Novel phosphorus/nitrogen-rich oligomer with numerous reactive groups for durable flame-retardant cotton fabric

A phosphorus/nitrogen-rich oligomer with numerous reactive groups (PEI-P) was synthesized and used as highly efficient durable flame retardant for cotton fabric. The O=P-ONH4 and O=P-OH groups in PEI-P reacted with O-H group in cellulose during finishing process. PEI-P triggered the decomposition of cotton fabric in advance, while markedly increased the char yield at high temperature. Treated fabrics showed superior flame resistance and durability. With the add-on of 19.3%, treated fabric achieved an LOI value of 38.7%. It self-extinguished even after 50 laundering cycles during vertical burning test. The PHRR and THR decreased by 86.10% and 65.11% in contrast to control fabric, respectively. PEI-P exerted gaseous and condensed flame-retardant effects by restraining the release of flammable volatiles, producing nonflammable gases and catalyzing the formation of stable phosphorus/nitrogen-rich char layers. Compared to control fabric, treated fabrics obtained well-maintained crystal structure and physical properties.

合成了一种具有大量反应基团的富磷/氮低聚物（PEI - P），并将其用作棉织物的高效耐用阻燃剂。在整理过程中，PEI - P中的O = P - ONH₄和O = P - OH基团与纤维素中的O - H基团发生反应。PEI - P促使棉织物提前分解，同时显著提高了高温下的炭产率。经处理的织物表现出优异的阻燃性和耐久性。当添加量为19.3%时，处理后的织物极限氧指数（LOI）值达到38.7%。在垂直燃烧试验中，即使经过50次洗涤循环后仍能自熄。与对照织物相比，其热释放速率峰值（PHRR）和总热释放量（THR）分别降低了86.10%和65.11%。PEI - P通过抑制可燃挥发物的释放、产生不可燃气体以及催化形成稳定的富磷/氮炭层，发挥了气相和凝聚相阻燃作用。与对照织物相比，经处理的织物保持了良好的晶体结构和物理性能。