| Polypropylene?PP?is one of the widely used general-purpose plastics.It has the characteristics of good mechanical strength,low price,high transparency,etc.It is widely used in injection,film,pipe and other fields.But the oxygen index of PP is very low,only17%-19%,which greatly limits the wider application of PP.Brominated flame retardants are widely used in PP,but the risk of environmental pollution and carcinogenicity is high.Therefore,PP flame retardants are developing towards the trend of intumescent flame retardants.During the production of vitamin B6,a large amount of black paste industrial waste?The following was called black paste?was produced in the additive workshop.This solid waste had the characteristics of non-cross-linked macromolecular compounds and was difficult to burn.After burning,it would become charcoal and had potential as flame retardant.If the black paste was designed as flame retardant,it would not only solve the problem of industrial solid waste,but also bring certain economic value to it.Infrared spectrum showed the black paste contained amino,carboxyl,hydroxyl.However,the thermal stability of the black paste was not very high,and the residual carbon rate at 400°C for 10 minutes is only 51.4%.The black paste and melamine could be mixed and reacted in a solid-phase environment to form a solid block material and the reaction could be calculated that it can be done by the group contribution method.The use of melamine-modified black paste for flame retardation of PP could extend the flame burning time.The best modification ratio was that the mass ratio of black paste and melamine is 3:1.At this time,The residual carbon ratio was 66.26%when the flame retardant stayed at 400°C for 10min,which greatly improved the thermal stability of the black paste.In the flame retardant experiment with PP,the mass ratio of 4:6 flame retardant and PP burned for 75 mm was 252.02 s.The burning time compared to 86.27 s of pure PP was increased by 165.75 s,which proved that black paste had a certain flame-retardant effect.The experiment explored the optimal synthesis process conditions for intumescent flame retardants by using phosphoric acid,pentaerythritol and melamine as a system.Which was found the molar ratio of phosphoric acid,pentaerythritol and melamine was 2:1:2,and the optimum reaction temperature of phosphoric acid and pentaerythritol was 120°C for 4h.The flame retardant obtained at this condition.This flame retardant had higher expansion rate to 71.63 mL/g.In the study of the synergist for flame retardant,it was found that the addition of polyvinyl pyrrolidone can improve the phase of flame retardant and PP.However,it had an adverse effect on the flame retardant properties.Polyacrylic acid and resorcinol were good flame retardant synergists which could increase the expansion rate of flame retardant to 96.85 mL/g,making the flame retardant have higher flame-retardant efficiency.The reaction of black paste directly as a carbon source for flame retardant with pentaerythritol and phosphate showed that the expansion rate was not high,and the flame-retardant efficiency was low because the black paste contained few hydroxyl groups.Based on the weak acidity of black paste,a carbon source was prepared by black paste and triethanolamine reaction.When the mass ratio of black paste and triethanolamine was 2:1,the yield of carbon source was higher,reaching 68.74%.It was shown by infrared spectroscopy that the modified black paste exhibited characteristic absorption peaks at 1629 cm-1 and 1404 cm-1,and the carbonyl?C=O?characteristic absorption peak at 1730 cm-1 disappeared,It showed that black paste reacted with triethanolamine to form salt.When using triethanolamine modified black paste with polyphosphoric acid amine,melamine to compound into an intumescent flame retardant in a mass ratio of 15:10:6.3 to PP,and flame retardant with PP could be mixed in a mass fraction of 28/72.UL-94's flame retardancy rating of V-0,the flame retardant effect can be improved when resorcinol and polyacrylic acid are used as flame retardant synergists.The modified flame retardant with PP were based on improve flame retardant rating.In a mass ratio of 26/74 blend could achieve flame retardancy rating of UL-94 V-0.Black paste was a type of industrial solid waste.Modification of black paste into a macromolecular carbonizing agent was a resource recycling of solid waste. |
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