Structural, chemical, and multi-scale mechanical characterization of waste windmill palm fiber (Trachycarpus fortunei)

Jing Li,Xuexia Zhang,Yan Yu,Hankun Wang,Jiawei Zhu

doi:10.1186/s10086-020-1851-z

Abstract

This study investigated the structural, chemical, and multi-scale mechanical properties of windmill palm (Trachycarpus fortunei) leaf sheath fiber, which were frequently wasted. Significant variation was observed in fiber diameter and cross-sectional morphology among different layers in a single leaf sheath, whereas the chemical composition, relative crystallinity index, and the microfibrillar angle (MFA) of palm fibers were almost the same among different layers. Windmill palm fibers had low cellulose contents (34.70–35.5%), low relative crystallinity index (45.7–49.2%), and high MFA (38.8°–29.4°), resulting in low strength and modulus, but high failure strain under tensile load. The tensile fracture surface of windmill palm fibers was assessed through SEM studies and its ductile fracture was confirmed, which can potentially enhance the toughness of composites when used as reinforcement material. Nanoindentation was carried out among different leaf sheath layers, and the results showed the modulus and hardness values of windmill palm fibers are in the same range as other plant fibers. The experimental results may help guide selection of suitable reinforcing fibers for use in composites in different applications.

Highlights

Over the last two decades, there has been a growing industrial interest in the development of lignocellulosic natural fibers as replacements for glass or other traditional reinforcement materials used in composites [1]
Fiber morphology A windmill palm trunk is covered with a large amount of leaf sheath (Fig. 1a), and each leaf sheath can be separated into three layers of fibers due to the orderly arrangements (Fig. 1c)
The surface was covered by arrays of protrusions (Fig. 3c), identified as silica bodies embedding circular craters under higher magnification (Fig. 3d) which had been confirmed through energy dispersive X-rays spectrometry (EDS) [19]

Summary

Introduction

Over the last two decades, there has been a growing industrial interest in the development of lignocellulosic natural fibers as replacements for glass or other traditional reinforcement materials used in composites [1]. The palm leaf sheath fiber is considered an abundant agricultural byproduct due to the necessary regular pruning process of the palm tree by removing loose mats to keep the tree attractive and safe. Due to their high durability and strength characteristics, palm fibers are used to make a variety of byproducts such as mattresses, sofas, marine ropes, sacks, and traditional raincoats [7]. These applications only utilize a small percentage of the total material produced, and the majority of the material is discarded directly as waste, causing serious environmental problems [8].

Methods

Results

Conclusion