Chemical Treatments for Modification of the Surface Morphology of Coir Fiber: A Review

ABSTRACT

Coir fiber is obtained from the hard outer shell of the coconut. They are cost-effective, easily available, and easily processed. Composites made from natural fibers also have much-varied applicability. Coir fiber has been used to reinforce many matrices like polyethylene, polypropylene, epoxy, etc. But one of the common problems observed is the hydrophilicity and weak adhesion of the fibers with matrix material, which leads to reduced strength and durability of the finished product. This paper is an attempt to study the Coir fibers and various types of techniques applied to improve the surface interaction of these fibers. The treatment techniques include mercerization, silane treatment, effect of coupling agents and their effect on the strength of composites prepared is reported. These techniques help improve the fiber-matrix adhesion, makes the fiber surface clean and rough, reduce the water absorption and increase the wettability of Coir fibers. fiber treatment leads to a drastic increase in the strength and morphology of final product as is evident from the mechanical and morphological results. Scanning Electron Microscopy (SEM) has shown that the modification of fibers leads to better fiber–matrix interaction due to the subsequent changes in the surface morphology.

摘要

椰子纤维是从椰子坚硬的外壳中提取的. 它是一种用途广泛的纤维, 属于天然纤维. 天然纤维比合成纤维有许多优点. 它们具有成本效益、易于获取和处理. 由天然纤维制成的复合材料也有多种适用性. 椰壳纤维已被用于增强许多基体, 如聚乙烯、聚丙烯、环氧树脂等. 但观察到的一个常见问题是纤维与matrix材料的亲水性和弱粘附性, 这导致成品的强度和耐久性降低. 本论文旨在研究椰壳纤维以及改善椰壳纤维表面相互作用的各种技术. 报道了丝光处理、硅烷处理、偶联剂的作用及其对复合材料强度的影响. 这些技术有助于提高纤维基体的附着力, 使纤维表面清洁粗糙, 降低吸水率, 增加椰壳纤维的润湿性. 从力学和形态学结果可以明显看出, 纤维处理导致最终产品的强度和形态急剧增加. 扫描电子显微镜(SEM)显示, 由于随后表面形貌的变化, 纤维的改性导致更好的纤维-基体相互作用.

KEYWORDS:

• Composites
• Fibers
• surfaces
• treatment
• strength

Highlights

• One of the natural lignocellulosic fiber i.e. Coir fiber is studied for its surface treatment in order to render it hydrophobic.

• Past 20 years chemical treatment namely mercerization (with varied soaking time and varied alkali percentage), acetylation, coupling agent, and combined effect of all was observed.

• 5% alkali concentration is found optimum to achieve maximum strength and immersion time of 72 hrs.

• Coupling agent like silane treatment is also equally effective in achieving good strength.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.