A.K. Mukhopadhyay’s research while affiliated with Indian Jute Industries Research Association and other places

The properties of woven jute/polyethylene fabrics having different constructions have been investigated in order to develop suitable lightweight woven fabrics for the production of sacks. Typical yarn combinations are suggested. Drop tests and other studies have revealed the satisfactory quality of these sacks. Polyethylene tape yarns are used.

A study shows that no significant changes are observed in the fine structure and properties of jute fibres on treatment with 65-98% ethylenediamine (EDA). Only repeated swelling treatments with 98% EDA show a lattice transformation from cellulose I to cellulose II and also an increase in the orientation angle. The effect of EDA on jute differs from that of EDA on cotton, but rather resembles that of caustic soda on jute.

The fracture of dewaxed white jute fibre at various test lengths and at various rates of extension was examined by using a scanning electron microscope. At shorter test lengths (2 cm) the incidence of slippage was predominant. When the test length was increased to 4 cm, particularly at higher rates of extension, sharp catastrophic fractures took place, generally at the weak points. Slippage-type failures mixed with sharp breaks at weak points occurred when the rate of extension was less than 5 mm/min.

The surface features of jute fibers at various stages of growth were studied. In the early stage, incomplete formation of the middle lamella and collapsing of cell walls occur. Fibrillar orientation in the secondary layer of early stage fibers is helically oriented. The angle of the helix gradually decreases with growth, and after 35 days and onwards, fibrils are almost parallel to the fiber axis.

The voltages used by Ray, Sengupta and Das in their study published in this journal in March, 1986 (see abstract 1986/2666) would have caused charging and misleading micrographs of surface structure. This criticism, by A. K. and U. Mukhopadhyay, and the fact that it led to faulty interpretation of damage in processing are all refuted by the original authors who request more details on how micrographs shown in this letter were produced.

The surface features of jute fibers after mild alkali and acid treatments were studied using SEM to reveal the fibrillar arrangement in different layers of the fiber. A few helically wound fibrils were noted.

Results of liquid ammonia treatment on jute yarns and fabrics are presented. Significant increase in elongation-at-break with some increase in tenacity has been observed in the case of jute yarns. As already reported for jute fibers, an optimum period of treatment of about ten minutes has been observed for jute yarns also. Liquid ammonia treatment increases the extension-at-break of jute fabrics also, and this results in significant improvement in tufting performance of the fabric. Pretreatment of jute fabric with liquid ammonia prior to application of Hame-retarding materials gives significant improvement in fire retardant properties.

Changes in the mechanical properties and fine structure of jute fiber on treatment with liquid ammonia have been discussed. It is found that liquid ammonia treatment increases the extensibility of jute fiber without any loss of strength and is thus a desirable swelling agent from the practical point of view, because though caustic soda produces considerable improvement in extensibility of the fiber, it also causes considerable loss of strength due to removal of part of the hemicellulose. The fine structure of the fiber shows a transformation from cellulose I to cellulose III on liquid ammonia treatment followed by removal of ammonia by evaporation in nitrogen atmosphere, whereas the structure reverts to the cellulose I configuration when ammonia is removed by washing in water. X-ray, infrared, density, and moisture-absorption data for the treated fibers are discussed.