Stabilization effect of kraft lignin into PBAT:Thermal analyses approach

ABSTRACT Sterically hindered phenols are an important class of synthetic antioxidants for polymers, commonly incorporated to inhibit polyolefins or polyesters oxidation. However, synthetic antioxidants use is under restricted regulation due to their potential health risk and environmental impacts. Thus, great interest has been attracted to the phenol-based natural antioxidant such as lignin. This work aimed to evaluate the thermostability of kraft lignin (KL) as a natural antioxidant when incorporated into poly(butylene adipate-coterephthalate) (PBAT) matrix. PBAT-KL films (0%, 1%, 3%, 5% and 10%, by mass) were prepared by twin-screw extrusion followed by thermo-compression. These materials were examined in detail for their effect on the thermal stability using the oxidative induction time (OIT), oxidative induction temperature (OITemp) and thermogravimetric analysis (TG). According to the results, lignin-containing compositions have improved thermal resistance in oxidative environment, compared to neat PBAT. However, 10 wt.% lignin composition presented the lowest thermostability among lignin-containing compositions. The results showed that kraft lignin promotes the thermal stabilization of PBAT films at the optimal concentration of 1% by mass.

摘要 位阻酚是一类重要的聚合物合成抗氧化剂，通常被添加以抑制聚烯烃或聚酯的氧化反应。然而，合成抗氧化剂因存在潜在健康风险与环境影响，其使用正受到日益严格的监管。因此，木质素这类酚类天然抗氧化剂受到了广泛关注。本研究旨在评估牛皮纸木质素（kraft lignin, KL）作为天然抗氧化剂，添加至聚己二酸-对苯二甲酸丁二醇酯（poly(butylene adipate-coterephthalate), PBAT）基体中的热稳定性能。通过双螺杆挤出结合热压工艺，制备了质量分数分别为0%、1%、3%、5%和10%的PBAT-KL复合薄膜。采用氧化诱导时间（oxidative induction time, OIT）、氧化诱导温度（oxidative induction temperature, OITemp）以及热重分析（thermogravimetric analysis, TG），对这些材料的热稳定性能影响进行了详细表征。结果表明，与纯PBAT相比，添加木质素的复合体系在氧化环境下的热阻性能得到提升；但在所有含木质素的复合体系中，10%质量分数的木质素添加组热稳定性最差。研究结果证实，牛皮纸木质素在1%质量分数的最优添加量下，可有效提升PBAT薄膜的热稳定性能。