Sulaiman Muhammad, Iqbal Tanveer, Yasin Saima, Mahmood Hamayoun, Shakeel Ahmad
Department of Chemical, Polymer & Composite Materials Engineering, University of Engineering and Technology, Lahore (New Campus), Kala Shah Kaku-39020, Pakistan.
Department of Hydraulic Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands.
Materials (Basel). 2020 Nov 5;13(21):4977. doi: 10.3390/ma13214977.
In this work, the effects of chemical pretreatment and different fiber loadings on mechanical properties of the composites at the sub-micron scale were studied through nanoindentation. The composites were prepared by incorporating choline chloride (ChCl) pretreated rice husk waste (RHW) in low-density polyethylene (LDPE) using melt processing, followed by a thermal press technique. Nanoindentation experiments with quasi continuous stiffness mode (QCSM) were performed on the surface of produced composites with varying content of pretreated RHW (i.e., 10, 15, and 20 wt.%). Elastic modulus, hardness, and creep properties of fabricated composites were measured as a function of contact depth. The results confirmed the appreciable changes in hardness, elastic modulus, and creep rate of the composites. Compliance curves indicated that the composite having 20 wt.% of pretreated RHW loading was harder compared to that of the pure LDPE and other composite samples. The values of elastic modulus and hardness of the composite containing 20 wt.% pretreated RHW were increased by 4.1% and 24% as compared to that of the pure LDPE, respectively. The creep rate of 42.65 nm/s and change in depth of 650.42 nm were also noted for the composite with RHW loading of 20 wt.%, which showed the substantial effect of holding time at an applied peak load of 100 mN. We believe that the developed composite could be a promising biodegradable packaging material due to its good tribo-mechanical performance.
在本研究中，通过纳米压痕技术研究了化学预处理和不同纤维含量对亚微米尺度下复合材料力学性能的影响。采用熔融加工方法，将氯化胆碱（ChCl）预处理的稻壳废料（RHW）加入低密度聚乙烯（LDPE）中制备复合材料，随后采用热压技术。对含有不同含量预处理稻壳废料（即10%、15%和20%重量比）的复合材料表面进行了准连续刚度模式（QCSM）的纳米压痕实验。测量了制备的复合材料的弹性模量、硬度和蠕变性能随接触深度的变化。结果证实了复合材料的硬度、弹性模量和蠕变速率发生了显著变化。柔度曲线表明，与纯LDPE和其他复合材料样品相比，含有20%重量比预处理稻壳废料的复合材料更硬。与纯LDPE相比，含有20%重量比预处理稻壳废料的复合材料的弹性模量和硬度值分别提高了4.1%和24%。对于稻壳废料含量为20%重量比的复合材料，还记录到蠕变速率为42.65 nm/s，深度变化为650.42 nm，这表明在100 mN的施加峰值载荷下保持时间的显著影响。我们认为，由于其良好的摩擦力学性能，所开发的复合材料可能是一种有前途的可生物降解包装材料。
