Zhang Shuai, Chen He, Zhang Yin, Zhang Yi-Meng, Kan Weiyan, Pan Mingzhu
College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China.
Polymers (Basel). 2020 Feb 5;12(2):336. doi: 10.3390/polym12020336.
To derive P,N-doped cellulose fibrils, phosphoric acid and aqueous ammonia were placed in a one-pot reaction, and the phosphate groups and ammonium phosphates were successfully introduced into the cellulose surface. The obtained P,N-doped cellulose fibrils with high liberation were thereafter incorporated into a high-density polyethylene (HDPE) matrix to improve the flame retardancy of HDPE composites, and they had a significant improvement on flame retardancy of HDPE composites. In particular, 7 wt % P,N-doped cellulose fibrils considerably reduced the average and peak heat release rate (HRR) by 29.6% and 72.9%, respectively, and increased the limited oxygen index (LOI) by 30.5%. The presence of phosphate groups and ammonium phosphates within P,N-doped cellulose fibrils was found to promote the thermal degradation of HDPE composites at a lower temperature (i.e., 240 °C). The released acid catalyzed the dehydration of cellulose to form an aromatic carbonaceous structure with a higher crystalline orientation, which improves the flame retardancy of HDPE composites.
为了制备磷、氮掺杂的纤维素原纤维，将磷酸和氨水置于一锅反应中，成功地将磷酸基团和磷酸铵引入纤维素表面。随后将所获得的具有高释放率的磷、氮掺杂纤维素原纤维加入高密度聚乙烯（HDPE）基体中，以提高HDPE复合材料的阻燃性，它们对HDPE复合材料的阻燃性有显著改善。特别是，7 wt%的磷、氮掺杂纤维素原纤维分别使平均热释放速率（HRR）和峰值热释放速率大幅降低了29.6%和72.9%，并使极限氧指数（LOI）提高了30.5%。发现磷、氮掺杂纤维素原纤维中的磷酸基团和磷酸铵的存在促进了HDPE复合材料在较低温度（即240℃）下的热降解。释放出的酸催化纤维素脱水形成具有更高结晶取向的芳香碳质结构，从而提高了HDPE复合材料的阻燃性。
