Khan Naveed Ahmed, Niazi Muhammad Bilal Khan, Sher Farooq, Jahan Zaib, Noor Tayyaba, Azhar Ofaira, Rashid Tazien, Iqbal Naseem
Department of Chemical Engineering, School of Chemical and Materials Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan.
Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK.
Polymers (Basel). 2021 Jul 14;13(14):2307. doi: 10.3390/polym13142307.
Bio-nanocomposites-based packaging materials have gained significance due to their prospective application in rising areas of packaged food. This research aims to fabricate biodegradable packaging films based upon polyvinyl alcohol (PVA) and starch integrated with metal-organic frameworks (MOFs) or organic additives. MOFs offer unique features in terms of surface area, mechanical strength, and chemical stability, which make them favourable for supporting materials used in fabricating polymer-based packaging materials. zeolitic imidazolate frameworks (ZIFs) are one of the potential candidates for this application due to their highly conductive network with a large surface area and high porosity. Present research illustrates a model system based on ZIF-67 (CHNCo) bearing 2-10 wt.% loading in a matrix of PVA/starch blend with or without pyrolysis to probe the function of intermolecular interaction in molecular packing, tensile properties, and glass transition process. ZIF-67 nanoparticles were doped in a PVA/starch mixture, and films were fabricated using the solution casting method. It was discovered through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) that addition of ZIF-67 and pyrolyzed ZIF-67 changed and enhanced the thermal stability of the membrane. Moreover, 2-10 wt.% loading of ZIF-67 effected the thermal stability, owing to an interlayer aggregation of ZIF-67. The membranes containing pyrolyzed ZIF-67 showed mechanical strength in the order of 25 MPa in a moderate loading of pyrolyzed ZIF-67 (i.e., at 4 wt.%). The crystallinity enhanced by an increment in ZIF-67 loading. On the other hand, pyrolyzed ZIF-67 carbon became amorphous because of the inert environment and elevated temperature. The surface area also increased after the pyrolysis, which helped to increase the strength of the composite films.
基于生物纳米复合材料的包装材料因其在包装食品新兴领域的潜在应用而受到关注。本研究旨在制备基于聚乙烯醇（PVA）和淀粉，并与金属有机框架（MOF）或有机添加剂相结合的可生物降解包装薄膜。MOF在表面积、机械强度和化学稳定性方面具有独特特性，这使其有利于作为制备聚合物基包装材料的支撑材料。沸石咪唑酯骨架（ZIF）因其具有高导电性网络、大表面积和高孔隙率，是该应用的潜在候选材料之一。目前的研究展示了一个基于ZIF-67（CHNCo）的模型系统，其在PVA/淀粉共混物基质中的负载量为2-10 wt.%，有无热解情况，以探究分子间相互作用在分子堆积、拉伸性能和玻璃化转变过程中的作用。将ZIF-67纳米颗粒掺杂到PVA/淀粉混合物中，并采用溶液浇铸法制备薄膜。通过扫描电子显微镜（SEM）、X射线衍射（XRD）、热重分析（TGA）和傅里叶变换红外光谱（FTIR）发现，添加ZIF-67和热解后的ZIF-67改变并提高了薄膜的热稳定性。此外，由于ZIF-67的层间聚集，2-10 wt.%的ZIF-67负载量影响了热稳定性。含有热解后ZIF-67的薄膜在热解后ZIF-67的中等负载量（即4 wt.%）下显示出约25 MPa的机械强度。随着ZIF-67负载量的增加，结晶度提高。另一方面，由于惰性环境和温度升高，热解后的ZIF-67碳变成了无定形。热解后表面积也增加了，这有助于提高复合薄膜的强度。
