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Study Of Flame-retardant PAN/PSA Blend Fibers

Posted on:2017-05-15Degree:MasterType:Thesis
Country:ChinaCandidate:X Y LiuFull Text:PDF
GTID:2271330503478364Subject:Materials engineering
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Due to its inflammability, polyacrylonitrile(PAN) is limited to be widely used as home textiles. Hence, methods on flame retardant modification of PAN have drawn great attentions. As one of the most environment friendly methods, blending modification still faces challenges like negative effect on spinning process with low-molecule retardants and instability in the blended yarn. Blend spinning with an inherent flame-retardant polymer can be one of the effective ways to solve the above problems. A new type of flame-retardant fiber obtained by co-solved spinning method was studied in collaboration with Shanghai Tanlon Fiber Co., Ltd. Solubility and compatibility of PAN/PSA blend in a solvent mixture, influence of blending ratio on rheology properties of PAN/PSA co-solution, flame-retardant properties of blended films and fibers were studied. Moreover, the effect of viscosity ratio between PAN and PSA on the blend’s morphology, mechanical properties and flame-retardant characters were also studied in order to optimize the blending ratio and flame-retardant properties.First, suitable solvents and solvent mixtures for preparing stable PAN/PSA blending solution were screened between DMAc and [BMIM]Cl. Moreover, its rheology properties were examined. The results based on macro-compatibility showed that phase separation appeared in PAN/PSA/DMAc solution but not in homogeneous PAN/PSA/[BMIM]Cl solution. Rheology results showed that by increasing the ratio of PSA, the non-Newtonian character and entanglement structure strengthened in PAN/PSA/[BMIM]Cl solution. Further, different blending ratios of PAN/PSA did not place an obvious effect on flow activation energy of blended solution.Next, blended films and fibers were prepared in different blending ratios and their morphologies and flammability were investigated. Studies on the flame retardant properties of PAN/PSA blends at ratio 7/3, 6/4, 5/5, 6/4 and 3/7 showed that self-extinguishing only occurred when the mass content of PSA was over 70wt% and self-extinguishing time(SET) was 4.56 s. Utilizing higher molecular weight PAN to prepare blend fibers at ratios of 5/5, 6/4 and 3/7, decreased the SET of blend samples compared to the same ratios in PAN/PSA composed of lower molecular weight PAN. Limited oxygen index(LOI) reached 26.2% when PSA content was 70wt%. SEM showed uneven surfaces in blend films and fluted surface in blend fiber in pure PSA sample and higher PSA content samples, which were caused due to intense coagulation.Last but not least, influences of viscosity ratio between PAN and PSA on morphology, mechanical and flame retardant properties were studied. PSA was found to be dispersed homogeneously in different PAN/PSA viscosity-ratio samples. Mechanical tests showed that under same spinning conditions, samples with similar viscosities between two blend phases resulted in a better stretchability. When the viscosity ratio of PAN/PSA increased to 2.59, IOL of blend fiber reached to 27.1% with 70wt% PSA content, thus fulfilling the requirement as a flame-retardant fiber.
Keywords/Search Tags:PAN/PSA blend fiber, dry-jet wet spinning, ionic liquid, flame-retardant fiber
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