High-Quality Natural Fibers from Cotton Stalk Bark via Limited Alkali Penetration and Simultaneous Accelerated Temperature Rise.

Zhen Dong,Aixue Dong,Teye Chu,Junxiong Zhang,Na Li,Jiangxin Ding

doi:10.3390/ma15020422

Abstract

High-quality cotton stalk fibers that are both fine and have a high breakage strength are extracted via limited alkali penetration in the glycerol solvent and simultaneous accelerated temperature rise by means of microwave-assisted heating. Alkali is widely used in the extraction of cotton stalk fibers. However, alkali molecules in the aqueous phase penetrate easily into the fiber bundles, resulting in a simultaneous degumming between the inner and outer layers of the fiber bundles. In previous reports, the fibers treated in the aqueous phase present a coarse fineness (51.0 dtex) under mild conditions or have a poor breakage strength (2.0 cN/dtex) at elevated temperatures. In this study, glycerol is chosen as a solvent to reduce the penetration of alkali. Simultaneously, the microwave-assisted heating form is adopted to increase the temperature to 170 °C within 22 s. The inhibited alkali penetration and accelerated temperature rise limited the delignification to the outer layer, resulting in fibers with both appropriate fineness (23.8 dtex) and high breakage strength (4.4 cN/dtex). Moreover, the fibers also exhibit a clean surface and large contact angle. In this paper, we detail a new strategy to extract high-quality lignocellulosic fibers that will be suitable for potential reinforcing applications.

Highlights

Cotton stalks are one of the major agricultural byproducts that are copious and inexpensive but have limited use in high-value applications
Reddy and Yang found that the cotton stalk fibers that were treated in an 8 wt % alkaline aqueous solution at 90 ◦ C had a fineness of 51 dtex [11], too coarse for high valuable applications [12]
This paper aims to study a novel strategy to extract natural fibers from the bark of cotton stalks with both appropriate fineness and high breakage strength

Summary

Introduction

Cotton stalks are one of the major agricultural byproducts that are copious and inexpensive but have limited use in high-value applications. Alkaline treatment methods are widely used in extracting natural fibers from the agricultural wastes, including thespesia populnea bark [7], grape cane [8], Juncus effusus [9], cotton stalks [10], etc. Most of these alkaline treatments are carried out in the water phase, which is beneficial to the dissolution of lignin and other gum substances. Reddy and Yang found that the cotton stalk fibers that were treated in an 8 wt % alkaline aqueous solution at 90 ◦ C had a fineness of 51 dtex [11], too coarse for high valuable applications [12]. To the best of our knowledge, no reports have been available in solving the problem of strength loss during the fiber extraction process

Objectives

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Conclusion