Evaluation of thermal, morphological and flame-retardant properties of thermoplastic polyurethane/polyphosphazene blends
Evaluation of thermal, morphological and flame-retardant properties of thermoplastic polyurethane/polyphosphazene blends
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DOI：
10.1007/s00289-017-2156-2
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发表时间：
2018-06
期刊：
影响因子：
3.2
通讯作者：
K. P. Singh;A. Mishra;Nand Kumar;D. N. Tripathi;T. C. Shami
中科院分区：
文献类型：
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作者：
K. P. Singh;A. Mishra;Nand Kumar;D. N. Tripathi;T. C. Shami
以六氯磷腈(三聚体)为原料，通过热开环聚合制备了聚二氯磷腈。用三氟乙醇钠和呋喃醇盐取代氯基，对聚二氯磷腈进行官能化处理，并用凝胶渗透色谱分析、红外光谱和核磁共振光谱对官能化聚磷腈的结构进行了表征。在无水四氢呋喃溶剂中，用溶液浇铸法进一步将PPZ与热塑性聚氨酯(TPU)共混。通过红外光谱观察了TPU/PPZ共混物的相容行为，揭示了TPU/PPZ共混物相容的原因是由于TPU与PPZ之间的分子间氢键作用。用热重分析(TGA)和差示扫描量热法(DSC)分析了浇铸膜的热性能，发现随着PPZ含量的增加，热塑性聚氨酯的降解起始温度升高。当聚磷腈的用量从5wt%增加到20wt%时，600℃下共混物的成炭率也得到了提高。用X射线衍射仪分析了PPZ异核化作用对TPU/PPZ共混物结晶度的影响。此外，用扫描电子显微镜研究了TPU/PPZ共混膜的形态变化，揭示了共混物(D)的均匀性。用极限氧指数(LOI)分析仪和UL-94(垂直燃烧试验)对共混物的阻燃性能进行了评价，共混物(D)的阻燃等级为V0，LOI值为31.4%。此外，用UTM对薄膜的力学性能进行了表征，结果表明，在共混物中加入20wt%的PPZ，共混物的拉伸强度提高了约110%，断裂伸长率降低了近13%。
A polydichlorophosphazene was prepared by thermal ring-opening polymerization of hexachlorophosphonitrile (trimer). The functionalization of polydichlorophosphazene was done via substituting the chlorine groups with sodium salt of trifluroethanol and furfuryl alcohol and then structural properties of functionalized polyphosphazene (PPZ) was confirmed by GPC, FT-IR and NMR spectroscopic analysis. The PPZ was further blended with thermoplastic polyurethane (TPU) using solution casting method in anhydrous tetrahydrofuran solvent. The miscibility behavior of TPU/PPZ blends was observed via FTIR spectroscopy which unfolded the reason of compatibility of the blends due to intermolecular Hydrogen bonding interaction between the TPU and PPZ. Further, the thermal properties of the casted films were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) which revealed the increase in onset of degradation temperature of TPU with the increase of PPZ content. Also the char yields of TPU blends at 600 °C were increased upon increasing the amount of polyphosphazene from 5 to 20 wt%. The appearance of crystallinity in the TPU/PPZ blend due to heteronucleation effect by PPZ was analyzed by X-ray diffractometer. Besides this, the morphological changes of the TPU/PPZ blended films were investigated by scanning electron microscopy which exposed the homogeneity in the blend (d). The flame-retardant properties were evaluated using limiting oxygen index (LOI) analyzer and UL-94 (vertical burning test) showing the rating of V0 with achieved LOI value of 31.4% for the blend (d). Moreover, the films were characterized in terms of mechanical properties (as per relevant ASTM standards) using UTM which demonstrated that the addition of 20 wt% PPZ in the blend enhanced the tensile strength by about 110% and decreased the elongation at break by nearly 13%.