Menta Venkata Gireesh K, Tahir Irfan, Abutunis Abdulaziz
Department of Mechanical & Industrial Engineering, University of Minnesota Duluth, Duluth, MN 55812, USA.
Materials (Basel). 2022 Jun 23;15(13):4437. doi: 10.3390/ma15134437.
Depletion of fossil fuels and the detrimental environmental impacts of synthetic plastics have prompted a global interest in bio-based polymers. Lignin is an abundant, unused, and low-value byproduct of pulping and biochemical operations that has the potential to decrease the need for plastics derived from petroleum. Melt blending is one of the easiest strategies for expanding the commercial applications of lignin. Concerns remain, however, regarding the negative effects of lignin on the final composite material's performance, and the increase in manufacturing costs. This study investigates the effects of blending lignin extracted from tobacco using a novel one-step processing technique on injection molding parameters, and the mechanical, physical, and thermal properties of high-density polyethylene (HDPE). By extruding HDPE pellets and lignin powder, varying blend concentrations (0, 5, 10, 15, and 30% wt.) were produced. Scanning electron microscopy (SEM) and optical microscopy were used to investigate the compatibility of the blend morphology. Results indicated that interfacial interactions were achieved as particles of tobacco lignin were well dispersed and uniformly distributed throughout HDPE. Intermolecular interactions between HDPE and lignin were also discovered through Fourier-transform infrared (FTIR) spectral analyses. The tensile test results showed that increase in lignin content up to 15% wt. had little effect on tensile strength, but at 30% wt., a 19% reduction was observed. With the addition of 5, 10, 15, and 30% wt. of lignin, the tensile modulus increased by 4%, 29%, 25%, and 8%, respectively. TGA results demonstrated that at 15% and 30% wt., tobacco lignin acted as a thermal stabilizer. The processability study revealed that tobacco lignin could be processed easily using injection molding without requiring significant changes to the process parameters. Overall, tobacco lignin showed great promise as a biodegradable HDPE filler.
化石燃料的枯竭以及合成塑料对环境的有害影响引发了全球对生物基聚合物的关注。木质素是制浆和生化操作中一种丰富、未被利用且价值较低的副产品，它有可能减少对石油衍生塑料的需求。熔融共混是扩大木质素商业应用的最简单策略之一。然而，人们仍然担心木质素对最终复合材料性能的负面影响以及制造成本的增加。本研究调查了使用新型一步加工技术从烟草中提取的木质素对注塑成型参数以及高密度聚乙烯（HDPE）的机械、物理和热性能的影响。通过挤出HDPE颗粒和木质素粉末，制备了不同混合浓度（0、5、10、15和30%重量）的样品。使用扫描电子显微镜（SEM）和光学显微镜研究了共混物形态的相容性。结果表明，由于烟草木质素颗粒在HDPE中分散良好且均匀分布，实现了界面相互作用。通过傅里叶变换红外（FTIR）光谱分析还发现了HDPE和木质素之间的分子间相互作用。拉伸试验结果表明，木质素含量增加至15%重量时，对拉伸强度影响不大，但在30%重量时，拉伸强度下降了19%。添加5、10、15和30%重量的木质素后，拉伸模量分别增加了4%、29%、25%和8%。热重分析（TGA）结果表明，在15%和30%重量时，烟草木质素起到了热稳定剂的作用。加工性能研究表明，使用注塑成型可以轻松加工烟草木质素，而无需对工艺参数进行重大更改。总体而言，烟草木质素作为一种可生物降解的HDPE填料具有很大的潜力。
