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Jute fibres were subjected to a 5% alkali (NaOH) solution treatment for 0, 2, 4, 6 and 8 h at 30°C. An improvement in the crystallinity in the jute fibres increased its modulus 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 the 35% composites with 4 h treated fibres, the flexural strength improved from 199⋅ ⋅1 MPa to 238⋅ ⋅9 MPa by 20%, modulus improved from 11⋅ ⋅89 GPa to 14⋅ ⋅69 GPa by 23% and laminar shear strength increased from 0⋅ ⋅238 MPa to 0⋅ ⋅2834 MPa by 19%. On plotting the different values of slopes obtained from the rates of improvement of the flexural strength and modulus, against the NaOH treatment time, two different failure modes were apparent before and after 4 h of 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 a minimum fibre pull out. This observation was well supported by the SEM investigations of the fracture surfaces.

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Short jute fiber‐reinforced polypropylene (PP) composites were prepared using a high‐speed thermokinetic mixer. A compatibilizer was used to improve the molecular interaction between jute and PP. Both the percent weight fraction of the jute fiber and compatibilizer were varied to study the dynamic mechanical thermal (DMT) properties. Dynamic parameters such as storage flexural modulus (E′), loss flexural modulus (E″), storage shear modulus (G′), loss shear modulus (G″), and loss factor or damping efficiency (tan δ) were determined in a resonant frequency mode. The transition peak nature, amplitude, and temperature of E′, E″, G′, G″, and tan δ of different compositions were shown to indicate possible improvements of molecular interaction in the presence of a compatibilizer. The modulus retention term, a plot of the reduced modulus with the weight fraction of the jute fiber, also indicate its improvement. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 531–539, 1999

Jute fibers were treated with 5% NaOH solution for 2, 4, 6, and 8 h to study the performance of the fibers as a reinforcing material in the composites. Thermal analysis of the fibers was done by the DTG and DSC technique. The moisture desorption was observed at a lower temperature in the case of all the treated fibers, which might be a result of the increased fineness of the fibers, which provides more surface area for moisture evaporation. The decrease in percentage moisture loss for the fibers treated with alkali for 6 and 8 h could be the result of the increased crystallinity of the fibers. The percentage degradation of the hemicellulose decreased considerably in all the treated fibers, conforming to the fact that the hemicellulose content was lowered on alkali treatment. The decomposition temperature for ␣-cellulose was lowered to 348°C from 362.2°C for all the treated fibers, and the residual char formation increased to a significant extent. The enthalpy for the thermal degradation of ␣-cellulose showed a decreasing trend for the fibers treated for 2 and 4 h, which could be caused by the initial loosening of the structure, followed by an increase in the enthalpy value in the case of the 6-and 8-h-alkali-treated fibers resulting from increased crystallinity, as evident from the X-ray diffraction.

Dried and defatted jute fibers were acetylated for different time and temperature in the absence of catalyst and solvent. Extent of acetylation were measured by weight percent gain (WPG). These values were compared with the standard method of acetylation using a cosolvent (pyridine) system. The characterization of acetylated fibers was performed by FTIR, DSC, TGA, and SEM studies. The maximum WPG was 18.0 for an acetic anhydride-pyridine system at 120ЊC for 4 h whereas using only acetic anhydride WPG was 12.3 at the same reaction condition. Thermal stability of acetylated jute was found to be higher than the untreated jute. SEM studies were carried out to investigate the fiber surface morphology. FTIR studies also produced evidence for acetylation.