In this work a study on the feasibility of extracting cellulose from sisal fiber, by means of two different procedures was carried out. These processes included usual chemical procedures such as acid hydrolysis, chlorination, alkaline extraction, and bleaching. The final products were characterized by means of Thermogravimetric Analysis (TGA), Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Scanning Electronic Microscopy (SEM). The extraction procedures that were used led to purified cellulose. Advantages and disadvantages of both procedures were also analyzed. Finally, nanocellulose was produced by the acid hydrolysis of obtained cellulose and characterized by Atomic Force Microscopy (AFM).

Extraction of cellulose and preparation of nanocellulose from sisal fibers

Changes occurring in jute fibers when treated with a 5% concentration of a NaOH solution for 0, 2, 4, 6, and 8 h were characterized by weight loss, linear density, tenacity, modulus, FTIR, and X-ray measurements. A 9.63% weight loss was measured during 2 h of treatment with a drop of hemicellulose content from 22 to 12.90%. The linear density value showed no change until 2 h of treatment followed by a decrease from 33.0 to 14.5 denier by 56% after 6 h of treatment. The tenacity and modulus of the fibers improved by 45 and 79%, respectively, and the percent breaking strain was reduced by 23% after 8 h of treatment. X-ray diffractograms showed increase in crystallinity of the fibers only after 6 h of treatment, while FTIR measurements showed much of the changes occurring by 2 h of treatment with an increased amount of OH groups. By measuring the rate of change of the modulus, tenacity, and percent breaking strain with the time of treatment, a clear transition was apparent at 4 h of treatment with the dissolution of hemicellulose, causing a weight loss and drop in the linear density before and development of crystallinity with an improvement in the properties after the transition time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1013–1020, 2001

Characterization of alkali-treated jute fibers for physical and mechanical properties

Jute fibres were subjected to alkali treatment with 5% NaOH solution for 0, 2, 4, 6 and 8 h at 30°C. The modulus of the jute fibres improved by 12, 68 and 79% after 4, 6 and 8 h of treatment, respectively. The tenacity of the fibres improved by 46% after 6 and 8 h treatment and the % breaking strain was reduced by 23% after 8 h treatment. For 35% composites with 4 h-treated fibres, the flexural strength improved from 199.1 to 238.9 MPa by 20%, modulus improved from 11.89 to 14.69 GPa by 23% and laminar shear strength increased from 0.238 to 0.283 MPa by 19%. On plotting different values of slopes obtained from the rates of improvement of flexural strength and modulus, against NaOH treatment time, two different failure modes were apparent before and after 4 h of NaOH treatment. In the first region between 0 and 4 h, fibre pull out was predominant whereas in the second region between 6 and 8 h, transverse fracture occurred with minimum fibre pull out. This observation was well supported by the SEM investigations of the fracture surfaces.

The mechanical properties of vinylester resin matrix composites reinforced with alkali-treated jute fibres

The mechanical properties of tossa jute fibers were improved by using NaOH treatment process to improve the mechanical properties of composites materials. Shrinkage of fibers during this process has significant effects to the fiber structure, as well as to the mechanical fiber properties, such as tensile strength and modulus. Isometric NaOH-treated jute yarns (20 min at 20°C in 25% NaOH solution) lead to an increase in yarn tensile strength and modulus of ∼ 120% and 150%, respectively. These changes in mechanical properties are affected by modifying the fiber structure, basically via the crystallinity ratio, degree of polymerization, and orientation (Hermans factor). Structure–property relationships, developed for cellulosic man-made fibers, were used with a high correlation factor to describe the behavior of the jute fiber yarns. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 623–629, 1999

Alkali treatment of jute fibers: Relationship between structure and mechanical properties

Publisher Summary This chapter focuses on wood hemicelluloses. The major hemicelluloses of wood, structural details, such as the degree of branching of xylans and glucomannans, the distribution of their various side-chains, and the state of the uronic acid groups in the native xylans remain to be established. The possible presence of D-glucuronic acid and D-xylose residues in arabinogalactans needs confirmation. The physical chemistry of the wood hemicelluloses was largely neglected in the past, despite the many excellent techniques now available for investigating both the solid-state and the solution properties of polymer. The methods available for the structural studies of polysaccharides have been continuously improved over the past ten years. The numerous hemicelluloses occurring in the phloem have only recently attracted attention. In many species, some of them differ considerably from those present in the xylem. Wood hemicelluloses are, next to cellulose, the most abundant chemicals on the earth, a fact that make them a challenging subject for future fundamental and applied research.

Wood Hemicelluloses: Part I

(1948) 4—THE HEMICELLULOSES OF JUTE FIBRE Journal of the Textile Institute Transactions: Vol 39, No 2, pp T44-T58

4—the hemicelluloses of jute fibre

A polyuronide hemicellulose has been isolated from the chlorite holocellulose of jute fiber. It constitutes about 75% of the hemicelluloses of jute and appears to consist of one molecule of monomet...

The Nature of the Hemicelluloses of Jute Fiber: Part I

1—the combination between lignin and polyuronic acid in jute fibre

(1947). 28—THE ACID NATURE OF JUTE FIBRE. Journal of the Textile Institute Transactions: Vol. 38, No. 9, pp. T318-T332.

28—the acid nature of jute fibre

ON account of the fact that some of the xylan in straws and hardwoods remained in the α-cellulose, Hawley and Norman1 considered it to be intimately associated with the α-cellulose. According to Astbury, Preston and Norman2, this association corresponds to the relationship between the components of a solid solution or a mixed crystal. Norman3 regards xylan as an integral part of the cellulosic aggregate, oriented in the same way as true cellulose and taking part in the micelle. This view received support from the fact that xylan-free α-cellulose could not be obtained from many sources4; some celluloses failed to part with their xylan even on boiling with 10 per cent sodium hydroxide5. Chemical combination between xylan and α-cellulose has therefore been suggested.

P. B. Sarkar

Papers

4—the hemicelluloses of jute fibre

The Nature of the Hemicelluloses of Jute Fiber: Part I

1—the combination between lignin and polyuronic acid in jute fibre

28—the acid nature of jute fibre

Association of Xylan with α-Cellulose in Jute