Polymers 2023 , 15 , 1393
4of 21
Figure 2. Commonly available natural plant fibres and their sources [32–60] Agave fiber figure Reprinted with permission from Ref. [58]. Copyright 2021 Elsevier Ltd. 2.1.1. Hemp ( Cannabis sativa ) Hemp is one of the most widely utilised natural fibres after sisal as reinforcement for composites [61]. Hemp is grown widely in the EU, China, the Philippines and Central Asia. The plants are cultivated from seed and can grow up to 5 m in height. Crops cultivated for fibre are densely sown and produce plants averaging 2–3 m in height with almost no branching. Hemp fibres have antibacterial properties [62–64] emanating from cannabinoids, alkaloids, other bioactive components or lignin [65]. Khan et al. [66] studied the antibacterial properties of hemp hurd powder against E. coli using retted, semi-retted and non-retted hemp hurd powder with different particle sizes. The fibres were kept at 160 ◦ C for 2 h to eliminate self-contaminations such as humidity and thermal history. These authors found that hemp was an ecofriendly food packaging material suitable for meat, salads and ready-made food products. Teixeira et al. [67] studied the temperature effects on mechanical strength of hemp fibres. They found that tensile strength increased by 18% once the fibres were exposed to 100 ◦ C for 24 h. However, when exposed to 200 ◦ Cfor 24h, tensile properties decreased and the fibres became fragile and brittle.
Made with FlippingBook Digital Proposal Creator