Alikiotis Periklis D, Mekonnen Tizazu H
Department of Chemical Engineering, Institute of Polymer Research, Waterloo Institute of Nanotechnology, University of Waterloo, N2L 3G1 Waterloo, ON, Canada.
Department of Chemical Engineering, Institute of Polymer Research, Waterloo Institute of Nanotechnology, University of Waterloo, N2L 3G1 Waterloo, ON, Canada.
Int J Biol Macromol. 2025 Sep;321(Pt 4):146527. doi: 10.1016/j.ijbiomac.2025.146527. Epub 2025 Aug 5.
Lignin is the second most abundant biopolymer and has generally been discarded as waste, but its availability, renewability, and unique properties have garnered popularity for its use in material applications. Its hydrophobic nature makes it a natural contender as a filler for polyvinyl chloride (PVC), a versatile polymer that is typically modified with a variety of toxic additives that can leach during thermal decomposition, whether through recycling or combustion. In this work, the applicability of Kraft lignin as a filler to PVC is explored, utilizing different grades of Kraft lignin from various purification methods and varying the loading of filler within PVC. The grade of lignin was a major aspect of the resulting mechanical properties due to the ash content, which decreased the elongation by up to 73 % in certain cases, but increased Young's modulus overall. Increasing concentrations of lignin amplified certain properties seen, with an optimal value at a loading of 18 wt%. Here, we see the most retained heat capacity (-5.14 %) and an increase to Young's modulus (+8.76 %). This loading slightly reduced the limiting oxygen index (LOI) (-9.60 %), but improved combustion indices by 50 to 80 %, through its charring behaviour. The industrially purified lignin maintained the largest elongation (-38.7 %) with similar combustion improvements, but lowered the heat capacity more (-21.3 %) compared to the laboratory purified lignin. Kinetic analysis showed a slight increase to the activation energy of dehydrochlorination and a change to the primary mechanism, shifting from nucleating to diffusion controlled.
木质素是第二丰富的生物聚合物，通常被当作废物丢弃，但因其可用性、可再生性及独特性能，在材料应用中受到青睐。其疏水性使其成为聚氯乙烯（PVC）填料的天然选择，PVC是一种通用聚合物，通常用各种有毒添加剂改性，这些添加剂在热分解过程中（无论是通过回收还是燃烧）可能会渗出。在这项工作中，研究了硫酸盐木质素作为PVC填料的适用性，使用了来自不同纯化方法的不同等级硫酸盐木质素，并改变了PVC中填料的负载量。木质素的等级是影响最终机械性能的一个主要因素，这是由于灰分含量，在某些情况下，灰分含量使伸长率降低了73%，但总体上提高了杨氏模量。木质素浓度的增加放大了某些性能，在负载量为18 wt%时达到最佳值。在此，我们看到热容量保留最多（-5.14%），杨氏模量增加（+8.76%）。该负载量略微降低了极限氧指数（LOI）（-9.60%），但通过其炭化行为使燃烧指数提高了50%至80%。工业纯化的木质素保持了最大伸长率（-38.7%），燃烧性能也有类似改善，但与实验室纯化的木质素相比，热容量降低更多（-21.3%）。动力学分析表明，脱氯化氢的活化能略有增加，主要机理发生了变化，从成核控制转变为扩散控制。
