Micro-fibrillated cellulose (MFC) derived from natural fibre is continuously gaining interest to produce an environmentally-friendly material, due to economic and ecological reasons. In consequence, sorghum is one of the most-cultivated crops that usually remain the waste as by product of bioethanol production. Indeed, it will be a promising area to utilize sorghum waste to produce MFC for enhancing polymer performance, especially in terms of crystallinity. The objective of this study is to investigate the effect of a sequence of chemical modification was applied to sorghum fibres, i.e. alkalization using 4% sodium hydroxide followed by bleaching using 1.7% sodium chlorite plus acetic acid as a buffer. The treatment was purposed to unbundle the lignocellulose networks into microfibrils cellulose with less amorphous part and lower hydrophilic properties. Evaluation of the chemical treatments effect on internal microstructure, crystallinity index and chemical composition of sorghum fibre was measured via Field-Emission Scanning Electron microscope (FE-SEM), X-ray Diffraction (XRD) and Fourier Transformation Infra-Red (FTIR) Spectroscopy. The experiments show that treatments led to a removal of binding materials, such as amorphous parts hemicellulose and lignin, from the sorghum fibres, resulting MFC of sorghum fibres and enhanced crystallinity index from 41.12 % to 75.73%.

Increasing global concern to environmental issues and sustainability related to preservation of non-renewable natural resources has encouraged research to develop new environmental friendly materials and products based on renewable natural resources. Sorghum fiber has potential to be a composite reinforcement because it has a good mechanical properties, environmental friendly and inexpensive. The preparation process of sorghum fiber is needed to improve its compatibility with polypropylene (PP). Thermal alkalization is the method used in conducting fiber preparation. In this study, alkalization-thermal treatment with 0%, 5% and 10% NaOH and pressurized steam for 1 and 3 minutes was carried out to change the hydrophobicity of sorghum fiber. The most optimum result was obtained at 5% NaOH concentration with 3 minutes pressure-soaking, showing cleaner and fibrillated morphology based on FESEM testing. It was less lignin and hemicellulose content as indicated by FTIR testing result, better hydrophobicity as indicated through Sessil Drop testing result that showed contact angle of 120.9◦, as well as significant increase in crystallinity index of 6.3% as indicated through X-Ray Diffraction (XRD) test result. The increase in the hydrophobicity of the modified sorghum fiber indicated the increase of the natural fiber compatibility with polymer matrix.

Plastic waste that has not been appropriately managed has caused concern for various stakeholders and has a negative impact on the environment. A way to minimize this issue is by promoting a circular economy through recycling. Despite this, many plastic wastes cannot be economically recycled; one of them is multilayer plastics due to the difficulty in sorting out the various types of materials contained in the layers. As an alternative, it may be possible to utilize multilayer plastic as a bitumen mixture; this method may avoid the separation process entirely. Bitumen is a component of asphalt, which is crucial to the construction of infrastructure. Plastics can potentially enhance the properties of modified bitumen, and they would assist in enhancing the quality of the asphalt. The aim of this study is to examine the impact of multilayer waste plastics on bitumen fabricated by the hot-mixing process. To enhance the compatibility between hydrophobic plastic and hydrophilic bitumen, lignin was used as a compatibilizer. The properties of bitumen with 3, 4, and 5 wt.% multilayer plastic and mixing times of 15, 30, and 45 minutes were evaluated. Accordingly, surface, chemical, thermal properties, and morphology were evaluated using sessile drop tests, Fourier Transform Infrared, thermogravimetry analysis, and scanning electron microscopy.