Treatment of hemp fibres for use in rotational moulding

Abstract

The benefit of using alkali-treated hemp fibre as the reinforcement for rotationally moulded polyethylene composites was evaluated in this research. Untreated and alkali-treated hemp fibre were characterised using different techniques such as scanning electron microscopy (SEM), thermal analysis, and Fourier transform infrared spectroscopy (FT-IR). These techniques showed that the alkali treatment removed non-cellulosic components from hemp fibres, which improved their separation and thermal resistance. Composites with alkali-treated fibre resisted the exposure to elevated temperatures for prolonged periods (characteristic of the rotational moulding process) with no apparent signs of thermal degradation, unlike when untreated fibre was used. The effect of using maleic anhydride grafted polyethylene (MAPE) as a coupling agent was also investigated. The addition of 3 wt% MAPE improved the properties tensile strength and Young's modulus of composites with treated hemp fibre, which was attributed to better fibre-matrix adhesion. Different fibre contents were assessed in this research to produce rotationally moulded composites; a poor fibre distribution was observed above 5 wt% fibre content, which resulted in low tensile strength and Young's modulus.

Use of Ricinus communis shredded material as filler in rotational molded parts to improve the bio-disintegration behavior

“…The composites with treated Ricinus also led to thicker walls due to the formation of clusters and voids appearing. In any case, the inner surface of the parts shows an acceptable quality, with no excessive number of voids or fiber balls inside the mold (not integrated into the part), as pointed out in other papers [33]. Darker color and intense smell are obtained for untreated material parts, which means that NaOH treatment is needed in this case to increase the thermal stability (as also observed from TGA analysis).…”

“…The literature shows that the introduction of fillers significantly affects tensile and impact strength while modules remain unchanged or even tend to increase [12,42]. For example, Oliveira et al have found that using 5% hemp fibers resulted in a reduction in tensile strength and modulus higher than 50%; the use of NaOH-treated fibers allows for reducing this drop, especially for modulus [33]. Abhilash and collaborators finally found that 10% of bamboo fibers can be introduced into the PE matrix without significant decreases in mechanical properties (apart from impact strength, which is also significantly decreased) [19].…”

Valorization of Invasive Plants from Macaronesia as Filler Materials in the Production of Natural Fiber Composites by Rotational Molding

“…Sari and collaborators [ 40 ] also proposed the use of the plasma activation of PE to increase its adhesion with coir fibers, demonstrating improvements in impact strength—although only 5% fiber composites were produced. Finally, Oliveira et al [ 41 ] were only able to introduce up to 5% of hemp fibers into a PE matrix without worsening the mechanical properties, even for NaOH- and MAPE-treated fibers.…”

Environmental Hazards of Giant Reed (Arundo donax L.) in the Macaronesia Region and Its Characterisation as a Potential Source for the Production of Natural Fibre Composites

“…The infrared analysis confirms the chemical composition data obtained by hydrolysis, which show a lower lignin content for the leaves and roots samples, and a higher proportion of cellulose for the fibres. As shown in Figure 7 , at 1730 cm −1 the peak corresponding to the C=O vibration of ketone or carbonyl groups (mainly associated with the presence of hemicellulose [ 32 ], although it may also be due to pectins and waxes) can be observed. This peak occurs for all parts of the plant, although for leaf and root samples, this peak is of very low intensity.…”