Polymers 2023 , 15 , 1393
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composites for packaging applications. The findings indicated that bamboo fabric/PLA composites enhanced PLA impact strength by 117%, with comparatively lower impact strength observed for PP/bamboo fibre composites. Thermal stability in terms of the heat deflection temperature (HDT) of PP and PLA matrices was increased by the addition of bamboo fabric. The high heat resistance property of composites is suitable for packaging applications. Nabels-Sneiders et al. [138] studied lamination technology of cast hemp paper with bio-based plastics using a compression moulding process to replace conventional plas- tics and solve the existing waste disposal problems. They compared polyhydroxyalkanoate (PHA), polylactic acid (PLA), polybutylene succinate (PBS) and polybutylene succinate adipate (PBSA) laminates prepared at three different compression pressures. The desired pressure on porous cast paper, impregnation and excellent layer adhesion was proposed in their study. Ji et al. [139] prepared chitosan-based composite films reinforced by ramie fibre and lignin, as shown in Figure 5, for food packaging applications. The addition of 20% ramie fibre and 20% lignin improved the mechanical properties and water resistance by up to 29.6% and 41%, respectively. Food packaging studies showed extended shelf life in meat products such as chicken breasts compared with fruits such as cherry tomatoes.
Figure 5. Preparation of chitosan/ramie fibre/lignin composite films. Reprinted with permission from [139]. Copyright 2022 Elsevier Ltd. Tawakkal et al. [140] used a thymol extract with kenaf fibres to study the migration of thymol extract from PLA/kenaf composites. Melt-blending was used to prepare the films in an internal mixer (155 ◦ C for 8 min and 50 rpm) followed by heat pressing. The materials were melted by preheating (150 ◦ C for 3 min) without applying pressure and then pressed at the same temperature for 2 min with a force of 20 kN before quench cooling to 30 ◦ Cunder pressure. Tawakkal et al. [141] also studied the antimicrobial activity of PLA/kenaf/thymol against Escherichia coli bacteria and naturally occurring fungi. Films with higher thymol concentrations and higher kenaf loading exhibited excellent antibacterial properties against fungal growth due to the release of thymol into the headspace surrounding the samples; however, the shelf life after storage for 3 months at ambient temperature showed only a slight decrease in antimicrobial properties.
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