Study On The Preparation And Properties Of Flame-Retardant Anion Polyester Fibers

With the increasing emphasis on renewable energy,recycled polyethylene terephthalate?RPET?fibers have been widely used.The application of recycled polyester fiber products covers the fields of non-woven fabrics,home textiles,automobiles and so on.However,due to the lack of attention to product development,the profit margin brought about by the production of recycled polyester is constantly being reduced.Therefore,the development of fiber products with various functions and the increase in the added value of recycled polyester?RPET?fibers have gradually been concerned.This article selected the phosphorus-containing organophosphorus flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivative?DOPO-FT?and the inorganic nanomaterial ceria.?GeO₂?as a modification additive.The RPET/DOPO-FT masterbatch and RPET/GeO₂ masterbatch were prepared by melt blending method.Flame retardant recycled polyester fiber and flame retardant negative ion recycled polyester fiber were prepared by masterbatch spinning.Then the fiber was analyzed for melting and crystallization,mechanical properties,thermal stability,flame retardancy and negative ion performance.The main conclusions were as follows:?1?RPET/DOPO-FT flame retardant fibers were prepared by the masterbatch method.Differential scanning calorimetry results showed that DOPO-FT had an effect on the melting and crystallization behavior of RPET,played an obvious role as a nucleating agent.After added DOPO-FT,the melting temperature of RPET slightly increased,and the crystallinity increased at first and then decreased.When the content of DOPO-FT was 6 wt%,the crystallinity X_c of RPET was 39.95%and the crystallization temperature increased,while the crystallinity?T decreased,suggesting that the addition of DOPO-FT promoted the crystallization,improved the crystallization rate and contributed to heterogeneous nucleation.When DOPO-FT was further added,the influence of clusters became larger,and the crystallinity and crystallization rate of RPET decreased.When the DOPO-FT content was 6 wt%,the fiber strength reached up to 3.2 cN/dtex.The results of thermal stability analysis proved that DOPO-FT could improve the thermal stability of RPET.When DOPO-FT content was 10 wt%,the maximum residual carbon content at 700?reached 16.68%.The results of the flame retardancy analysis demonstrated that with the addition of DOPO-FT,the limiting oxygen index value was significantly increased and could come up to 27.3%when the content was 10 wt%.The horizontal combustion level could reach B₁ level and the vertical combustion level could reach V-0 level.Scanning electron microscopy and Raman spectrogram analysis of the carbon layer showed that the addition of DOPO-FT could significantly reduce the number of pores and effectively promote the formation of the carbon layer.?2?RPET/DOPO-FT/GeO₂ flame retardant anion fibers were prepared by the masterbatch method.Differential scanning calorimetry results proved that the addition of GeO₂ reduced the crystallization rate of RPET and decreased the crystallinity X_c.With the increase of GeO₂ content,the mechanical strength of the fiber was slightly reduced.The TGA results showed that the amount of residual carbon could increase significantly if GeO₂ was added.When the content of GeO₂ was0.25 wt%,the maximum residual carbon content at 700?could reach 17.08%,indicating that GeO₂had a significant synergistic flame retardant effect at high temperature.The results of flame retardancy analysis illustrated that when the content of GeO₂ was 0.25 wt%,the maximum limit oxygen index value could come up to 35.7%.The horizontal combustion level could reach B1 level,and the vertical combustion level could reach V-0 level.In addition,the number of droplets in the combustion process was significantly decreased.Scanning electron microscopy and Raman spectrogram analysis of the carbon layer showed that after added GeO₂ particles,the carbon layer became dense and flat,and the degree of graphitization increased.The P-Ge system had a significant synergistic flame retardant effect.Pyrolysis gas chromatography-mass spectrometry?Py-GC-MS?analysis showed that the main products of degradation at 450?were acetaldehyde and benzoic acid,which implied that the main mechanisms of degradation of the three fibers were the same,but the degree was different.The amount of dibenzofuran(C₁₂H₈O)in the cracked product did not increase,indicating that the flame retardancy of DOPO-FT was due to the fact that P element could promote the dehydration and carbon formation of the polymer matrix,and the carbon layer could prevent mutual exchange of heat insulation and transfer of oxygen,which formed condensed phase flame retardant mechanism.The results of negative ion performance analysis of fabrics illustrated that with the increase of GeO₂ content,the number of negative ions increaseed gradually.When GeO₂content was only 0.08 wt%,the number of negative ions generated could reach 1300/cm³.