Luffa fibers as promising reinforcement for polymer composites: Mechanical characterization of NaOH treated and untreated dumbbell test-pieces with Weibull statistics

Abstract

Different materials require specific test-piece dimensions and designations for their mechanical characterization, present either in ASTM, ISO, or DIN norms. Natural polymers or bio-fibers are materials that have lignocellulosic fibrils that can be mechanically characterized as single fibers, which tend to be bundles of thinner hollow fibrils. In this work, a new approach has been applied to the unique natural fiber Luffa cylindrica, also called loofah or scourer, as loofah dumbbell test-pieces (LDTs) similar in length to the Type IV ASTM D-638 samples for unreinforced or reinforced plastics. 60 LDTs of 120 mm and 40 mm in length and width respectively were cut by hand, with and without alkali treatment (aqueous 2%NaOH), in transversal and longitudinal directions, to be characterized using testing speeds of 1 mm/min and 50 mm/min, SEM, XRD, statistics, and Weibull analysis. The resultant force vs. elongation/stress vs. strain graphs revealed a high variability of LDTs, and mercerization was found to increase their mechanical resistance. SEM images confirmed a microtubular cellular structure, XRD exposed an increment in crystallinity after alkali treatment, and Weibull indicated the probability of failure in 10 samples per configuration.

Impact of distinct alkaline treatment on natural plant fibre reinforced polymer composites

“…From the above analysis, it is observed that higher the percentage of NaOH and KOH treated luffa fibres in the composite, the better is its tensile strength and tensile modulus, as regards to Ca(OH) 2 alkaline treatment. This result is in agreement with Carmona and Colorado L 34 who found that the tensile strength of the 2% NaOH treated luffa fibres increased to 1.5 MPa as compared to that of untreated ones. Similarly, the Ca(OH) 2 saline treatment is considered to be more suitable for increasing the tensile strength of sisal fibres.…”

“…It shows that there is significant increase in mechanical properties of the composites prepared in the current study as compared to the referred literatures. Ca(OH) 2 treated sisal fibre showed higher tensile and flexural strengths as shown in Kalusuraman et al 39 However, KOH treatment resulted in better impact strength, 34 which matches with the present experimental analysis.…”

Morphological, chemical, thermal and mechanical analysis of doum fibers as potential reinforcement of polymer composites

“…Remarkably, the cross-section shape of DPLSF closely resembles that of Sponge Gourd fibers. 26,27 Treatment of the DPLSF with sodium bicarbonate NaHCO 3…”

The real reasons for choosing bushing fiber (Luffa cylindrica): A bibliographic review

“…The use of plant fibers in composite materials is expanding every year due to the growing concern for the environment [11]. This is mainly due to the fact that these fibers have biodegradable characteristics, are less aggressive to the environment, have a great variety and availability in biodiversity, compared to the reinforcement materials currently used, they have a lower cost and are harmless to the health [23]. Therefore, natural fiber becomes an excellent alternative for use as reinforcement in composite materials [1].…”

“…Luffa sponge is a lightweight natural material that has the potential to be used as a sustainable alternative material for various engineering practice applications [10]. In addition, loofah (Luffa cylindrica) is an economic reinforcement material, as they are among the largest and most diverse families of plants, being cultivated all over the world, for supporting a variety of environmental conditions [23].…”