International Journal of Marine Engineering Innovation and Research
Vol. 11 No. 3 (2026)

Alkali Treatment and Concentration Effects on Epoxy/Agel Fiber Composite Mechanical Properties for Marine Engineering Use

Risa Nurin Baiti (Department of Mechanical Engineering Department, Politeknik Negeri Bali, Badung, 80361, Indonesia.)
I Wayan Padma Yogi Asana (Department of Mechanical Engineering Department, Politeknik Negeri Bali, Badung, 80361, Indonesia.)
Widya Emilia Primaningtyas (Department of Marine Engineering, Politeknik Perkapalan Negeri Surabaya, Surabaya, 60111, Indonesia.)
Imah Luluk Kusminah (Department of Marine Engineering, Politeknik Perkapalan Negeri Surabaya, Surabaya, 60111, Indonesia.)
Slamet Raharjo (Department of Mechanical Engineering, Politeknik Negeri Bandung, Bandung, 40559, Indonesia.)
I Komang Adi Wiranata (Department of Mechanical Engineering Department, Politeknik Negeri Bali, Badung, 80361, Indonesia.)
Komang Widhi Widantha (Department of Mechanical Engineering Department, Politeknik Negeri Bali, Badung, 80361, Indonesia.)



Article Info

Publish Date
28 Sep 2026

Abstract

The development of polymeric composite materials in shipbuilding has increased tremendously. To improve the sustainability of ship hulls, natural fibers have gained increasing attention as an alternative reinforcement material in polymer composites due to their renewability, low cost, and favorable specific mechanical properties. One of the natural resources that can be used as fiber reinforcement is agel leaf fibers (ALF). ALF is harvested from Corypha gebanga plant that is available throughout Indonesia. However, the inherent hydrophilicity and presence of non-cellulosic constituents on natural fiber surfaces often result in poor interfacial bonding with hydrophobic polymer matrices, limiting composite performance. This study investigated the effect of NaOH concentration and alkali treatment duration on the tensile properties of agel fiber-reinforced epoxy composites. Agel fibers were treated with NaOH solutions at concentrations of 1%, 2%, 3%, 4%, and 5%, with immersion durations of 1, 2, 3, and 4 hours, then rinsed with distilled water until reaching a neutral pH (7.5–8.5). The treated fibers were used as reinforcement in epoxy matrix composites fabricated using a self-made resin transfer equipment. Tensile testing was conducted at a loading speed of 5 mm/min to evaluate tensile strength and elongation at break for each treatment combination. Results showed that both NaOH concentration and treatment duration influenced mechanical performance in different manner. The mechanical properties of composites improved with longer duration. However, the effect of alkali concentration is more complex. The strength and stiffness behaves inversely with ductility. So the optimum parameter of ALF’s alkalization should be decided carefully depending on the priority of the mechanical characteristics required in the application. Based on the dataset obtained from the experiment, it is suggested that alkali treatment in 1% NaOH for 4 hours, yields a good balance of tensile strength, modulus of elasticity, and maximum elongation among all combinations.

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Journal Info

Abbrev

ijmeir

Publisher

Subject

Automotive Engineering Control & Systems Engineering Decision Sciences, Operations Research & Management Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Physics Transportation

Description

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