Open Access

ARTICLE

Study of the Superficial Modification of Sisal Fibres with Lignin, and Its Use As a Reinforcement Agent in Cementitious Composites

by Plínio B. Mundim, Rondinele A. R. Ferreira, Leila A. C. Motta, Mariana A. Henrique, Daniel Pasquini

1 College of Civil Engineering, Federal University of Uberlândia, Uberlândia, 38400-902, Brazil
2 Chemistry Institute, Federal University of Uberlândia, Uberlândia, 38400-902, Brazil

* Corresponding Authors: Daniel Pasquini. Email: ;

(This article belongs to the Special Issue: 15th Brazilian Polymer Conference (15th CBPol))

Journal of Renewable Materials 2020, 8(8), 891-903. https://doi.org/10.32604/jrm.2020.010655

Received 03 February 2020; Accepted 25 March 2020; Issue published 10 July 2020

Abstract

The objective of this work was to evaluate different superficial treatments of sisal fibres employing lignin, and their use as a reinforcement agent in cementitious composites. The treatments consisted of superficially impregnating sisal fibres (S) with organosolv lignin (LO), organosolv lignin and glutaraldehyde (LOG), Kraft lignin (LK) and Kraft lignin and glutaraldehyde (LKG). The fibre modifications were verified by FTIR-ATR and SEM analyzes, and the presence of lignin on the surface of the fibres was evidenced, confirming the effectiveness of the treatments. The mechanical, thermal (by TGA) and water absorption properties of the fibres before and after the modifications were also investigated. After treatment, the modified fibres presented an expressive reduction of the water absorption and did not show significant changes in the mechanical properties when compared with the natural unmodified sisal fibre (SNAT). It was verified an increase in the thermal stability of the treated fibres which can be attributed to the insertion of lignin on the fibres. To evaluate the performance of the fibres in the cementitious composites, cement plates (CP) were produced with different treated fibres (CP-SLOG, CP-SLO, CP-SLKG, CP-SLK) and fibres without treatment (CP-SNAT). The composites were evaluated concerning to the water absorption, porosity and mechanical properties. The fractured regions were also investigated by SEM. All composites prepared showed similar values of absorption and porosity indexes. From the mechanical properties, the composites prepared with modified fibres showed a significant increase in the modulus of rupture and modulus of elasticity compared with CP-SNAT, while toughness was similar to all samples. From the SEM images, it was observed that the modified fibres immersed in the cementitious plates showed no degradation, indicating that the impregnation of lignin acted as a protective agent of the fibres. Therefore, the treatments of the fibres with lignin led to a significant improvement in the properties of the composites generating a treatment with potential for industrial application.

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