raman. The TGA results showed that the poly (St-co-DMPMA) and poly (St-co-PMPMA) had the lower initial decomposition temperature, the longer decomposition process, the higher maxium decomposition and char yield compared to the virgin polystyrene. The MCC results displayed that peak at heat release rate and total heat release decreased, and the combustion process delayed after incorporated flame retardant into the polystyrene matrix. Meanwhile the poly (St-co-PMPMA) peformed the higher flame retardant efficiency than the poly (St-co-DMPMA) in the same ratio, and the LOI value of PS-PMPMA30sample could reach to28.5%and passed the UL-94V-0rating. The TG-IR and Raman results showed that two flame retardant copolymers exhibited lower total gas release and higher graphitized char residual compared to the pure polystyrene, which indicated that they could improve the thermal stability and flame retardancy.3. Selected carbonization precursor (SPDPC), dimethylolpropionic acid and aluminium chloride to prepare organic aluminum phosphonate lamellar nanomaterials (OAHPi), the structure, morphology and thermal stability of OAHPi were characterized by using FTIR, NMR, XRD, XPS, SEM, TEM and TGA. Then PS-OAHPi nanocomposites were prepared by blending of OAHPi and polystyrene. The nanocomposites performed higher flame retardancy and thermal stability than polystyrene, such as delayed thermal degradation, increased the maximum decomposition temperature and the char yields. The TG-IR and Raman results showed that PS-OAHPi nanocomposite decreased the total overflow gas and increased the graphitization of char yields compared to the pure polystyrene.4. The A2B3type hyperbranched flame retardant functionized graphene oxide was synthesized successfully. A2was prepared by SPDCP and HEA, and aminoethyl piperazine was used as B3group. The structure, morphology and thermal stability of FGO were characterized by FTIR, NMR, XPS, SEM, TEM and TGA measurement. PS-FGO nanocomposite was synthesized through in situ polymerization. The thermal stability and flame retardancy of PS were improved significantly with few addition of FGO. Furthermore, incorporated FGO to PS matrix decreased the total overflow gas and the release of toxic gases and increased the graphitization of char residues. In conclusion, the fire safety of PS-FGO nanocomposites had been enhanced after FGO added.5. According to the ISO19700international standards, the smoke toxicity of PS-DMPMA and PS-PMPMA, PS-OAHPi and PS-FGO nanocomposites were tested by steady state tube furnace test platform. The results demonstrate that with the addtion of reacitve flame retardant DMPMA and PMPMA, incomplete combustion of flame retardant PS was improved, which decreased the release of CO2and increased the release of CO. The poor char forming ability of PS-DMPMA performed more smoke particles on combustion. However PS-PMPMA reduced the smoke particle because of the high char forming ability. The SSTF results showed that PS-OAHPi nanocomposites reduced the release of CO2and inhibited the smoke particle production, but increased the release of CO. As for PS-FGO nanocomposite, it showed lower release amount of CO, CO2and smoke particle. Meanwhile, RT-FTIR results showed that both the flame retardant polystyrene and polystyrene nanocomposites effectively increased polyphosphoric acid and cyclics compounds in the char, which improved the thermal stability and flame retardancy.