Study Of PC/ABS Alloy Flame Retarded By Bicyclic-cage Phosphate Siloxane

PC/ABS alloy, which is commomly used in modern industry, is made of polycarbonate and polystyrene- butadiene- acrylonitrile copolymer by blending process. PC/ABS alloy well combines the excellent mechanical and heat-resisting properties of PC with the processing and low-cost performances of ABS. PC/ABS alloy is widely used in car interior parts, business machines, communication equipments and household appliances.The limited oxygen index(LOI) of PC is 25% while LOI of ABS is 18%. At the thickness of 3.2mm, PC/ABS sample can not be rated V-2 in the vertical burning test. With the content of ABS increasing, the PC/ABS alloy becomes more flammable. Due to its high flame retardant requirement during application, it is necessary to prepare the flame-retardant PC/ABS alloy.This essay selecets PPSi as the halogen-free flame-retardant to prepare the flame-retardant PC/ABS(85:15) alloy(mass ratio) and the effect has been tested. 10wt% PPSi is shown to be effective in the PC/ABS alloy. In vertical burning test, flame-retardant PC/ABS can be rated V-0 at the thickness of 1.6mm, while the LOI increases to 32.7% from 21.8%. The result from TGA shows that PPSi promotes the carbon residue rate from 9.1% to 21.5%. SEM photos show the residue surface is distent and smooth while cellular structure is formed inside the residue. R(R=ID/IG)increases to 1.5 from 1.1 from Raman spectra, indicating higher graphitization and smaller pore size inside the residue. The tensile strength, flexural strength, Izod notched impact strength, MFR and Heat deformation temperature of PC/ABS with 12wt%PPSi are 51.7MPa, 87.8MPa, 40.0k J/m2, 16.7g/10 min and 114℃, respectively.PPSi is also chosen to prepare the flame-retardant PC/ABS(7:3) and the effect has been tested.18wt% PPSi is shown to be effective in the PC/ABS(7:3) alloy.In vertical burning test, flame-retardant PC/ABS can be rated V-0 at the thickness of 1.6mm, while the LOI increases to 31.5% from 20.6%. The result from TGA shows that PPSi promotes the carbon residue rate from 1.7% to 20.4%. According to the cone calorimeter test, PPSi is effective in reducing the heat and suppressing the smoke in the combustion process. The p HRR decreases from 487 k W/m2 to 369 k W/m2. The THR decreases from 199 MJ/m2 to 142 MJ/m2. TSR decreases from 19.5km2/m2 to 17.6km2/m2. SEM photos show the surface of residue is flat and smooth while cellular structure is formed inside the residue for the flame-retardant PC/ABS sample. In the thermal degradation or combustion process of PC/ABS/PPSi, Si element intends to move to the surface of the residue while the P element vapors in the form of PO· and HPO·. Raman spectra show that R increases to 1.9 from 1.2, indicating higher graphitization and smaller pore size inside the residue. PPSi takes effect in the flame retardancy in both condensed phase and vapor phase for PC/ABS. The tensile strength, flexural strength, Izod notched impact strength, MFR and heat deformation temperature of PC/ABS with 20wt%PPSi are 42.8MPa, 66.0MPa, 27.6k J/m2, 19.3g/10 min and 103℃, respectively.The combination of RDP and PPSi is used to prepare the flame-retardant PC/ABS(7:3) and the effect has been tested. 6wt% PPSi and 8wt%RDP is shown to be effective in the PC/ABS(7:3) alloy. In vertical burning test, flame-retardant PC/ABS can be rated V-0 at the thickness of 1.6mm, while the LOI increases to 31.7% from 20.6%. The result from TGA shows that PPSi promotes the carbon residue rate from 1.7% to 18.2%. According to the cone calorimeter test, PPSi is effective in reducing the heat. The p HRR decreases from 487 k W/m2 to 326 k W/m2. THR decreases from 199 MJ/m2 to 132 MJ/m2. SEM photos show a great amount of consistent bubbles inside the carbon residue of the flame-retardant PC/ABS, which can block the oxygen and heat. The tensile strength, flexural strength, Izod notched impact strength, MFR and heat deformation temperature of PC/ABS With 6wt%PPSi and 8wt%RDP are 33.2MPa, 48.7MPa, 24.6k J/m2, 23.4g/10 min and 95℃, respectively.Above all, PPSi can effectively improve the flame-retardant property of PC/ABS alloy and promote the residue rate. Although the PC/ABS(7:3) with total content of 14wt%(6wt%PPSi and 8wt%RDP)can be rated V-0 at the thickness of 1.6mm, the mechanical properties and heating resistance decrease a lot. The integrated property of PC/ABS flame-retarded by both PPSi and RDP is not as good as that flame-retarded by only PPSi.