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. 2025 Oct 15;15(1):36081.
doi: 10.1038/s41598-025-19991-8.

Influence of alkali treatment in enhancing crystallinity and breaking force of pineapple leaf fiber

Dharanendra Y T  1 , Jamaluddin Hindi  1 , Gurumurthy B M  1 , Muralishwara K  2
Affiliations

Influence of alkali treatment in enhancing crystallinity and breaking force of pineapple leaf fiber

Dharanendra Y T et al. Sci Rep. .

Abstract

The study investigates the effect of alkali treatment on pineapple leaf fiber (PALF) woven mats. The woven mat was chemically treated with varied concentrations (3, 6, and 9% w/v) of sodium hydroxide (NaOH) solutions for different exposure times (30, 60, and 90 min), making a total of 9 experiments. The structural, morphological, and chemical properties of untreated and alkali-treated specimens were investigated by using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) respectively. The mechanical property was assessed through the breaking force analysis. The XRD result indicated that the fiber mat treated with NaOH of 6% w/v concentration exposed to 30 min yields a crystallinity index (CI) of 63.95% and a crystallite size (CS) of 7.05 nm. The FTIR analysis helped to identify chemically active groups involved in PALF and the characteristic absorption peaks associated with partial and complete removal of wax and other impurities. SEM results quantitatively indicated the elimination of amorphous components from the surfaces. The specimen with the highest CI of 63.95% exhibited the maximum breaking force of 356.92 N. The results indicate that the increase in CI and CS not only improves the mechanical properties but also helps in stronger interfacial bonding in polymer composite applications.

Keywords: Alkali treatment; Breaking force; FTIR; Mechanical properties; Pineapple leaf fiber (PALF); SEM; Sodium hydroxide; XRD.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
NaOH treatment of PALF mat.
Fig. 2
Fig. 2
(a) Illustration of the specimen sketch and placement of the PALF mat as per ASTM D5035-11. (b) Side view of the fabric orientation.
Fig. 3
Fig. 3
A digital tensile tester was used for the testing process.
Fig. 4
Fig. 4
X-ray diffraction patterns of (a) all the specimenes, (b) S4, which has the highest crystallinity index, S6 lowest crystallinity index, and S10 (Untreated).
Fig. 5
Fig. 5
The average CI% and its standard deviation.
Fig. 6
Fig. 6
The average CS and its standard deviation.
Fig. 7
Fig. 7
SEM image of (a) Untreated PALF, (b) Low crystallinity specimen S6-9 N-30 M, (c) High crystallinity specimen S4-3 N-60 M.
Fig. 8
Fig. 8
FTIR analysis of the combined graphs of S4, S6, and S10 along with their peaks.
Fig. 9
Fig. 9
Images of PALF mat (a) Before the breaking force test. (b) After the breaking force test as per ASTM D5035.
Fig. 10
Fig. 10
The average breaking force in N and its standard deviation.
See this image and copyright information in PMC

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