Development Of Flame Retardant PA6 Fiber Modified With MCA Compound Flame Retardant System

Poly-amide 6?PA6?fiber has excellent strength,wear resistance,elastic recovery rate,hygroscopicity and other characteristics,making it a widely used synthetic fiber in the fields of wear,home decoration and industrial industries.With the sustainable development of social economy and science and technology and the improvement of people's living standard and quality,the demand for PA6 fiber in various fields is also increasing.The flame retardant performance of pure PA6 fiber is poor with its only 21-22%limit oxygen index and serious molten droplets during combustion,which greatly limits its application.Therefore,the research on the improvement of the flame retardant performance of PA6 fiber has gradually attracted the attention of more and more material R&D workers.In this paper,different compound flame retardant systems was selected to enhance the flame retardant performance of PA6 fiber.The thermal stability and synergistic flame retardant effect of the compound flame retardant system were investigated by studying the compound flame retardant PA6 resin,and then the composite flame-retardant system with good comprehensive performance would be spun through composite melt spinning to produce flame-retardant sheath-core composite fibers.First of all,melamine cyanurate?MCA?was chosen for this as the main flame retardant in this paper,which is a commonly used nitrogen flame retardant for PA6.In order to further improve its flame retardant efficiency,zinc sulfide?ZnS?,graphite-like carbon nitride?g-C₃N₄?and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide?DOPO?derivatives?DOPOY?were uesd with MCA compound to enhance the flame retardant performance of PA6 material synergistically.Then the above flame retardant systems were melt and blended by a twin screw extruder to prepare compound flame retardant PA6 resin chips,and the preparation of flame retardant PA6resin samples were completed by an injection molding machine;then the above chips would be characterized and analyzed its heat stability,and the samples would be characterized and analyzed its flame retardant performance.The results showed that each compound flame retardant system has little influence on the thermal stability of PA6.The thermogravimetic analysis results showed that the introduction of compound flame retardant increased the residual carbon content of PA6system,because the added flame retardant was helpful for flame retardant in the condensed phase.And the flame retardant effect was greatly improved compared with the pure sample.The limit oxygen index?LOI?value and vertical combustion results showed that the flame retardant PA6 material had reached the flame retardant level.Among them,the flame retardant system of MCA/DOPOY had the best flame retardant effect.When MCA added mass fraction was 3%and DOPOY added mass fraction was 3%,its LOI value can reach 30%,which had well flame retardant effect.Finally,the flame retardant PA6 resin chips with excellent comprehensive performance in the above were used as the sheath material,and the pure PA6 was used as the core material to prepare the flame retardant sheath-core composite fibers through composite melt spinning.Then the cross-sectional morphology,mechanical properties and flame retardant properties of fibers would be characterized and analyzed.The results showed that the mechanical properties of the flame-retardant PA6 sheath-core composite fibers were lower than the PA6 fibers,but the decrease was small,mainly due to the core layer of the fibers supporting the mechanical properties.The cross-sectional morphology of the sheath-core structure was obvious,and the fibers were arranged regularly;although the flame retardant performance of the flame retardant sheath-core composite PA6 fibers was lower than the resin materials,the flame retardant sheath-core composite PA6fibers still had well flame retardant effect.The fiber fabric of flame retardant system of MCA/DOPOY had the excellent flame retardant effect,and its LOI value can reach 29%.