The Synergistic Flame Retardant Effect Of Activated Carbon And Molybdenum Compounds In Flexible Poly (Vinyl Chloride)

Polyvinyl chloride?PVC?is a kind of common thermoplastics,which widely used in our life due to its unique properties.Due to the mass fraction of chlorine in pure PVC is56.8%,makes it excellent flame retardant properties.But in order to make the PVC materials easy to process,a large number of flammable plasticizers were added and deteriorated its flame retardancy during burning.So improving the flame retardant and smoke suppression effects for PVC have very important significance.But after joining the traditional flame retardant,although improved the flame retardant and smoke suppression performances of materials,but also worsen the materials'mechanical performance,which limited the application of materials.So how to choose efficient flame retardants and how to improve the mechanical performances for PVC materials have became the key problems for the researches of flame retardant.Firstly the raw materials of activated carbon?AC?and molybdenum trioxide?MoO₃?have been characterized and applied to PVC.The flame retardant and smoke suppression property,thermal stability and carbon residue of PVC composite materials were analyzed;Then the phosphomolybdic acid ionic liquid?PIL?,prepared by MoO₃,H₃PO₄ and ionic liquid?IL?,was characterized and then used in PVC with AC,the flame retardant and smoke suppression performances,thermal stability and mechanical properties of PVC composite materials were studied.Specific work is as follows:The first part:the synergistic flame retardant effect of AC and MoO₃?1?The raw materials'characterization of AC and MoO₃ showed:AC had irregular shape and different particle size;mainly contained the elements such as carbon,oxygen,calcium,iron;specific surface area was 335.15 m²/g;had the very high thermal stability.MoO₃ showed nano flake of about 10×4×0.5?m³,and also very stable.?2?The scanning electron microscope?SEM?of PVC composites'fracture surface results showed that the AC and MoO₃ were evenly dispersed in PVC continuous phase.Cone calorimeter test?CCT?results showed that the peak heat release rate?PHRR?and smoke release rate peak?PSPR?values of PVC/AC/MoO₃ were the lowest of 174 kW/m²and 0.147 m²/s,respectively.Which were reduced by 47.3%and 59.9%compared with pure PVC,respectively.?3?The thermogravimetric analysis?TG-DTG?results showed that AC can promote early crosslinking of PVC,and the gel content of PVC/AC was as high as 73.9%.The thermogravimetric and fourier transformed infrared analysis?TG-IR?results showed that MoO₃ can promote PVC to release a large amounts of HCl in a short time,so that the PVC/MoO₃ has certain self-extinguishing effect.Moreover,Raman analysis results showed that the crystallite size of carbon residue for PVC/MoO₃ was the smallest,Which meaned the highest degree of graphitization.Therefore,AC and MoO₃ has a certain synergy effect,Which made the most carbon residue of PVC/AC/MoO₃,So flame retardant and smoke suppression performances of PVC/AC/MoO₃ is the excellent.The second part:the synergistic flame retardant effect of AC and PIL.?1?The phosphomolybdic acid?PMoA?was prepared by MoO₃ and H₃PO₄,and then reacted with 1-butyl-3-methy limidazolium tetrafluoroborate?IL4?and 1-hexadecyl-3-methy limidazolium chloride?IL16?to prepare phosphomolbdic 1-butyl-3-methylimidazolium?PIL4?and phosphomolbdic 1-hexadecy-3-methylimidazolium?PIL16?.SEM,FTIR and TG-DTG results showed that the target products were synthesized,and the thermal stability of PIL4 was higher than PIL16.?2?The test results of LOI showed that PVC-5 sample has the highest LOI value,Which verified the flame retardancy of PIL4 is higher than PIL16.The CCT results showed that PVC-3 has the lowest PHRR,total heat release?THR?,the average mass loss rate?Av-MLR?and the average effective heat of combustion?Av-EHC?values,and the lowest PSPR,total smoke release?TSP?and the average of extinction area?Av-SEA?values.Therefore,When the mass ratio of AC and PIL4 is 8:2,the PVC sample performed the optimal performance.Due to the presence of long alkyl chain in PIL16,the phosphorus and molybdenum content of PIL16 was lower than the phosphorus and molybdenum content in PIL4 in the same quality,thus the performance of the flame retardant and smoke suppression of PVC-7 slightly worse than PVC-3.?3?The mechanical performance test results of PVC samples showed that with the increase of PIL4 and PIL16,the elongations at break and impact strengths of PVC materials increased.The elongation at break and impact strength of PVC-10 and PVC-11 samples were 504%,12.25 kJ/m² and 511%,10.76 kJ/m².The elongation at break of the two samples were comparable to pure PVC,but the impact strength of the two samples were increased by34.5%and 34.5%respectively,compared with pure PVC.Therefore,PVC-10 and PVC-11samples reduced the cost,and at the same time have excellent flame retardant and smoke suppression performance and mechanical performance.