Ningbo Key Laboratory of Polymer Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China; School of Material Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, PR China.
Laboratory of Polymer Materials and Engineering, NingboTech University, Ningbo 315100, China.
Int J Biol Macromol. 2022 Oct 31;219:558-570. doi: 10.1016/j.ijbiomac.2022.07.172. Epub 2022 Jul 27.
Two kinds of phosphoramide derivatives containing one (POFA) or two (BPOFA) phosphoramide bonds were synthesized using diphenylphosphinic chloride, phenylphosphonic dichloride and furfurylamine, respectively. The flame retardancy, thermal degradation and crystallization behaviors of polylactic acid (PLA)/POFA and PLA/BPOFA blends were investigated using the limiting oxygen index (LOI), UL-94 vertical burning tests, cone calorimeter tests, thermogravimetric analysis and differential scanning calorimetry. A small amount of 1.0 wt% BPOFA increases the LOI of PLA from 20.4 vol% to 28.0 vol% and achieves the UL-94 V0 rating, while 7.0 wt% POFA is needed to achieve the UL-94 V0 rating indicating that the PLA/BPOFA has better flame retardancy than that of PLA/POFA. Both POFA and BPOFA decrease the amount of flammable gaseous compounds and play positive roles in transesterification of PLA. More importantly, BPOFA is easier to catalyze the degradation of PLA and improve UL-94 rating by melting-away mode. Moreover, the BPOFA accelerates the crystallization rate and thus improves the crystallinity of PLA, while POFA does not show a positive effect on crystallization behaviors of PLA.
两种含一个（POFA）或两个（BPOFA）膦酰胺键的膦酰胺衍生物分别用二苯基磷酰氯、二苯基膦酸二氯和糠胺合成。采用氧指数（LOI）、UL-94 垂直燃烧试验、锥形量热仪试验、热重分析和差示扫描量热法研究了聚乳酸（PLA）/POFA 和 PLA/BPOFA 共混物的阻燃性、热降解和结晶行为。少量的 1.0wt% BPOFA 将 PLA 的 LOI 从 20.4vol%提高到 28.0vol%，并达到 UL-94 V0 等级，而需要 7.0wt% POFA 才能达到 UL-94 V0 等级，表明 PLA/BPOFA 的阻燃性优于 PLA/POFA。POFA 和 BPOFA 均减少了可燃气态化合物的量，并在 PLA 的酯交换反应中发挥了积极作用。更重要的是，BPOFA 更容易通过熔融消除模式催化 PLA 的降解并提高 UL-94 等级。此外，BPOFA 加速了 PLA 的结晶速率，从而提高了 PLA 的结晶度，而 POFA 对 PLA 的结晶行为没有积极影响。
