The Effect of Bamboo Charcoal on Water Absorption, Contact Angle, and the Physical-Mechanical Properties of Bamboo/Low-Density Polyethylene Composites

Abstract

The use of bamboo charcoal (BC) was investigated as a filler in bambooplastic composites (BPCs) to achieve improved water resistance, physical-mechanical properties, and reduced hydrophilicity. The influence of the BC content and size on the water absorption, contact angle, density, and mechanical properties of bamboo flour/low-density polyethylene (LDPE) composites was tested. Scanning electron microscopy was used to analyse fractured and flat composite surfaces. The results indicated that the BC increased water resistance, achieving optimal results at 8% content. The BC particles that ranged in size from 60 to 100 mesh were more water-resistant than other sized BC. The water contact angle increased with an increase in the BC content or a decrease in the particle size. These results indicated that BC reduced the composite hydrophilicity and that the smaller BC particles improved this effect. The BC strongly connected with the LDPE composites, and the BC contents below 12% improved the flexural properties and increased the density of the BPCs. Also, the impact strength of the BPCs decreased dramatically with a decrease in the BC particle size. These results demonstrated that the integration of BC with BPCs resulted in strengthened water resistance and physical-mechanical properties and reduced hydrophilicity. Bamboo and Rattan and Technology of State Forestry Administration, Beijing, China, 100102; b: Sichuan Agricultural University, Key Laboratory of Wood Industry and Furniture Engineering, Chengdu, China, 611130; * Corresponding author: qindc@icbr.ac.cn Keywords INTRODUCTIONBamboo is an important natural resource that grows faster than trees and is stronger than wood (Jiang 2007). Bamboo-plastic composites (BPCs) are manufactured via hot pressing and extrusion or injection moulding using thermoplastics and bamboo instead of wood (Yeh et al. 2009;Wu et al. 2013). BPCs are widely used in decorations, outdoors, and as non-structural components of buildings (Xian et al. 2015) because they are biodegradable, renewable, and environmentally friendly materials (Zhou et al. 2015a). However, the interface between the polar, hydrophilic bamboo fibres and the non-polar, hydrophobic low-density polyethylene (LDPE) is weak, which leads to the formation of many gaps and pores between the two materials. This incompatibility results in poor mechanical properties and renders the composites vulnerable to water penetration and fungal attack (Hosseinihashemi et al. 2011;Mbarek et al. 2013). Bamboo fibre processing (Li et al. 2013) and coupling agent addition (Tran et al. 2013) are widely used PEER-REVIEWED ARTICLE bioresources.com Chen et al. (2016). "Bamboo/PE composites," BioResources 11(4), 9986-10001. 9987techniques for improving the compatibility of plant fibres and polymers. Another method of eliminating gaps is filler addition, which is a simple and low-cost way to effectively improve the composite morphology and mechanical properties. Nanofillers (Deka and Maji 2012), glass fibres (Zolfaghari et al. 2013), and carb...

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