Alkali treatment of hemp fibres for the production of aligned hemp fibre mats for composite reinforcement

Abstract

The main objective of this study was to produce aligned hemp fibre mats from high strength hemp fibres using dynamic sheet forming (DSF). Alkali treatment of hemp fibre was carried out at ambient and high temperature to separate fibres. Single fibre tensile testing was used to assess the tensile properties of the fibres. It was found that the highest tensile properties were exhibited by high temperature treated fibre, whereas the tensile properties exhibited by ambient temperature treated fibre were lower than for untreated fibre. It was also found that fibre granulated after high temperature treatment, was better separated than that granulated before high temperature treatment. This well-separated fibre could successfully be formed into mats using DSF. The orientation of the formed mat was analysed using ImageJ (NIH, USA) software by which the potential of DSF to produce aligned hemp fibre mat was supported. The mechanical performance of composite reinforced by these aligned hemp fibre mats were assessed.

Improving the Alignment of Dynamic Sheet-Formed Mats by Changing Nozzle Geometry and Their Reinforcement of Polypropylene Matrix Composites

“…Alkali treated hemp fibres were used to produce fibre mats. The alkali treatment and characterisation of fibres have been detailed in a previously published work [8]. The fibres had an average length and an average diameter of 1.88 mm and 0.05 mm, respectively.…”

“…A program was written in MATLAB to obtain the FWHM. [8]. Table 2 shows the stacking arrangements of the fibre…”

“…Production of PP/MAPP sheets, composites and tensile testing (quasi-static loading) are detailed in published work [8]. Table 2 shows the stacking arrangements of the fibre mats and the PP/MAPP sheets with relative numbers of each based on the targeted weight percentages of fibre mats.…”

An Overview of Alkali Treatments of Hemp Fibres and Their Effects on the Performance of Polymer Matrix Composites

“…Among the two different alkali treatments (high temperature and ambient temperature) for hemp fibres, it has been reported that most of the high temperature treatments maintained or increased the fibre tensile strength (or reduction reported for tensile strength was lower) compared to that of untreated fibre, whereas most reported ambient temperature treatments reduced the fibre tensile strength [40]. The removal of weak components has explained the increase in tensile strength of the high temperature treated fibre, and thus, the remaining material is stronger.…”

Effect of NaOH Treatment on the Flexural Modulus of Hemp Core Reinforced Composites and on the Intrinsic Flexural Moduli of the Fibers

“…Regarding process yields, soft NaOH treatments involve lower waste generation, which is a goal of the circular economy and agrees with the principles of green chemistry [ 29 ]. The fiber’s morphology is also affected by lignin removal, since fiber individualization is promoted, achieving higher aspect ratios and contributing to the enhancement of the mechanical properties [ 30 , 31 ].…”