Bioproducts Discovery and Development Centre, Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada.
School of Engineering, Thornbrough Building, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada.
Molecules. 2020 Mar 24;25(6):1455. doi: 10.3390/molecules25061455.
Polyamide 6,6 (PA66)-based biocomposites with low-cost carbonaceous natural fibers (i.e., soy hulls, co-product from soybean industry) were prepared through twin-screw extrusion and injection molding. The soy hull natural fiber was pyrolyzed at two different temperatures (500 °C and 900 °C denoted as BioC500 and BioC900 respectively) to obtain different types of biocarbons. The BioC500 preserved a higher number of functional groups as compared to BioC900. Higher graphitic carbon content was observed on the BioC900 than BioC500 as evident in Raman spectroscopy. Both biocarbons interact with the PA66 backbone through hydrogen bonding in different ways. BioC900 has a greater interaction with N-H stretching, while BioC500 interacts strongly with the amide I (C=O stretching) linkage. The BioC500 interrupts the crystallite growth of PA66 due to strong bond connection while the BioC900 promotes heterogeneous crystallization. Dynamic mechanical analysis shows that both biocarbons result in an increasing storage modulus and glass transition temperature with increasing content in the BioC/PA66 biocomposites over PA66. Rheological analysis shows that the incorporation of BioC900 results in decreasing melt viscosity of PA66, while the incorporation of BioC500 results in increasing the melt viscosity of PA66 due to greater filler-matrix adhesion. This study shows that pyrolyzed soy hull natural fiber can be processed effectively with a high temperature (>270 °C) engineering plastic for biocomposites fabrication with no degradation issues.
采用双螺杆挤出和注塑成型工艺，制备了以低成本碳质天然纤维（如大豆壳，大豆工业的副产品）为原料的聚酰胺 6,6（PA66）基生物复合材料。将大豆壳天然纤维分别在两个不同温度（500°C 和 900°C，分别表示为 BioC500 和 BioC900）下进行热解，得到不同类型的生物炭。与 BioC900 相比，BioC500 保留了更多的官能团。拉曼光谱表明，BioC900 上的石墨化碳含量高于 BioC500。两种生物炭都通过氢键以不同的方式与 PA66 主链相互作用。BioC900 与 N-H 伸缩振动的相互作用更强，而 BioC500 与酰胺 I（C=O 伸缩）键强烈相互作用。BioC500 通过强键连接中断 PA66 的微晶生长，而 BioC900 促进异质结晶。动态力学分析表明，随着 BioC/PA66 生物复合材料中 BioC 含量的增加，两种生物炭都导致储能模量和玻璃化转变温度增加。流变分析表明，BioC900 的加入降低了 PA66 的熔体粘度，而 BioC500 的加入由于填料与基体之间的附着力增加，导致 PA66 的熔体粘度增加。本研究表明，热解大豆壳天然纤维可以与高温（>270°C）工程塑料有效加工，用于制备生物复合材料，而不会出现降解问题。
